Co-reporter:Hefei Liu, Ziru Huang, Shiyuan Wei, Lingling Zheng, Lixin Xiao and Qihuang Gong
Nanoscale 2016 vol. 8(Issue 12) pp:6209-6221
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5NR05207F
Organic–inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.
Co-reporter:Yusheng Bian and Qihuang Gong
Nanoscale 2015 vol. 7(Issue 10) pp:4415-4422
Publication Date(Web):23 Jan 2015
DOI:10.1039/C4NR06890D
The simultaneous realization of nanoscale field localization and low transmission loss remains one of the major challenges in nanophotonics. Metal nanowire waveguides can fulfill this goal to a certain extent by confining light within subwavelength space, yet their optical performances are still restricted by the tradeoff between confinement and loss, which results in quite limited propagation distances when their mode sizes are reduced down to the nanometer scale. Here we introduce a class of low-loss guiding schemes by integrating silicon-on-insulator (SOI) waveguides with plasmon nanowire structures. The closely spaced silicon and metal configurations allow efficient light squeezing within the nanometer, low-index silica gaps between them, enabling deep-subwavelength light transmission with low modal attenuation. Optimizations of key structural parameters unravel the wide-range existence of the high-performance hybrid nanowire plasmon mode, which demonstrates improved guiding properties compared to the conventional hybrid and nanowire plasmon polaritons. The excitation strategy of the guided mode and the feasibility of the waveguide for compact photonic integration as well as active components are also discussed to lay the foundation for its practical implementation. The remarkable properties of these metallic-nanowire-loaded SOI waveguides potentially lend themselves to the implementation of high performance nanophotonic components, and open up promising opportunities for a variety of intriguing applications on the nanoscale.
Co-reporter:Xiao-Chong Yu;Bei-Bei Li;Pan Wang;Limin Tong;Xue-Feng Jiang;Yan Li;Yun-Feng Xiao
Advanced Materials 2014 Volume 26( Issue 44) pp:7462-7467
Publication Date(Web):
DOI:10.1002/adma.201402085
Co-reporter:Jianjun Chen, Chengwei Sun, Hongyun Li and Qihuang Gong
Nanoscale 2014 vol. 6(Issue 22) pp:13487-13493
Publication Date(Web):21 Aug 2014
DOI:10.1039/C4NR02938K
Surface-plasmon-polariton (SPP) launchers, which can couple the free space light to the SPPs on the metal surface, are among the key elements for the plasmonic devices and nano-photonic systems. Downscaling the SPP launchers below the diffraction limit and directly delivering the SPPs to the desired subwavelength plasmonic waveguides are of importance for high-integration plasmonic circuits. By designing a submicron double-slit structure with different slit widths, an ultra-broadband (>330 nm) unidirectional SPP launcher is realized theoretically and experimentally based on the different phase delays of SPPs propagating along the metal surface and the near-field interfering effect. More importantly, the broadband and unidirectional properties of the SPP launcher are still maintained when the slit length is reduced to a subwavelength scale. This can make the launcher occupy only a very small area of <λ2/10 on the metal surface. Such a robust unidirectional SPP launcher beyond the diffraction limit can be directly coupled to a subwavelength plasmonic waveguide efficiently, leading to an ultra-tight SPP source, especially as a subwavelength localized guided SPP source.
Co-reporter:Hongming Shen, Guowei Lu, Yingbo He, Yuqing Cheng, Haitao Liu and Qihuang Gong
Nanoscale 2014 vol. 6(Issue 13) pp:7512-7518
Publication Date(Web):05 May 2014
DOI:10.1039/C4NR01037J
A three-dimensional corrugated metal tapered probe with surface corrugated gratings at the tip apex is proposed and investigated theoretically, which leads to an obvious emission beaming effect of spontaneous emission from a single emitter near the probe. In contrast with conventional apertureless metal probes, where only the enhancement of an optical near-field is concerned, the corrugated probe is able to manipulate local excitation intensity and far-field emission direction simultaneously. The angular emission from a single dipole source, being placed close to the corrugated probe, falls into a cone with a maximum directivity angle of ±11.6°, which improves the collection efficiency 25-fold. Such a probe simultaneously increases the localized field intensity to about twice as strong as the conventional bare tip. In addition, the radiation pattern is sensitive to the working wavelength and the dipole to tip-apex separation. These findings make a promising route to the development of plasmonic spontaneous emission manipulation based on corrugated tapered antenna—for instance, tip-enhanced spectroscopy, single-molecule sensing, and single-photon source .
Co-reporter:Zhen Chai;Xiaoyong Hu;Yu Zhu;Sibai Sun;Hong Yang
Advanced Optical Materials 2014 Volume 2( Issue 4) pp:320-325
Publication Date(Web):
DOI:10.1002/adom.201300497
Co-reporter:Cuicui Lu;Xiaoyong Hu;Fan Zhang;Hong Yang
Advanced Optical Materials 2014 Volume 2( Issue 12) pp:1141-1148
Publication Date(Web):
DOI:10.1002/adom.201400319
Co-reporter:Zhi Gao;Bo Qu;Haimei Wu;Chao Gao;Hongsheng Yang;Lipei Zhang;Lixin Xiao;Zhijian Chen
Journal of Applied Polymer Science 2014 Volume 131( Issue 10) pp:
Publication Date(Web):
DOI:10.1002/app.40279
ABSTRACT
A donor copolymer Poly{2,6-4,8-bis(2-ethylhexyl)benzo[1,2-b:3,4-b′]dithiophene-5,8-2,3-bis(5-octylthiophen-2-yl)quinoxaline} (PBDTThQx) with benzo[1,2-b:4,5-b′]dithiophene and quinoxaline derivatives was synthesized and characterized with NMR, ultraviolet–visible spectroscopy, thermogravimetric analyses, and cyclic voltammetry. Photovoltaic devices with the configuration indium tin oxide–poly(3,4-ethylenedioxythiophene)–poly(styrene sulfonate)–PBDTThQx–[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM)–LiF–Al were fabricated, in which PBDTThQx performed as the electron donor and PC61BM was the electron acceptor in the active layer. The device presented reasonable photovoltaic properties when the weight ratio of PBDTThQx:PC61BM reached 1:3. The open-circuit voltage, fill factor, and power conversion efficiency were gauged to be 0.75 V, 0.59, and 0.74%, respectively. The experimental data implied that PBDTThQx would be a promising donor candidate in the application of polymer solar cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40279.
Co-reporter:Hongli Liu, Bo Qu, Zhiyuan Cong, Weiping Wang, Chao Gao, Zhongwei An, Zhijian Chen, Lixin Xiao, Qihuang Gong
Synthetic Metals 2014 Volume 192() pp:82-86
Publication Date(Web):June 2014
DOI:10.1016/j.synthmet.2014.03.022
•A fluorine substituted polymer (PBDTFC10DBT) was synthesized.•The PBDTFC10DBT polymer shows a low-lying HOMO energy level as −5.42 eV.•A PCE of 1.19% was achieved for the polymer solar cell blending with PC61BM.An alternating polymer (PBDTFC10DBT) with benzo[1,2-b:4,5-b′]dithiophene (BDT) as electron-rich unit and 4,7-bis(4-decylthiophen-2-yl)-5-fluorine-2,1,3-benzothiadiazole (FC10DBT) as electron-withdrawing unit was synthesized and characterized. PBDTFC10DBT showed similar absorption property with that of the counterpart polymer without fluorine atom (PBDTC10DBT). However, the low-lying highest occupied molecular orbit (HOMO) energy level of PBDTFC10DBT was −5.42 eV, about 0.22 eV deeper than that of PBDTC10DBT. In order to study the photovoltaic properties of the materials, polymer solar cells (PSCs) were fabricated with PBDTFC10DBT as donor blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor. The power conversion efficiency (PCE) of PSC was 1.19% with a high open circuit voltage (Voc) of 0.62 V for an optimized PBDTFC10DBT:PC61BM ratio of 1:4, in comparison with that of PBDTC10DBT-based device (PCE of 0.99% with Voc of 0.53 V). This study indicated that fluorine substituted 4,7-dithiophene-2-yl-2,1,3-benzothia-diazole based copolymers would be promising material for the application in polymer solar cells.
Co-reporter:Yusheng Bian, Qihuang Gong
Optics Communications 2014 Volume 313() pp:27-35
Publication Date(Web):15 February 2014
DOI:10.1016/j.optcom.2013.09.055
The whole set of fundamental all-optical logic gates is realized theoretically using a multi-channel configuration based on one-dimensional (1D) metal–insulator–metal (MIM) structures by leveraging the linear interference between surface plasmon polariton modes. The working principle and conditions for different logic functions are analyzed and demonstrated numerically by means of the finite element method. In contrast to most of the previous studies that require more than one type of configuration to achieve different logic functions, a single geometry with fixed physical dimensions can realize all fundamental functions in our case studies. It is shown that by switching the optical signals to different input channels, the presented device can realize simple logic functions such as OR, AND and XOR. By adding signal in the control channel, more functions including NOT, XNOR, NAND and NOR can be implemented. For these considered logic functions, high intensity contrast ratios between Boolean logic states “1” and “0” can be achieved at the telecom wavelength. The presented all-optical logic device is simple, compact and efficient. Moreover, the proposed scheme can be applied to many other nano-photonic logic devices as well, thereby potentially offering useful guidelines for their designs and further applications in on-chip optical computing and optical interconnection networks.
Co-reporter:Yusheng Bian, Qihuang Gong
Photonics and Nanostructures - Fundamentals and Applications 2014 Volume 12(Issue 3) pp:259-267
Publication Date(Web):June 2014
DOI:10.1016/j.photonics.2014.04.002
•We investigate guiding properties of nanotube-based hybrid waveguides.•Low loss, subwavelength mode size and significant field enhancement can be achieved simultaneously.•Tradeoff between confinement and loss can be further balanced through tuning key physical parameters.We present a comprehensive numerical investigation on the guiding properties of a nanotube based hybrid plasmonic waveguide, which comprises a high-index dielectric nanotube placed above a metallic substrate. It is shown that the incorporation of the nanotube offers additional freedom for tuning the optical performance of the hybrid plasmonic structure when compared to the traditional nanowire based hybrid counterparts, which enables further reduction of the propagation loss and enhanced field confinement inside the gap region, while simultaneously maintaining a subwavelength mode size at appropriate geometries. Systematic geometric parameters mapping considering the size of the nanotube and the dimension of the gap reveals that the tradeoff between the confinement and loss could be further balanced through optimizing key physical parameters. These investigations potentially lay the groundwork for the further applications of nanotube based hybrid structures.
Co-reporter:Qin Hu, Jiang Wu, Chang Jiang, Tanghao Liu, Xinglu Que, Rui Zhu, and Qihuang Gong
ACS Nano 2014 Volume 8(Issue 10) pp:10161
Publication Date(Web):September 26, 2014
DOI:10.1021/nn5029828
The past 5 years have witnessed the rise of highly efficient organometal halide perovskite-based solar cells. In conventional perovskite solar cells, compact n-type metal oxide film is always required as a blocking layer on the transparent conducting oxide (TCO) substrate for efficient electron-selective contact. In this work, an interface engineering approach is demonstrated to avoid the deposition of compact n-type metal oxide blocking film. Alkali salt solution was used to modify the TCO surface to achieve the optimized interface energy level alignment, resulting in efficient electron-selective contact. A remarkable power conversion efficiency of 15.1% was achieved under AM 1.5G 100 mW·cm–2 irradiation without the use of compact n-type metal oxide blocking layers.Keywords: electron-selective contact; interface engineering; perovskite solar cells;
Co-reporter:Linbo Shao;Xue-Feng Jiang;Xiao-Chong Yu;Bei-Bei Li;William R. Clements;Frank Vollmer;Wei Wang;Yun-Feng Xiao
Advanced Materials 2013 Volume 25( Issue 39) pp:5616-5620
Publication Date(Web):
DOI:10.1002/adma201302572
Co-reporter:Lixin Xiao;Xing Xing;Zhijian Chen;Bo Qu;Hsinglin Lan;Junji Kido
Advanced Functional Materials 2013 Volume 23( Issue 10) pp:1323-1330
Publication Date(Web):
DOI:10.1002/adfm.201202194
Abstract
A series of 1,8-naphthyridine derivatives is synthesized and their electron-transporting/injecting (ET/EI) properties are investigated via a multilayered electrophosphorescent organic light-emitting device (OLED) using fac-tris(2-phenylpyridine)iridium [Ir(ppy)3] as a green phosphorescent emitter doped into a 4,4′-N,N′-dicarbazolebiphenyl (CBP) host with 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (a-NPD) as the hole-transporting layer, and poly(arylene ether sulfone) containing tetraphenylbenzidine (TPDPES) doped with tris(4-bromophenyl)ammonium hexachloroantimonate (TBPAH) as the hole-injecting layer. The turn-on voltage of the device is 2.5 V using 2,7-bis[3-(2-phenyl)-1,8-naphthyridinyl]-9,9-dimethylfluorene (DNPF), lower than that of 3.0 V for the device using a conventional ET material. The maximum current efficiency (CE) and power efficiency (PE) of the DNPF device are much higher than those of a conventional device. With the aid of a hole-blocking (HB) and exciton-blocking layer of bathocuproine (BCP), 13.2–13.7% of the maximum external quantum efficiency (EQE) and a maximum PE of 50.2–54.5 lm W−1 are obtained using the naphthyridine derivatives; these values are comparable with or even higher than the 13.6% for conventional ET material. The naphthyridine derivatives show high thermal stabilities, glass-transition temperatures much higher than that of aluminum(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (BAlq), and decomposition temperatures of 510–518 °C, comparable to or even higher than those of Alq3.
Co-reporter:Guowei Lu, Jie Liu, Tianyue Zhang, Hongming Shen, Pascal Perriat, Matteo Martini, Olivier Tillement, Ying Gu, Yingbo He, Yuwei Wang and Qihuang Gong
Nanoscale 2013 vol. 5(Issue 14) pp:6545-6551
Publication Date(Web):15 May 2013
DOI:10.1039/C3NR01306E
We propose and justify by the finite-difference time-domain method an efficient strategy to enhance the spontaneous emission of a fluorophore with a multi-resonance plasmonic antenna. The custom-designed asymmetrical antenna consists of two plasmonic nanoparticles with different sizes and is able to couple efficiently to free space light through multiple localized surface plasmon resonances. This design simultaneously permits a large near-field excitation near the antenna as well as a high quantum efficiency, which results in an unusual and significant enhancement of the fluorescence of a single emitter. Such an asymmetrical antenna presents intrinsic advantages over single particle or dimer based antennas made using two identical nanostructures. This promising concept can be exploited in the large domain of light–matter interaction processes involving multiple frequencies.
Co-reporter:Yu Zhu;Xiaoyong Hu;Yongyang Huang;Hong Yang
Advanced Optical Materials 2013 Volume 1( Issue 1) pp:61-67
Publication Date(Web):
DOI:10.1002/adom.201200025
Co-reporter:Tianyue Zhang;Hongming Shen;Guowei Lu;Jie Liu;Yingbo He;Yuwei Wang
Advanced Optical Materials 2013 Volume 1( Issue 4) pp:335-342
Publication Date(Web):
DOI:10.1002/adom.201200041
Photoluminescence of single gold bipyramid due to the radiative decay of the longitudinal surface plasmon is used to determine its 3D orientation using a direct emission pattern imaging technique. The photoluminescence (PL) intensity from individual gold bipyramids is recorded at the objective's back focal plane, which directly maps the angular emission distribution. By correlating the PL spectra, dark-field scattering, emission pattern, and atomic force microscopy data, the spatial orientation and the radiation characteristics of an individual nanoantenna can be unambiguously determined. The PL emission pattern imaging can be used as a stand-alone technique for the fast and facile determination of nanoantenna orientations. The experimental data also agree well with a simple analytical model based on a far-field angular distribution of an isolated dipole emitter on the interface. In situ measurements are also performed on the PL pattern of a single gold bipyramid during optical heating to monitor the photothermal reshaping of the nanoantenna. The results show that the PL emission pattern imaging method is highly sensitive to changes of the geometry and orientation of the nanoparticle. The PL direct imaging technique offers great advantages, including a facile full-3D angle-resolved capability, free of photobleaching and photoblinking. Additionally, the results reveal that the gold bipyramids can generate efficient PL emission, and the unique features of gold bipyramids would be outstanding candidates for orientation sensing. These findings have great potential for characterizing optical nanoantennas, for optical imaging and sensing in materials science and biological applications.
Co-reporter:Cuicui Lu;Xiaoyong Hu;Hong Yang
Advanced Optical Materials 2013 Volume 1( Issue 11) pp:792-797
Publication Date(Web):
DOI:10.1002/adom.201300174
Co-reporter:Zhi Gao, Bo Qu, Haimei Wu, Hongsheng Yang, Chao Gao, Lipei Zhang, Lixin Xiao, Zhijian Chen, Wei Wei, Qihuang Gong
Synthetic Metals 2013 Volume 172() pp:69-75
Publication Date(Web):15 May 2013
DOI:10.1016/j.synthmet.2013.04.006
•A fluorine-functionalized polymer (PBDTFQx) was synthesized and characterized.•Photovoltaic devices based on bulk heterojunction of PBDTFQx and PC61BM were studied.•The acceptable PSCs exhibited FF and PCE of 0.54% and 1.02%, respectively.A new alternating polymer (PBDTFQx) with alkoxy-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) as donor and fluorine-functionalized quinoxaline derivative (FQx) as acceptor, was synthesized and characterized using NMR, UV–vis spectroscopy, thermogravimetric analyses (TGA), and cyclic voltammetry. Photovoltaic devices with the configuration of ITO/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)/PBDTFQx: [6,6]-phenyl C61-butyric acid methyl ester (PC61BM)/LiF/Al were fabricated, in which PBDTFQx performed as the electron donor and PC61BM as the electron acceptor. When the optimized weight ratio of PBDTFQx:PC61BM reached 1:2, the photovoltaic device exhibited acceptable performance with the open-circuit voltage (Voc), the short-circuit current density (Jsc), the fill factor (FF), and the power conversion efficiency (PCE) of 0.77 V, 2.46 mA/cm2, 0.54% and 1.02%, respectively. The experimental data implied that PBDTFQx would be a promising donor candidate in the application of polymer solar cells.
Co-reporter:Yi-Wen Hu, Bei-Bei Li, Yi-Xiang Liu, Yun-Feng Xiao, Qihuang Gong
Optics Communications 2013 Volume 291() pp:380-385
Publication Date(Web):15 March 2013
DOI:10.1016/j.optcom.2012.11.024
We theoretically study hybrid photonic–plasmonic modes in a composite structure in which a silicon microdisk is vertically coupled to a metal microdisk. Benefitting from the low-loss property of whispering gallery modes and the strong field localization of plasmonic modes, the hybrid modes hold potential advantages over conventional photonic or plasmonic devices, in particular toward sensing and nanoparticle trapping. In the refractometer application, a high figure of merit exceeding 200 can be obtained in 1550 nm wavelength band. In the nanoparticle trapping, the composite structure enables a significant power enhancement in the hybrid mode, and the gradient force reaches as high as 48 pN/W for a single polystyrene nanoparticle with a radius of 5 nm. Since the enhanced gradient force pulls the nanoparticles into the area with the strongest electromagnetic field, this composite device is beneficial to nanoparticle detection with low noise and fast response.
Co-reporter:Yusheng Bian, Qihuang Gong
Optics Communications 2013 Volume 308() pp:30-35
Publication Date(Web):1 November 2013
DOI:10.1016/j.optcom.2013.06.034
The guiding properties of a one-dimensional hybrid metal–insulator–metal (MIM) waveguiding structure that incorporates an additional high-index dielectric layer sandwiched between two low-index-dielectric–metallic walls are investigated numerically at the telecom wavelength. Compared with the conventional MIM waveguide, the hybrid MIM structure can achieve both lower propagation loss and enhanced optical confinement under careful design. 2D modal analysis combined with investigation on its transmission properties reveals that the crosstalk between adjacent waveguides can be significantly reduced by replacing the traditional MIM waveguides with their hybrid MIM counterparts. These investigations could offer useful guidelines for the design and optimization of hybrid plasmonic waveguides and components.
Co-reporter:Bo Qu, Di Tian, Zhiyuan Cong, Weiping Wang, Zhongwei An, Chao Gao, Zhi Gao, Hongsheng Yang, Lipei Zhang, Lixin Xiao, Zhijian Chen, and Qihuang Gong
The Journal of Physical Chemistry C 2013 Volume 117(Issue 7) pp:3272-3278
Publication Date(Web):January 29, 2013
DOI:10.1021/jp311059d
Highly efficient PBDTTPD-based photovoltaic devices with the configuration of ITO/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/PBDTTPD: methanofullerene (6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) (weight ratio being from 1:1 to 1:4)/LiF (5 Å)/Al (100 nm), were realized with ortho-dichlorobenzene (DCB) solvent annealing treatment. It was revealed that the best photovoltaic device was obtained when the blend ratio of PBDTTPD:PC61BM was modulated to be 1:2 and processed with DCB solvent annealing for 12 h. The short-circuit current density (Jsc) and power conversion efficiency (PCE) values were measured to be 10.52 mA/cm2 and 4.99% respectively, which were both higher than the counterparts treated with chlorobenzene (CB) solvent annealing or the thermal annealing. Atomic force microscopy measurements of the active layer after solvent annealing treatment were also carried out. The phase separation length scale of the PBDTTPD:PC61BM(1:2) layer was comparable to the exciton diffusion length when the active layer was treated under DCB solvent annealing, which facilitated effective exciton dissociation and carrier diffusion in the active layer. Therefore, highly efficient PBDTTPD-based photovoltaic devices could be achieved with DCB solvent annealing, which indicated that solvent annealing with proper solvent might be an easily processed, low-cost, and room-temperature alternative to thermal annealing for polymer solar cells.
Co-reporter:Ying Gu, Luojia Wang, Pan Ren, Junxiang Zhang, Tiancai Zhang, Olivier J. F. Martin, and Qihuang Gong
Nano Letters 2012 Volume 12(Issue 5) pp:2488-2493
Publication Date(Web):April 18, 2012
DOI:10.1021/nl300655n
The mechanism of using the anisotropic Purcell factor to control the spontaneous emission linewidths in a four-level atom is theoretically demonstrated; if the polarization angle bisector of the two dipole moments lies along the axis of large/small Purcell factor, destructive/constructive interference narrows/widens the fluorescence center spectral lines. Large anisotropy of the Purcell factor, confined in the subwavelength optical mode volume, leads to rapid spectral line narrowing of atom approaching a metallic nanowire, nanoscale line width pulsing following periodically varying decay rates near a periodic metallic nanostructure, and dramatic modification on the spontaneous emission spectrum near a custom-designed resonant plasmon nanostructure. The combined system opens a good perspective for applications in ultracompact active quantum devices.
Co-reporter:Jianjun Chen, Zhi Li, Song Yue, Jinghua Xiao, and Qihuang Gong
Nano Letters 2012 Volume 12(Issue 5) pp:2494-2498
Publication Date(Web):April 3, 2012
DOI:10.1021/nl300659v
By utilizing a dielectric-film-coated asymmetric T-shape single slit, comprising two grooves of slightly detuned widths immediately contacting with a single nanoslit, the plasmon-induced transparency was experimentally demonstrated. Because of the symmetry breaking in the unit-cell structure, the scattered lights from the two grooves with slightly detuned widths interfere destructively, leading to the plasmon-induced transparency. As a result, a response spectrum with nearly the same interference contrast but a much narrower bandwidth emerges in the unit-cell structure with the footprint of only about 0.9 μm2, compared with that in the symmetric T-shape single slit. These pronounced features in the structure, such as the increased quality factor, ultracompact size, easy fabrication, and experimental observation, have significant applications in ultracompact plasmonic devices.
Co-reporter:Yulan Fu, Xiaoyong Hu, Cuicui Lu, Song Yue, Hong Yang, and Qihuang Gong
Nano Letters 2012 Volume 12(Issue 11) pp:5784-5790
Publication Date(Web):November 1, 2012
DOI:10.1021/nl303095s
We report realizations of nanoscale integrated all-optical XNOR, XOR, NOT, and OR logic gates using plasmonic slot waveguides based on linear interference between surface plasmon polariton modes. The miniature device size with lateral dimensions smaller than 5 μm, precisely controlled optical phase difference, and quasi-monochromatic surface plasmon polariton modes excited by a continuous wave 830 nm laser beam ensure a high intensity contrast ratio of 24 dB between the output logic states “1” and “0”. Compared with previous reported results, the intensity contrast ratio is enhanced 4-fold, whereas the lateral dimension is reduced 4-fold. These compact logic devices are stable, robust, free from environmental impact, and much suitable for practical on-chip applications. These also provide a means to construct all-optical logic devices and nanophotonic processors.
Co-reporter:Xing Xing, Lixin Xiao, Lingling Zheng, Shuangyuan Hu, Zhijian Chen, Bo Qu and Qihuang Gong
Journal of Materials Chemistry A 2012 vol. 22(Issue 30) pp:15136-15140
Publication Date(Web):07 Jun 2012
DOI:10.1039/C2JM32512H
A spirobifluorene derivative containing phenanthrene moiety, 2,7-di(phenanthren-9-yl)-9,9′-spirobifluorene (DPSF), has been synthesized. It shows absorption peaks at 254 nm, 310 nm, and 327 nm and a fluorescence peak at 383 nm in CHCl3 that shifts to 398 nm in the film state. The quantum yield is 0.79 calibrated with a standard of coumarin 102 (0.93). A pure blue emission at Commission Internationale de l′Éclairage (CIE) (0.15, 0.08), has been achieved using DPSF as the emitter, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) as the hole injecting layer, 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino] biphenyl (NPB) as the hole transporting layer, and 1,3,5-tris(N-phenylbenzimidazol-2-yl)-benzene (TPBI) mixing with 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (2:1) as the electron transporting material. The maximum current efficiency (CE) and power efficiency (PE) of the DPSF device are 3.24 cd A−1 and 2.54 lm W−1, corresponding to 5.41% of maximum external quantum efficiency (EQE). The spirobifluorene derivative show high thermal stabilities, 178 °C for the glass transition temperature (Tg) and 503 °C for the decomposition temperature (Td). The synthesized spirobifluorene derivative shows potential application as a highly efficient pure blue emitter for organic light emitting devices (OLED).
Co-reporter:Guowei Lu, Jie Liu, Tianyue Zhang, Wenqiang Li, Lei Hou, Chunxiong Luo, Franck Lei, Michel Manfait and Qihuang Gong
Nanoscale 2012 vol. 4(Issue 11) pp:3359-3364
Publication Date(Web):30 Mar 2012
DOI:10.1039/C2NR12137A
We proposed the estimation of the plasmonic near-field volume in the vicinity of a single gold nanoparticle, and observed experimentally the near-field variation due to a change in the polarization of the illuminating light. Under total-internal-reflection illumination, the plasmonic near-field volume is varied by tuning the polarization of the excitation light. The variation in the optical near-field around a single gold nanoparticle was simulated theoretically with a finite-difference time domain method, and was characterized experimentally employing a fluorescence correlation spectroscopy technique. The experimental results are in agreement quantitatively with the theoretical analysis. These results are highly relevant to important efforts to clarify the interaction between the emitter and the plasmonic antenna, and should be helpful in developing a plasmonic-enhanced total-internal-reflection fluorescence imaging microscope.
Co-reporter:Xing Xing, Lipei Zhang, Rui Liu, Suyue Li, Bo Qu, Zhijian Chen, Wenfang Sun, Lixin Xiao, and Qihuang Gong
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 6) pp:2877
Publication Date(Web):June 7, 2012
DOI:10.1021/am300685b
Highly efficient deep-blue organic light-emitting devices (OLEDs) have been fabricated using 2,7-di(2,2′:6′,2″-terpyridin-4-yl)-9,9-dioctyl-9H-fluorene (DTPF) as the emitter, which has a wide energy gap, high emission quantum yield (Φf = 0.88), and high electron transporting property to improve the charge balance. A high efficiency of 2.55 cd/A and 2.67 lm/W are obtained in OLED. The device also exhibits a low turn-on voltage of 3.0 V and Commission Internationale de l′Éclairage (CIE) coordinates of (0.16, 0.09).Keywords: charge balance; deep-blue; electron transport; emitter; organic light-emitting device;
Co-reporter:Xing Xing, Taiju Tsuboi, Yosuke Nakai, Fei Wang, Boyuan Qi, Zhijian Chen, Bo Qu, Lixin Xiao, Qihuang Gong
Organic Electronics 2012 Volume 13(Issue 1) pp:195-198
Publication Date(Web):January 2012
DOI:10.1016/j.orgel.2011.10.019
Co-reporter:Bo Qu, Limin Feng, Hongsheng Yang, Zhi Gao, Chao Gao, Zhijian Chen, Lixin Xiao, Qihuang Gong
Synthetic Metals 2012 Volume 162(17–18) pp:1587-1593
Publication Date(Web):October 2012
DOI:10.1016/j.synthmet.2012.06.021
A novel soluble terpolymer (P8FO-Th-BT) containing 9,9-dioctylfluorene, thiophene, and 2,1,3-benzothiadiazole units were synthesized by Still coupling reaction. The single layer and multi-layer organic light emitting diodes (OLEDs) based on P8FO-Th-BT was fabricated. A deep red-emission device with the configuration of ITO/poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS)/P8FO-Th-BT:N,N′-di(3-methylphenyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4-diamine (TPD) (weight ratio being 1:1)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, 15 nm)/tris(8-hydroxyquinoline) aluminum (Alq3, 15 nm)/LiF(5 Å)/Al(150 nm) was obtained, and the maximum luminance was measured to be 226 cd/m2 at the bias voltage of 10 V. The electroluminescent peak located at 708 nm, and the spectrum covered both the red and infrared regions. Moreover, the Commission International De L’Eclairage (CIE) chromaticity coordinates of the device were inalterable when the bias voltage varied, which was beneficial to the application on display.Highlights► A novel soluble terpolymer (P8FO-Th-BT) was synthesized by Still coupling reaction. ► A deep red-emission device based on P8FO-Th-BT was investigated in detail. ► The electroluminescent peak was 708 nm and the CIE coordinates were inalterable.
Co-reporter:Bo Qu, Hongsheng Yang, Di Tian, Hongli Liu, Zhiyuan Cong, Chao Gao, Zhijian Chen, Lixin Xiao, Zhi Gao, Wei Wei, Qihuang Gong
Synthetic Metals 2012 Volume 162(Issue 23) pp:2020-2026
Publication Date(Web):December 2012
DOI:10.1016/j.synthmet.2012.09.009
Two D–A conjugated polymers (named PBDTC6DBT and PBDTC10DBT) with benzo[1,2-b:3,4-b′]dithiophene (BDT) as donor and 4,7-dithiophen-2,1,3-benzothiadiazole (DBT) as acceptor, were designed and synthesized. PBDTC6DBT and PBDTC10DBT have hexyl and decyl as side chains in the DBT units, respectively. The polymers were characterized by spectroscopic (NMR and UV–vis) methods, GPC, DSC and cyclic voltammetry. In order to study the photovoltaic properties of the two conjugated polymers, photovoltaic devices with the configuration of ITO/poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS)/polymer:[6,6]-phenyl C61-butyric acid methyl ester (PC61BM)/LiF/Al, were fabricated, in which PBDTC6DBT or PBDTC10DBT acted as electron donor in active layers. According to the experimental data, when the blend ratio of PBDTC6DBT and PC61BM reached 1:2, the best photovoltaic properties among the PBDTC6DBT-based devices were obtained, and the open-circuit voltage, the short-circuit current density and the power conversion efficiency were measured to be 0.63 V, 6.18 mA/cm2 and 1.86%, respectively. As to PBDTC10DBT-based devices, the maximum of power conversion efficiency reached 0.99% with the blend ratio of PBDTC10DBT and PC61BM being 1:2. PBDTC10DBT and PBDTC6DBT were both promising donor candidates in the application of polymer solar cells.Highlights► PBDTC6DBT and PBDTC10DBT with benzo[1,2-b:3,4-b′]dithiophene and 4,7-dithiophen-2,1,3-benzothiadiazole segments were synthesized. ► Photovoltaic devices based on PBDTC6DBT and PBDTC10DBT were investigated. ► The highest power conversion efficiency of the OPVs was measured to be 1.86%.
Co-reporter:Saisai Chu, Shufeng Wang, Qihuang Gong
Chemical Physics Letters 2012 Volume 523() pp:104-106
Publication Date(Web):27 January 2012
DOI:10.1016/j.cplett.2011.12.024
The ultrafast third-order nonlinear optical properties of graphene in both suspension and film status are studied using femtosecond time resolved optical Kerr gate technique at 800 nm. The third-order nonlinear optical susceptibility is 4.2 × 10−14 esu for solution of 0.010 mg/ml. The corresponding second-order hyperpolarizability is 3.4 × 10−32 esu per carbon atom in graphene, which is the largest among the carbon family. The graphene embed in the polymer matrix of polyvinyl alcohol film (OD = 0.43) exhibits strong ultrafast nonlinear optical response of 3.3 × 10−12 esu and shows its potential application in nonlinear optics.Graphical abstractHighlights► Ultrafast third-order nonlinear optics of graphene was investigated by OKE. ► γc Of graphene was determined to be 3.4 × 10−32 esu per carbon atom. ► The χ(3) of graphene/PVA film (OD = 0.52) was measured 3.1 × 10−12 esu.
Co-reporter:Tianyue Zhang, Guowei Lu, Wenqiang Li, Jie Liu, Lei Hou, Pascal Perriat, Matteo Martini, Olivier Tillement, and Qihuang Gong
The Journal of Physical Chemistry C 2012 Volume 116(Issue 15) pp:8804-8812
Publication Date(Web):March 21, 2012
DOI:10.1021/jp2125944
Nanoshell and Matryoshka-nanoshell constructs are rationally optimized utilizing the finite-difference time-domain method to design probes with enhanced fluorescence. Through the systematical investigation of interactions between the spontaneous emission of a single emitter and a metal-based nanostructure, the plasmonic-enhanced fluorescence is found maximal for certain morphologies that balance two competitive factors: field enhancement and quantum efficiency. For instance, key parameters such as the emitter’s position, its orientation, and the spectral overlaps between molecular bands and plasmon resonance are investigated to fully understand the complete behavior of the system. In the case of metal nanoshells, it is shown that the molecular fluorescence is differently enhanced inside or outside the shell. In that of Matryoshka-nanoshells that consist of concentric gold core and shell, the construct appears as an exceptionally promising probe especially when the fluorophore lies within the gap layer. Indeed, the strong coupling between the adjacent core and shell allows electromagnetic excitation to be squeezed within the gap, so resulting in giant fluorescence and photostability. Such a construct opens a way for still increasing the sensitivity of fluorescence detection, which is promising for almost all biological imaging applications.
Co-reporter:Haimei Wu, Bo Qu, Zhiyuan Cong, Hongli Liu, Di Tian, Bowen Gao, Zhongwei An, Chao Gao, Lixin Xiao, Zhijian Chen, Huanhuan Liu, Qihuang Gong, Wei Wei
Reactive and Functional Polymers 2012 72(11) pp: 897-903
Publication Date(Web):November 2012
DOI:10.1016/j.reactfunctpolym.2012.07.006
Co-reporter:Guowei Lu, Wenqiang Li, Tianyue Zhang, Song Yue, Jie Liu, Lei Hou, Zhi Li, and Qihuang Gong
ACS Nano 2012 Volume 6(Issue 2) pp:1438
Publication Date(Web):January 16, 2012
DOI:10.1021/nn2042412
We report experimental behaviors of polarization-dependent, plasmonic-enhanced molecular fluorescence within isolated bowtie nano-apertures (BNAs) milled in aluminum films. BNAs provide efficient control of the fluorescent count rate per molecule and the decay lifetime of the molecules and provide an effective detection volume at the nanometer scale by tuning either the excitation light polarization or the BNA size. Interestingly, large BNAs (>300 nm) present high plasmonic-enhanced fluorescence efficiency and can simultaneously confine the detection volume below the subdiffraction limit. Numerical simulations were performed that agreed qualitatively with the experimental results. The BNAs have potential applications, especially for single-molecule biological analysis.Keywords: bowtie nano-aperture; fluorescence; lifetime; plasmonic; scattering
Co-reporter:Guowei Lu, Lei Hou, Tianyue Zhang, Jie Liu, Hongming Shen, Chunxiong Luo, and Qihuang Gong
The Journal of Physical Chemistry C 2012 Volume 116(Issue 48) pp:25509-25516
Publication Date(Web):November 7, 2012
DOI:10.1021/jp309450b
Label-free plasmonic sensors based on localized surface plasmon resonances of nanostructured noble metal materials usually transduce optical refractive index changes occurring in the vicinity of the nanostructures by optical scattering or by extinction. We demonstrate in experiments that the photoluminescence of plasmonic nanoparticles can also be employed to detect biological molecule binding events efficiently. Photoluminescence probably due to plasmon emission of a single gold nanorod presents a similar resonance peak and resembles the response to a refractive index change observed by scattering. The well-known biotin–streptavidin binding assay was detected successfully using the photoluminescence of an individual isolated nanorod. The localized surface plasmon resonances’ responses by scattering in situ with the same nanorod and control experiments were also performed to verify the sensing process. The results evidence that a nanoscale plasmonic sensor can also be archived effectively through the photoluminescence of a single plasmonic nanostructure. Furthermore, key parameters to optimize the photoluminescence based label-free plasmonic sensing are discussed in detail. The photoluminescence provides an alternative way for label-free plasmonic sensing. And it is believed that further exploration of this concept could lead to a whole new class of efficient plasmonic sensors with diverse and novel functionalities.
Co-reporter:Chao Gao, Bo Qu, Dong Chen, Zhiyuan Cong, Jianqun Liu, Jian Chen, Zhongwei An, Zhijian Chen, Lixin Xiao, Wei Wei, Qihuang Gong
Reactive and Functional Polymers 2012 72(2) pp: 122-126
Publication Date(Web):February 2012
DOI:10.1016/j.reactfunctpolym.2011.11.004
Co-reporter:Yu Zhu;Xiaoyong Hu;Cuicui Lu;Yongyang Huang
Plasmonics 2012 Volume 7( Issue 4) pp:589-594
Publication Date(Web):2012 December
DOI:10.1007/s11468-012-9346-4
An all-optical tunable nanoscale wavelength-division multiplexing device is realized theoretically based on a plasmonic microstructure, which is composed of a silver film coated with a monolayer colloidal crystal made of cholesteryl iodide-doped polystyrene. The physical mechanism is attributed to the variation of surface plasmon polariton modes and guided modes caused by pump-laser-induced refractive index change of cholesteryl iodide. An up to 90-nm shift in the resonant wavelength of optical channels can be reached under excitation of a 500 mJ/cm2 pump laser. The number of optical channels can be tuned by adjusting the structure parameters of the monolayer colloidal crystal. This may open a new way for the study of integrated photonic devices.
Co-reporter:Jianjun Chen, Zhi Li, Song Yue, and Qihuang Gong
Nano Letters 2011 Volume 11(Issue 7) pp:2933-2937
Publication Date(Web):June 13, 2011
DOI:10.1021/nl201401w
By engaging a compact asymmetric single slit coated with a photorefractive polymer, surface-plasmon-polariton (SPP) generation was efficiently controlled by a pump beam. In the structure, the nonlinear light–matter interaction is enhanced because of the cavity effect, which increases the sensitivity of SPPs to the surrounding dielectric. By variation of the real part of the refractive index together with an interferometric configuration, high on/off switching ratios are achieved. Moreover, the SPP generation and modulation processes are integrated in the same asymmetric single slit, which makes the device ultracompact. Experimentally, a high on/off switching ratio of >20 dB and phase variation of >π were observed with the device lateral dimension of only about 2 μm.
Co-reporter:Xiaoyong Hu;Zhiqiang Li;Jiaxiang Zhang;Hong Yang;Xinping Zhang
Advanced Functional Materials 2011 Volume 21( Issue 10) pp:1803-1809
Publication Date(Web):
DOI:10.1002/adfm.201002445
Abstract
A novel nanoscale integrated all-optical diode is reported, realized by combining the strong plasmonic responses of gold nanoparticles with the all-optical tunable properties of polymeric photonic crystal microcavities. Non-reciprocal transmission properties are achieved based on the effect of surface-plasmon resonance enhancing the optical non-linearity and dynamic coupling of asymmetrical microcavity modes. An ultralow-threshold photon intensity of 2.1 MW cm−2 and an ultrahigh transmission contrast over 104 are realized simultaneously. Compared with previously reported all-optical diodes, the operating power is reduced by five orders of magnitude, while the transmission contrast is enlarged by three orders of magnitude.
Co-reporter:Lixin Xiao, Boyuan Qi, Xing Xing, Lingling Zheng, Sheng Kong, Zhijian Chen, Bo Qu, Lipei Zhang, Ziwu Ji and Qihuang Gong
Journal of Materials Chemistry A 2011 vol. 21(Issue 47) pp:19058-19062
Publication Date(Web):28 Oct 2011
DOI:10.1039/C1JM13488D
A high triplet energy (ET = 3.2 eV) electron transporting/hole blocking (ET/HB) material, 1,2,4,5-tetra(3-pyrid-3-yl-phenyl)benzene (TemPPB) with a super twisted structure and high thermal stability has been synthesized. An external quantum efficiency (EQE) of 19.6% was achieved by using TemPPB as the ET/HB material in a blue electrophosphorescent device, much higher than the EQE of 12.5% for the device using the conventional ET material, 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ). In addition, the weak ET property of TemPPB resulting from its super twisted structure can be enhanced via n-type doping with LiF. An EQE of 24.5% was achieved by combining n-type doping and a double-emission layer. This shows an alternative way to design ET/HB materials with high ET and improved thermal stability for blue electrophosphorescent devices.
Co-reporter:Qing Ding, Fushun Liang, Kang Meng, Saisai Chu, Shufeng Wang, Qihuang Gong
Chemical Physics Letters 2011 Volume 504(1–3) pp:52-55
Publication Date(Web):28 February 2011
DOI:10.1016/j.cplett.2011.01.048
Abstract
Ultrafast dynamics of newly synthesized low band gap polymers polyfluorene–thiophene–benzothiadiazole are studied. Additional carbazole groups are added to the side chain to modify its morphological and electronic characters. In solution, ultrafast interband excitation energy transfer is found to be faster in polymer without carbazole side group. In film form, fast quenching happens for exciton–exciton annihilation and charge recombination. The existence of carbazole group dramatically affects the excitation behavior of the film. The polaron-pair recombination was resolved dominant with carbazole group present in side chain.
Co-reporter:Chao Gao, Bo Qu, Zhongliang Jiang, Di Tian, Hongli Liu, Zhijian Chen, Lixin Xiao, Qihuang Gong
Synthetic Metals 2011 Volume 161(9–10) pp:864-868
Publication Date(Web):May 2011
DOI:10.1016/j.synthmet.2011.02.014
A new soluble polythiophene copolymer with phenylene–vinylene conjugated side chain (PEHOPVTh-Th) was synthesized. Polymer photovoltaic solar cells using PEHOPVTh-Th as donor and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor was demonstrated. The absorption spectrum of the PEHOPVTh-Th showed strong absorption in the visible region and a 55 nm red-shift in comparison with that of its homopolymer (PEHOPVTh). By adjusting the ratio of PEHOPVTh-Th to PC61BM, the polymer solar cells based on PEHOPVTh-Th showed a power conversion efficiency of 0.37% under 100 mW/cm2 AM 1.5G simulated sunlight when the weight ratio of the polymer to PC61BM equals to 1:3.
Co-reporter:Qingyan Wang, Guowei Lu, Lei Hou, Tianyue Zhang, Chunxiong Luo, Hong Yang, Grégory Barbillon, Franck H. Lei, Christophe A. Marquette, Pascal Perriat, Olivier Tillement, Stéphane Roux, Qi Ouyang, Qihuang Gong
Chemical Physics Letters 2011 Volume 503(4–6) pp:256-261
Publication Date(Web):17 February 2011
DOI:10.1016/j.cplett.2011.01.005
Abstract
Dynamic behavior of fluorescent molecules near an individual gold nanoparticle is investigated experimentally by fluorescence correlation spectroscopy method. The gold particle that acts as an optical nano-antenna presents significant near-field volume reduction. The single molecule diffusion behavior is clearly observed within a reduced near-field volume due to a highly localized field enhancement. The near-field volume and fluorescence enhancement are polarization and concentration dependent and strongly depend on the properties of the gold nanoparticle. A simple approximated model is developed to fit the FCS autocorrelation curves. In principle, the single molecule analysis within the near-field volume of nanostructures could be applied to the analysis of biological membranes and intracellular processes.
Co-reporter:Qing Ding, Kang Meng, Hong Yang, Shufeng Wang, Qihuang Gong
Optics Communications 2011 Volume 284(Issue 12) pp:3110-3113
Publication Date(Web):1 June 2011
DOI:10.1016/j.optcom.2011.02.059
We setup an ultrafast noncollinear optical parametric amplification system for fluorescence spectral dynamics study. The simultaneous broadband amplifying ability makes it suitable as an ultrafast spectrometer with femtosecond time-resolution. By real-time fluctuation correction, femtosecond fluorescence spectra are obtained efficiently by a single scan. With this technique, the solvation dynamics of DCM dye in four solvents are measured to demonstrate the performance of the system. We show that this ultrafast time-resolved spectrometer is very useful and efficient in studying ultrafast spectral dynamics.Research highlights► Femtosecond fluorescent spectrometer based on non-collinear parametric amplification. ► Full fluorescence spectral decay at femtosecond time resolution is achieved by single temporal scan. ► Spectral dynamics can be observed and studied directly in this spectrometer system.
Co-reporter:Saisai Chu, Shufeng Wang, Yongkai Deng, Qihuang Gong
Optics Communications 2011 Volume 284(16–17) pp:4070-4072
Publication Date(Web):1 August 2011
DOI:10.1016/j.optcom.2011.04.069
Two-photon fluorescence (TPF) process is an important research subject and can be optimized by pulse shaping techniques. In addition to temporal femtosecond pulse shaping by spectral phase modulation, we take into account of spatial configuration in the shaping process. The TPF of Coumarin 500 increases 40% with this additional modulation step. This spatial modulation results in not only transverse spatial profile variation but also effect of temporal redistribution at focus. We show that this spatial modulation is an important dimension for pulse shaping and optimization for TPF.Research highlights► Two photon fluorescence of Coumarin 500 was optimized by combined temporal–spatial pulse shaping using a 2D phase modulator. ► When the spatial phase modulation was applied, the intensity of two photon fluorescence of Coumarin 500 can be further optimized by 40% in addition to temporal only pulses shaping. ► The spatial modulation results in not only spatial profile variation but also effect of temporal redistribution at focus.
Co-reporter:Guowei Lu, Tianyue Zhang, Wenqiang Li, Lei Hou, Jie Liu, and Qihuang Gong
The Journal of Physical Chemistry C 2011 Volume 115(Issue 32) pp:15822-15828
Publication Date(Web):June 30, 2011
DOI:10.1021/jp203317d
An individual gold nanorod as an optical antenna to modulate single-molecule fluorescence spontaneous emission behaviors is investigated theoretically. 2D and 3D numerical finite-difference time-domain methods are implemented to investigate changes in the excitation rate, spontaneous emission rate, quantum efficiency, and emission spectral shape as functions of the separation between the emitter and nanorod. Our simulations reveal that the 3D relative configuration between the gold nanorod and the single dipole definitely affects the quantum efficiency and emission spectral shape. The orientation of the dipole and the polarization of the excitation light are also investigated to clarify the polarization dependence of the plasmonic-enhanced fluorescence. Furthermore, we calculate the modified quantum efficiency and emission spectral shape of a single Cy5 dye molecule in the vicinity of a single gold nanorod taking experimental requirements into account.
Co-reporter:Shiyong Zhang, Zhijian Chen, Lixin Xiao, Bo Qu, Qihuang Gong
Solar Energy Materials and Solar Cells 2011 95(3) pp: 917-920
Publication Date(Web):
DOI:10.1016/j.solmat.2010.11.021
Co-reporter:Guowei Lu ; Lei Hou ; Tianyue Zhang ; Wenqiang Li ; Jie Liu ; Pascal Perriat
The Journal of Physical Chemistry C 2011 Volume 115(Issue 46) pp:22877-22885
Publication Date(Web):October 14, 2011
DOI:10.1021/jp2081066
We perform a theoretical investigation of individual and coupled gold nanorods as plasmonic nanosensors using the finite-difference time-domain method. Key features of single-nanorod sensors are discussed. The sensitivity distribution of an individual nanorod is anisotropic. The characteristic sensitivity decay length of a single-nanorod sensor is comparable to its diameter. Plasmonic sensing abilities are additive, so analyte-detection sensitivity is not affected by substrates or surface treatments; shifts caused by analytes are only determined by their positions relative to the sensor. Coupled nanorods enhance and concentrate plasmonic sensitivities, and the sensitivity within the gap can be over an order of magnitude higher than that at the nanorod cylinder. The sensitivities of coupled nanorods are only higher than those of individual nanorods when the analytes are anchored within the gaps between nanorods. The calculations show that a single biological molecule can be detected by optimizing nanostructure design and surface treatments to anchor analytes locally on high-sensitivity areas of the sensor surface. Our simulation results assist the design and optimization of plasmonic nanosensors, using single or coupled nanorods.
Co-reporter:Jiaxiu Luo, Lixin Xiao, Zhijian Chen, Bo Qu, Qihuang Gong
Organic Electronics 2010 Volume 11(Issue 4) pp:664-669
Publication Date(Web):April 2010
DOI:10.1016/j.orgel.2010.01.007
The insertion of thin MnO layer between organic photoactive layer and metal electrode significantly improved the power conversion efficiency (PCE) and the air stability of organic photovoltaic cell (OPV). PCE (2.91%) was obtained by inserting 3-nm-thick MnO, higher than 0.91% for the device without MnO, and 2.59% for the device with 0.5-nm-thick LiF. In addition, the PCE of MnO device retained 28.42% of initial value after 2 weeks while the device without MnO dropped down to only 6.03% just after 2 days, even better than that of LiF device which dropped down to 7.29% of initial value after 2 weeks without encapsulation. Insulator MnO is promising to improve the electron transport and operation stability in OPVs.
Co-reporter:Sheng Kong, Lixin Xiao, Zhijian Chen, Xingzhong Yan, Bo Qu, Shufeng Wang and Qihuang Gong
New Journal of Chemistry 2010 vol. 34(Issue 2) pp:325-330
Publication Date(Web):09 Dec 2009
DOI:10.1039/B9NJ00453J
Soluble 5-(cholesteryloxy)methyl-8-hydroxyquinoline lithium(I) (LiChQ) was synthesized through the modification of 8-hydroxyquinoline lithium (LiQ) with cholesterol, and showed about 3 times more enhanced luminescence than pristine LiQ. When increasing the concentration of LiChQ up to 1 wt% in non-protic solvents, nanoscale fibers of 30–100 nm diameter were formed through self-assembly in a super-gel state. There was a red shift in the absorption of the gel in comparison to the solution, which indicates that LiChQ tends to form a J-aggregate in the gel state. We also investigated the gelation process of LiChQ using the Lippert–Mataga equation. We suggest that LiChQ has potential applications in luminescent devices and/or as a template for nanostructured optoelectronic materials.
Co-reporter:Zhifeng Wu, Chengyin Wu, Xianrong Liu, Yongkai Deng and Qihuang Gong, Di Song and Hongmei Su
The Journal of Physical Chemistry A 2010 Volume 114(Issue 25) pp:6751-6756
Publication Date(Web):June 2, 2010
DOI:10.1021/jp1018197
In intense femtosecond laser fields, molecules could be tunnel ionized from multiple valence orbitals, which produces molecular ions in different electronic states. In this article, we have used a reaction microscope to study double ionization of nitrogen by intense femtosecond laser pulses. It is found that some doubly charged molecular ions N22+ are metastable while others dissociate through charge symmetric dissociation (N22+ → N+ + N+) or charge asymmetric dissociation (N22+ → N2+ + N). The kinetic energy releases and angular distributions of atomic ions are measured for the dissociation channels. With the aid of the CASSCF and MRCI calculations, the electronic states are identified and the contributions of the valence orbitals are discussed for these dissociated molecular dications.
Co-reporter:Fei Wang, Zhijian Chen, Lixin Xiao, Bo Qu, Qihuang Gong
Solar Energy Materials and Solar Cells 2010 94(7) pp: 1270-1274
Publication Date(Web):
DOI:10.1016/j.solmat.2010.03.023
Co-reporter:QiHuang Gong;XiaoYong Hu;Hong Yang;ShuFeng Wang
Science Bulletin 2010 Volume 55( Issue 20) pp:2111-2117
Publication Date(Web):2010 July
DOI:10.1007/s11434-010-3183-7
In the twentieth century, revolutionary changes took place in the human society and people’s life-style due to the improvement of the optoelectronic information technology based on the second-order nonlinear optical effects, such as the electro-optic effect, the second harmonic generation (SHG), and so on. Along with the rapid development of light information technology, new principles and methods of nonlinear optics are needed, and the third-order nonlinear optical effects attract great attention. The research progress of nonlinear optics is reviewed in this article. Our research work on the third-order nonlinear optical materials, ultrafast and low-power organic all-optical photonic crystal switching are introduced.
Co-reporter:Kang Meng, Qing Ding, Shufeng Wang, Youjun He, Yongfang Li and Qihuang Gong
The Journal of Physical Chemistry B 2010 Volume 114(Issue 8) pp:2602-2606
Publication Date(Web):February 8, 2010
DOI:10.1021/jp909271e
We report herein the photophysics of three two-dimensional polythiophene derivatives, with different lengths of thienylene−vinylene conjugated side chains, in comparison with regioregular poly(3-hexylthiophene) (P3HT). In solution, an evolution from stimulated emission to photoinduced absorption (PIA) at emission peak is discovered with increasing length of side chains, indicating larger steric hindrance by longer side chains. The exciton lifetime is reduced by a factor of five when the thienylene−vinylene side chain is prolonged to three units. In the film form, we investigate the dynamics of the two PIA bands, assigned to intrachain exciton and interchain polaron pairs, respectively. The analysis of the dynamics suggests that their intrachain exciton decays are similar to the one-dimensional P3HT. The recombination possibility of delocalized interchain polaron pairs occurring in 0.9 ps is reduced with longer thienylene−vinylene side chain samples. Compared with regioregular P3HT film, which self-organizes to form lamellae crystal morphology, the morphologies of these three two-dimensional polythiophenes are amorphous, attributed to the large steric hindrance caused by the existence of side chains. This design of polythiophene derivatives provides the reduction of recombination possibility for delocalized interchain polaron pairs generated in the polymer.
Co-reporter:Kang Meng, Yingliang Liu, Wenke Feng, Qi Zeng, Xiangjie Zhao, Shufeng Wang, Qihuang Gong
Journal of Photochemistry and Photobiology A: Chemistry 2010 Volume 210(Issue 1) pp:44-47
Publication Date(Web):5 February 2010
DOI:10.1016/j.jphotochem.2009.12.007
The steady-state and transient photophysics of a series of newly synthesized phenothiazine-based conjugated polymers and copolymers with thiophene and furan moieties in solvents were investigated. Positive solvatochromism in emission spectra was observed in polar solvents due to excited-state intramolecular charge-transfer. The picosecond time-resolved spectra using streak camera revealed fast chain twisting motion at ∼10 ps, verified by solvent viscosity dependency. A non-radiative de-activate pathway is assigned to the non-planar conformation at excited state. This reveals a possible way for intramolecular energy loss in new polymer design for applications.
Co-reporter:Ying Gu;Jia Li;Olivier J. F. Martin
Science Bulletin 2010 Volume 55( Issue 24) pp:2608-2617
Publication Date(Web):2010 August
DOI:10.1007/s11434-010-4023-5
With the development of nanotechnology, many new optical phenomena in nanoscale have been demonstrated. Through the coupling of optical waves and collective oscillations of free electrons in metallic nanostructures, surface plasmon polaritons can be excited accompanying a strong near field enhancement that decays in a subwavelength scale, which have potential applications in the surface-enhanced Raman scattering, biosensor, optical communication, solar cells, and nonlinear optical frequency mixing. In the present article, we review the Green’s matrix method for solving the surface plasmon resonances and near field in arbitrarily shaped nanostructures and in binary metallic nanostructures. Using this method, we design the plasmonic nanostructures whose resonances are tunable from the visible to near-infrared, study the interplay of plasmon resonances, and propose a new way to control plasmonic resonances in binary metallic nanostructures.
Co-reporter:Yun-Feng Xiao;Chang-Ling Zou;Yan Li
Frontiers of Optoelectronics 2010 Volume 3( Issue 2) pp:109-124
Publication Date(Web):2010 June
DOI:10.1007/s12200-010-0003-2
Asymmetric resonant cavities (ARCs) with smoothly deformed boundaries are currently under intensive study because they possess distinct properties that conventional symmetric cavities cannot provide. On one hand, it has been demonstrated that ARCs allow for highly directional emission instead of the in-plane isotropic light output in symmetric whispering-gallery cavities, such as microdisks, microspheres, and microtoroids. On the other hand, ARCs behave like open billiard system and thus offer an excellent platform to test classical and quantum chaos. This article reviews the recent progresses and prospects for the experimental realization of ARCs, with applications toward highly directional microlasing, strong-coupling light-matter interaction, and highly sensitive biosensing.
Co-reporter:Ziyao Wang, Zhijian Chen, Lixin Xiao, Qihuang Gong
Organic Electronics 2009 Volume 10(Issue 2) pp:341-345
Publication Date(Web):April 2009
DOI:10.1016/j.orgel.2008.12.008
A stable self nano-aggregated bathocuproine film was fabricated and introduced atop of a conventional organic light emitting diode for enhancing top emission. It leads to a 2.7–2.1-fold enhancement on top emission at applied voltage from 4 to 9 V which is much larger than the 1.5–1.3-fold enhancement for a device overlaid with an amorphous bathocuproine film. The more effective outcoupling of this method probably arises from surface plasmon modes being scattered by only the nanostructured surface, and thus without phase cancellation, at the bathocuproine/air boundary. Moreover, this method nearly preserves the original electroluminescent spectra and has no damage on electrical properties.
Co-reporter:Qingqing Liang, Chengyin Wu, Zhifeng Wu, Min Liu, Yongkai Deng, Qihuang Gong
International Journal of Mass Spectrometry 2009 Volume 286(Issue 1) pp:28-31
Publication Date(Web):1 September 2009
DOI:10.1016/j.ijms.2009.06.004
We experimentally study the ionization, fragmentation and Coulomb explosion of CO using 6 fs laser pulses. Different from previous observations in tens or hundreds of femtoseconds laser pulses, strong charge asymmetric dissociation and CO2+ are observed in the current intense few-cycle laser field.Mass spectra of CO irradiated by 6 fs linearly polarized laser pulses at an intensity of 2 × 1015 W/cm2. Strong charge asymmetric dissociation (2, 0) is observed in the current intense few-cycle laser field.
Co-reporter:Min Liu, Chengyin Wu, Zhifeng Wu, Qingqing Liang, Yongkai Deng, Qihuang Gong, Yue Sun, Yuntao Xu, Yujie Zhao, Xiaobin Shan, Fuyi Liu, Liusi Sheng
Chemical Physics Letters 2009 Volume 468(4–6) pp:153-157
Publication Date(Web):22 January 2009
DOI:10.1016/j.cplett.2008.12.047
We experimentally investigate the ionization and dissociation of two isomers, methyl acetate (CH3COOCH3) and ethyl formate (CH3CH2COOH), irradiated by strong laser pulses with a pulse duration of 7 fs. Strong parent ions are observed for both isomers. However, main fragmental ions are CH3CO+ and CH3+ for methyl acetate and CH3O+ and C2H4+ for ethyl formate. Through comparing with the single photon ionization mass spectra of these two isomers, we find that these fragments are produced by the direct dissociation of the parent ions in different excited electronic states.Mass spectra of (a) methyl acetate and (b) ethyl formate irradiated by 7 fs laser pulse at an intensity of 1.0 × 1014 W/cm2.
Co-reporter:Quanshui Li;Chunling Liu;Jining Gao
Journal of Nanoparticle Research 2009 Volume 11( Issue 4) pp:
Publication Date(Web):2009 May
DOI:10.1007/s11051-008-9532-7
In order to reveal the optical limiting mechanisms of semiconductor hollow spheres, the nonlinear optical properties of CuS and Cu2O hollow spheres were investigated via the fluence-dependent transmittance and the nonlinear scattering measurements. The CuS and Cu2O hollow spheres have similar morphologies and different types of optical band-gap. The experimental results show that the optical limiting performance of CuS is better than that of Cu2O, although the nonlinear scattering of Cu2O is stronger than that of CuS. Free-carrier absorption based on the delocalized carriers (holes) in CuS is believed to play an important role in the optical limiting effects. The merits of the structure of semiconductor hollow spheres used for optical limiting were discussed.
Co-reporter:Chengyin Wu, Guiping Zeng, Hongyan Jiang, Yunan Gao, Nan Xu and Qihuang Gong
The Journal of Physical Chemistry A 2009 Volume 113(Issue 40) pp:10610-10618
Publication Date(Web):September 11, 2009
DOI:10.1021/jp905743v
We study the rotational wave packet created by nonadiabatic rotational excitation of molecules with strong femtosecond laser pulses. The applicable condition of the Delta−Kick method is obtained by comparing the laser intensity and pulse duration dependences of the wave packet calculated with different methods. The wave packet evolution is traced analytically with the Delta−Kick method. The calculations demonstrate that the rotational populations can be controlled for the rotational wave packet created by two femtosecond laser pulses. The evolution of the rotational wave packet with controlled populations produces interference patterns with exotic spatial symmetries. These calculations are validated by comparing the theoretical calculations with our experimental measurements for the rotational wave packet created by thermal ensemble CO2 and two strong femtosecond laser pulses. Potential applications in molecular science are also discussed for the rotational wave packet with controlled populations and spatial symmetries.
Co-reporter:Qingqing Liang, Chengyin Wu, Zhifeng Wu, Min Liu, Yongkai Deng, Qihuang Gong
Chemical Physics 2009 360(1–3) pp: 13-17
Publication Date(Web):12 June 2009
DOI:10.1016/j.chemphys.2009.04.002
We experimentally studied the pulse duration effects on the mass spectra of ethylene in intense laser fields. At an intensity of 1.3 × 1014 W/cm2, parent ions C2H4+ are dominant for both 6.4 fs and 110 fs laser pulses. However, strong H+ ion signal is observed only in the 110 fs laser pulse. It is absent in the 6.4 fs laser pulse. When the laser intensity is 6.2 × 1014 W/cm2, singly and doubly charged parent ions are observed for both 6.4 fs and 110 fs laser pulses. In addition, some highly charged carbon ions are present for 110 fs laser pulses. However, these highly charged carbon ions are replaced by some other singly and doubly charged fragmental ions for 6.4 fs laser pulses. The above different mass spectra for ethylene are explained by the nuclear motion assisted by the strong laser fields with different pulse durations.
Co-reporter:Saisai Chu, Wenhui Yi, Shufeng Wang, Fengming Li, Wenke Feng, Qihuang Gong
Chemical Physics Letters 2008 Volume 451(1–3) pp:116-120
Publication Date(Web):17 January 2008
DOI:10.1016/j.cplett.2007.11.087
Charge-transfer composite material, poly-1-methoxy-4-octoxy-(para-phenelene vinylene) (MO-PPV) wrapped single wall carbon nanotubes (SWNTs), MO-PPV/SWNTs, was synthesized by in situ polymerization. Photophysics properties of MO-PPV/SWNTs were studied by using steady-state spectra, femtosecond fluorescence up-conversion technique, and streak camera. Compared with the pure MO-PPV in solution, fluorescence quenching was observed. Photoinduced electron-transfer from MO-PPV to SWNTs occurs on femtosecond timescale, while photoinduced intermolecular energy-transfer appears at ∼100 ps timescale.Static and transient researches on MO-PPV/SWNTs reveal ultrafast intermolecular electron-transfer. Slower exciton migration was also observed.
Co-reporter:Saisai Chu, Fengming Li, Haizheng Tao, Hong Yang, Shufeng Wang, Changgui Lin, Xiujian Zhao, Qihuang Gong
Optical Materials 2008 Volume 31(Issue 2) pp:193-195
Publication Date(Web):October–December 2008
DOI:10.1016/j.optmat.2008.03.002
GeS2 based multi-component chalcogenide glasses, Ge–S–Sb(Cd), were prepared in series. With femtosecond time-resolved optical Kerr gate technique, we investigate their ultrafast third-order nonlinear optical (NLO) properties. The strongest NLO response comes from 0.70GeS2–0.30Sb2S3. Its χ(3), 1.8 × 10−12 esu, is more than three times to GeS2 glass. Their instant NLO responses are within 120 fs pulse duration. We suggest that lone-pair electrons from highly polarizable Sb atom in [SbS3] structure unit play an important role for the enhanced NLO response. This enhancement is much stronger to the contribution from S–S covalent bond.
Co-reporter:Lisheng Wang, Jiasen Zhang, Xiaofei Wu, Jing Yang, Qihuang Gong
Optics Communications 2008 Volume 281(Issue 21) pp:5444-5447
Publication Date(Web):1 November 2008
DOI:10.1016/j.optcom.2008.07.032
Co-reporter:Bo Qu, Zhijian Chen, Feng Xu, Huayu Cao, Zhihao Lan, Ziyao Wang, Qihuang Gong
Organic Electronics 2007 Volume 8(Issue 5) pp:529-534
Publication Date(Web):October 2007
DOI:10.1016/j.orgel.2007.03.009
A novel red–orange emitting material with a branched molecular structure, 2,4,6-tris[2-(N-ethyl-3-carbazole)carboxethenyl]-1,3,5-s-triazine (TC3), has been synthesized and characterized using UV–visible, photoluminescence (PL) and electroluminescence (EL) spectroscopy. White EL devices were fabricated using TC3 as a red–orange emitter and 8-hydroxyquinolinolato lithium (Liq) as a blue–green emitter. N,N-bis(3-methylphenyl)-N,N-diphenylbenzidine (TPD) as the adjustor for charge carrier mobility was introduced between the two emitting layers to improve the stability of the white emission color on bias voltage. The EL devices of ITO/poly(N-vinylcarbazole) (PVK):TC3 (56 nm)/TPD (5 nm)/Liq (30 nm)/Mg:Ag exhibited good quality white emission. The Commission Internationale De L’Eclairage chromaticity coordinates are (0.34, 0.39) and are stable on the bias voltage.
Co-reporter:Huayu Cao, Zhijian Chen, Yingliang Liu, Bo Qu, Shengang Xu, Shaokui Cao, Zhihao Lan, Ziyao Wang, Qihuang Gong
Synthetic Metals 2007 Volume 157(10–12) pp:427-431
Publication Date(Web):June 2007
DOI:10.1016/j.synthmet.2007.04.014
The single layer and multilayer undoped light-emitting devices were fabricated using a new soluble phenothiazine-based derivative, poly(3,7-N-octyl phenothiozinyl terephthalylidene) (POPTP). Through the optimization of device structures, the multilayer device has a maximum luminance of 1203 cd/m2 at the bias voltage of 9.3 V, using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) as a hole-blocking layer and tris-(8-hydroxyquinoline)aluminium (Alq3) as a electron-injection/transporting layer. The Commision International de L’Eclairage (CIE) coordinates stabilized at (x, y) = (0.46, 0.53) at various bias voltages. Additionally, the dominant wavelength (λD) of around 575 nm and the color purity of approximately 100% indicated a pure yellow emission property. Therefore, POPTP is a stable candidate material with a pure yellow emission for the undoped organic light-emitting diodes (OLEDs).
Co-reporter:Feng Xu, Zhenwei Wang, Qihuang Gong
Optical Materials 2007 Volume 29(Issue 6) pp:723-727
Publication Date(Web):February 2007
DOI:10.1016/j.optmat.2005.12.003
The octupolar molecule with s-triazine as the π-electron deficient core, N-ethylcarbazole groups as the electron-donating end-groups, 2,4,6-tris[2-(N-ethyl-3-carbazole)carboxethenyl]-1,3,5-s-triazine(III), was prepared. The assemblies of III, 2,4-dimethyl-6-[2-(N-ethyl-3-carbazole)carboxethenyl]-1,3,5-s-triazine(I), and 2-methyl-4,6-bis [2-(N-ethyl-3-carbazole)carboxethenyl]-1,3,5-s-triazine(II), were also prepared. The linear and nonlinear spectra of these compounds regularly vary: (1) the spectral positions (λmax values) of the linear absorption, the one-photon excited fluorescence (OPEF) and the two-photon excited fluorescence (2PEF) show regular red-shifts when the branch number increases from I to III; (2) the OPEF and the 2PEF intensities are all increased significantly when going from I to III. Excited by femtosecond laser at 800 nm wavelength, the fluorescence intensities of II, III show a quadratic dependence on the pump intensity, suggesting that the emission originates from a 2PA process. Two-photon absorption (2PA) cross-section of II, III is 397 GM and 994 GW, respectively. The value of σ2/MW of II, III varies with the ratio of 1.0:1.8.
Co-reporter:Yingliang Liu;Huayu Cao;Jianghui Li;Shaokui Cao;Zhijian Chen;Shengang Xu;Lixin Xiao
Journal of Polymer Science Part A: Polymer Chemistry 2007 Volume 45(Issue 21) pp:4867-4878
Publication Date(Web):14 SEP 2007
DOI:10.1002/pola.22237
A novel phenothiazine-based polymer was synthesized through the Heck reaction of 3,7-divinyl-N-octyl-phenothiazine with 4,7-dibromo-2-octylbenzotriazole according to the alternating donor–acceptor strategy. The polymer was characterized with 1H NMR, infrared spectroscopy, gel permeation chromatography, cyclic voltammetry, ultraviolet–visible spectroscopy, and fluorescence spectroscopy. With the polymer used as an active layer, three nondoped polymer light-emitting diodes (PLEDs) with a double-layer configuration were fabricated by the spin-coating approach with different thermal annealing processes. The emission maximum in electroluminescent spectra was stabilized at 616 nm. The maximum luminance reached 2432 cd/m2. The coordinate value of Commission International de l'Eclairage 1931 in the double-layer PLEDs after the thermal treatment was nearly stabilized at (x, y) =(0.62, 0.38). Additionally, the luminous efficiency of device II reached a balanceable state with an increase in the current. Therefore, the polymer had an orange-red emission with stable chromaticity coordinates under different driving voltages. Finally, a nondoped device with a stable luminous efficiency and chromaticity was obtained. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4867–4878, 2007
Co-reporter:Yang Cong, Zhijian Chen, Fushan Li, Qihuang Gong
Optical Materials 2006 Volume 28(8–9) pp:1084-1087
Publication Date(Web):June 2006
DOI:10.1016/j.optmat.2005.05.017
We proposed a white light-emitting diode based on a dendritic polyfluorene derivative poly((9,9-dibutyl-2,7-diiodo-9H-fluorene)trisphenylamine) (PDFA) as blue-green emitter and doped it with a fluorescent dye 4-dicyanomethylene-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM) as red emitter. White light was achieved by the incoherent superposition of blue-green emission produced from PDFA and red emission from DCM. The Commission Internationale d’Énclairage chromaticity coordinates of the devices varied from (0.19, 0.22) to (0.39, 0.55) with the increase of DCM concentration (from 0 to 0.2 wt.%).
Co-reporter:Bo Qu, Zhijian Chen, Feng Xu, Huayu Cao, Maomao Huang, Qihuang Gong
Materials Letters 2006 Volume 60(Issue 15) pp:1927-1930
Publication Date(Web):July 2006
DOI:10.1016/j.matlet.2005.12.056
A novel green emitting material of 2,4,6-Tristriphenylamine-1,3,5-s-triazine (TT3) was synthesized and the organic light-emitting diodes of indium tin oxide (ITO)/TT3/ biphasic calcium phosphate (BCP)/Mg:Ag based on TT3 as the hole transporting and emitting layer were fabricated. The electroluminescent properties were studied. The devices gave pure and bright green light emission peaked at 513 nm and the full width at half maximum of the emission was narrowed by 13.2% compared with the typical green EL device of ITO/TPD:PVK/tris(8-hydroxyquinolinato)aluminium/Mg:Ag, and the brightness was higher than that of the typical device at the same voltage.
Co-reporter:Fushan Li, Zhijian Chen, Wei Wei, Qihuang Gong
Organic Electronics 2005 Volume 6(5–6) pp:237-241
Publication Date(Web):December 2005
DOI:10.1016/j.orgel.2005.08.002
Polymer double-layer light-emitting diodes were fabricated with inorganic/organic hybrid composite as hole transporting layer. Two conjugated polymers, poly(9,9-dibutyl)fluorene (PDF) and a dendritic polyfluorene derivative, poly((9,9-dibutyl-2,7-diiodo-9H-fluorene)trisphenylamine) (PDFA) were introduced as light-emitting layer. The former organic double-layer devices showed luminance as high as 833 lm/m2, and the power efficiency reached 0.065 lm/W. The latter showed maximum luminance of 1100 lm/m2 and the quantum efficiency reached 0.104 lm/W. The values were higher than those single-layer devices without inorganic/organic hybrid hole transporting layer (HHTL). The improvement in the electroluminescent properties of these devices was attributed to that the introduction of HHTL enhanced hole injection and balanced the combination of hole and electron injected from anode (ITO) and cathode (Mg:Ag).
Co-reporter:Xiaoyong Hu, Qihuang Gong, Shuai Feng, Bingying Cheng, Daozhong Zhang
Optics Communications 2005 Volume 253(1–3) pp:138-144
Publication Date(Web):1 September 2005
DOI:10.1016/j.optcom.2005.04.056
A tunable filter with multichannel is proposed based on a nonlinear ferroelectric photonic crystal made of rhodium doped barium titanate. The filtering properties of the photonic crystal filter, including channel number and frequency, can be tuned by adjusting the thickness of defect layer or by pump light. The dynamical shift of channels with pump intensity is studied in detail. The channel shifts about 90 nm under the excitation of 75 MW/cm2 pump light. The influences of structural disorders caused by random perturbations in the thickness of dielectric layer or air layer on the photonic crystal filter are analyzed.
Co-reporter:Hong Xiang, Dongfang Liu, Zhenwei Wang, Zhi Li, Wentao Huang, Hong Yang, Zhixin Guo, Qihuang Gong
Chemical Physics Letters 2004 Volume 392(1–3) pp:80-84
Publication Date(Web):1 July 2004
DOI:10.1016/j.cplett.2004.05.026
Abstract
The ultrafast third-order optical nonlinearity of two C60 derivatives was measured by using the optical Kerr effect (OKE) at 830 nm wavelength, with laser pulse duration of 115 fs. Tremendous difference in OKE responses was observed due to the different attached bond site. For the [5,6]azafulleriod, a supposition was suggested and the large OKE response of solution subtracting from the contribution of solvent was obtained and its second-order hyperpolarizability γ was deduced as large as 2.9 × 10−31 esu, which is three orders of magnitude larger than the value of C60. While, for the [6,6]azafullerene, no any enhancement is observed in comparing with that of C60.
Co-reporter:Tieqiao Zhang, Shufeng Wang, Hong Yang, Wentao Huang, Qihuang Gong, Keitaro Yoshihara, Qian Wang, Jiagang Luo, Huiying Chen
Journal of Luminescence 2003 Volume 101(1–2) pp:161-166
Publication Date(Web):January 2003
DOI:10.1016/S0022-2313(02)00409-X
The photoluminescence dynamics of a new polymer, (–CN–) conjugated polybenzonitrile, was investigated with a femtosecond time-resolved fluorescence up-conversion technique. The experimental results revealed a bi-exponential relaxation dynamics for excited state and it was explained with the photo-generated excitons’ migration model.
Co-reporter:Zhijian Chen, Feng Wang, Bo Zhang, Hui Liu, Qihuang Gong, Yaowen Bai, Yiwang Chen, Xiaofang Chen, Xinhua Wan, Qifeng Zhou, Huiying Chen
Optical Materials 2003 Volume 23(1–2) pp:253-259
Publication Date(Web):July–August 2003
DOI:10.1016/S0925-3467(02)00297-5
The organic photorefractive (PR) materials and devices have attracted much interest due to the wide potential applications. In this talk, we report the recent study on PR materials and PR physical property in our group. To overcome the disadvantages (e.g. instability and critical environment requirement) of the multi-component PR composite, two novel three-component PR systems were fabricated based on a series of azo dyes and liquid crystals as both EO chromophore and plasticizer, respectively, and the excellent PR performances were obtained. More recent, mono-component PR sample based on a fully functional polymer, poly(9-(2-ethyl-hexyl)-3-[2-(4-methanesulfonyl-phenyl)vinyl]-9H-carbazole), was reported to exhibit two-beam coupling coefficient more than 100 cm−1 at 632.8 nm wavelength at applied electric field of 100 V/μm. The fast response time was obtained from composite doped with β,β-diacetyl-4-methoxylstyrene (DAMST). Besides, DAMST also is the more suitable selection to operate at short wavelength.
Co-reporter:Wentao Huang, Hong Xiang, Qihuang Gong, Yanyi Huang, Chunhui Huang, Jianzhuang Jiang
Chemical Physics Letters 2003 Volume 374(5–6) pp:639-644
Publication Date(Web):18 June 2003
DOI:10.1016/S0009-2614(03)00785-1
The third-order optical nonlinearity of two triple-decker mixed phthalocyaninato and porphyrinato Sm complexes, Sm2(Pc)2(TPP) and Sm2(Pc)(TPP)2 (Pc=phthalocyanine; TPP=5,10,15,20-tetraphenylporphyrinate), is investigated using the femtosecond time-resolved optical Kerr gate method at 830 nm wavelength. Their second-order hyperpolarizabilities are estimated to be 2.6 × 10−30 and 2.2 × 10−30 esu, respectively. Introducing of Lanthanide Sm to the large π-conjugated system, intermacrocycle interaction and two-photon resonance are considered responsible for the large optical nonlinearity.
Co-reporter:X.Y Pan, N.V Chigarev, H.B Jiang, W.T Huang, Qihuang Gong, C.L Liu, V.M Kobryanskii, D.Yu Paraschuk
Chemical Physics Letters 2002 Volume 365(1–2) pp:117-121
Publication Date(Web):28 October 2002
DOI:10.1016/S0009-2614(02)01376-3
The third-order optical non-linearity was measured in nanopolyacetylene using femtosecond optical Kerr effect technique at wavelength from 790 to 860 nm. The ultrafast non-resonant effective second-order hyperpolarizibility for single polyacetylene nanoparticle was estimated to be as large as 1.0×10−27 esu, which corresponding to the γc of single carbon atom contribution equals to 5.0×10−33 esu. We ascribed the observations to the highly ordered structure of nanopolyacetylene and delocalization of the π electrons along the conjugated chains was supposed to be responsible for such properties.
Co-reporter:N.V. Chigarev, X.Y. Pan, Qihuang Gong, D.Yu. Paraschuk, V.M. Kobryanskii
Optics Communications 2002 Volume 209(4–6) pp:363-367
Publication Date(Web):15 August 2002
DOI:10.1016/S0030-4018(02)01671-1
The polarization response of neutral sub-gap photoexcited states in nonoriented nanopolyacetylene films was measured using a femtosecond photoinduced polarimetry technique. We show that the observed polarization signals are associated with a linear dichroism in the photoexcited state of trans-nanopolyacetylene. The characteristic decay time of the polarization signals was 1.4 ps. At the same time, we conclude that the photoinduced anisotropy persists up to 10 ps and therefore the photoexcited π electrons are highly delocalized along the polymer chains.
Co-reporter:C. Liu;X. Wang;Q. Gong;K. Tang;X. Jin;H. Yan;P. Cui
Advanced Materials 2001 Volume 13(Issue 22) pp:
Publication Date(Web):30 OCT 2001
DOI:10.1002/1521-4095(200111)13:22<1687::AID-ADMA1687>3.0.CO;2-H
Co-reporter:Chunling Liu, Xin Wang, Qihuang Gong, Yunqi Liu, Wenfeng Qiu, Daoben Zhu
Chemical Physics Letters 2001 Volume 347(4–6) pp:378-382
Publication Date(Web):26 October 2001
DOI:10.1016/S0009-2614(01)01058-2
A novel conjugated phthalocyanine pentamer was studied for optical limiting performance. Its fluence-dependent transmittance in different solvents was measured using 10 ns, 532 nm laser pulses in a collimated optical setup. Compared with in chloroform, phthalocyanine pentamer dissolved in chloroform/methyl iodide mixed solvent shows better optical limiting performance at the same linear transmittance. Explanation based on the triple-state absorption enhanced by the increase of the intersystem crossing rate through external heavy atom effect was proposed.
Co-reporter:Wentao Huang, Shufeng Wang, Hong Yang, Qihuang Gong, Xiaowei Zhan, Yunqi Liu, Daoben Zhu
Chemical Physics Letters 2001 Volume 350(1–2) pp:99-105
Publication Date(Web):14 December 2001
DOI:10.1016/S0009-2614(01)01220-9
A femtosecond time-resolved optical Kerr gate method, using 115 fs laser pulses at 830 nm, has been applied to investigate the third-order nonlinearity of two novel copolymers containing fluorene and tetraphenyldiaminobiphenyl units in their backbones. Ultrafast off-resonant optical Kerr responses have been observed and the magnitude of the second-order hyperpolarizability was measured as large as 10−30 esu. The origin of the extraordinary large value was explored and compared to other organic materials.
Co-reporter:Xin Wang, Chunling Liu, Qihuang Gong, Yanyi Huang, Chunhui Huang
Optics Communications 2001 Volume 197(1–3) pp:83-87
Publication Date(Web):15 September 2001
DOI:10.1016/S0030-4018(01)01413-4
Optical limiting (OL) performance of two homoleptic sandwich-type lanthanide diphthalocyanines, M[Pc(OC5H11)8]2 (M=Gd, Eu), was investigated via fluence-dependent transmittance measurements. The measurements were performed using collimated 10-ns pulses generated from a frequency-doubled Nd:YAG laser at 532-nm wavelength. The results indicated that Eu[Pc(OC5H11)8]2 exhibited better OL performance than Gd[Pc(OC5H11)8]2, which seems to be contrary to the heavy atom effect because the gadolinium ion is heavier than europium ion. A possible explanation was proposed that, not only the atomic number but also the ion radius of the metal center would influence the OL performance of metal diphthalocyanines.
Co-reporter:Liang-You Peng, Wei-Chao Jiang, Ji-Wei Geng, Wei-Hao Xiong, Qihuang Gong
Physics Reports (18 April 2015) Volume 575() pp:1-71
Publication Date(Web):18 April 2015
DOI:10.1016/j.physrep.2015.02.002
In this review, we will focus on the theoretical aspects in observing and controlling the electronic dynamics in few-electron atoms and molecules by attosecond pulses in different circumstances. In particular, we will first review the main theoretical methods and concepts in strong field and attosecond physics, and then discuss a number of topics including generation of xuv light sources, the probe and steering of the electron motion in the combination of xuv and IR pulses, the photoionization time delay, the electron–electron correlation dynamics in multiple-electron atoms and molecules, etc. Although the present review mainly concentrates on the theoretical aspects, in each section we will also give a brief account of the related experimental implications and implementations for those which have been demonstrated so far or which will be experimentally feasible in the near future.
Co-reporter:Lixin Xiao, Boyuan Qi, Xing Xing, Lingling Zheng, Sheng Kong, Zhijian Chen, Bo Qu, Lipei Zhang, Ziwu Ji and Qihuang Gong
Journal of Materials Chemistry A 2011 - vol. 21(Issue 47) pp:NaN19062-19062
Publication Date(Web):2011/10/28
DOI:10.1039/C1JM13488D
A high triplet energy (ET = 3.2 eV) electron transporting/hole blocking (ET/HB) material, 1,2,4,5-tetra(3-pyrid-3-yl-phenyl)benzene (TemPPB) with a super twisted structure and high thermal stability has been synthesized. An external quantum efficiency (EQE) of 19.6% was achieved by using TemPPB as the ET/HB material in a blue electrophosphorescent device, much higher than the EQE of 12.5% for the device using the conventional ET material, 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ). In addition, the weak ET property of TemPPB resulting from its super twisted structure can be enhanced via n-type doping with LiF. An EQE of 24.5% was achieved by combining n-type doping and a double-emission layer. This shows an alternative way to design ET/HB materials with high ET and improved thermal stability for blue electrophosphorescent devices.
Co-reporter:Xing Xing, Lixin Xiao, Lingling Zheng, Shuangyuan Hu, Zhijian Chen, Bo Qu and Qihuang Gong
Journal of Materials Chemistry A 2012 - vol. 22(Issue 30) pp:NaN15140-15140
Publication Date(Web):2012/06/07
DOI:10.1039/C2JM32512H
A spirobifluorene derivative containing phenanthrene moiety, 2,7-di(phenanthren-9-yl)-9,9′-spirobifluorene (DPSF), has been synthesized. It shows absorption peaks at 254 nm, 310 nm, and 327 nm and a fluorescence peak at 383 nm in CHCl3 that shifts to 398 nm in the film state. The quantum yield is 0.79 calibrated with a standard of coumarin 102 (0.93). A pure blue emission at Commission Internationale de l′Éclairage (CIE) (0.15, 0.08), has been achieved using DPSF as the emitter, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) as the hole injecting layer, 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino] biphenyl (NPB) as the hole transporting layer, and 1,3,5-tris(N-phenylbenzimidazol-2-yl)-benzene (TPBI) mixing with 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (2:1) as the electron transporting material. The maximum current efficiency (CE) and power efficiency (PE) of the DPSF device are 3.24 cd A−1 and 2.54 lm W−1, corresponding to 5.41% of maximum external quantum efficiency (EQE). The spirobifluorene derivative show high thermal stabilities, 178 °C for the glass transition temperature (Tg) and 503 °C for the decomposition temperature (Td). The synthesized spirobifluorene derivative shows potential application as a highly efficient pure blue emitter for organic light emitting devices (OLED).
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