Co-reporter:Kaiyong Sun, Yibai Sun, Tianyu Huang, Jirong Luo, Wei Jiang, Yueming Sun
Organic Electronics 2017 Volume 42() pp:123-130
Publication Date(Web):March 2017
DOI:10.1016/j.orgel.2016.12.026
•We designed and synthesized two dendrimers TA-Cz and TA-3Cz with TADF characteristics.•The introduction of the phenyl bridge is a promising route to simultaneously achieve small ΔEST and enhanced PLQYs.•Our results here provide a facile strategy to obtain highly efficient non-doped solution-processed OLEDs.We designed and synthesized two dendrimers TA-Cz and TA-3Cz with TADF characteristics by using non-conjugated aliphatic chains carbazole/tricarbazole as peripheral dendrons. Both dendrimers possess excellent thermal and morphological stabilities. Introduced the phenyl bridge to increase the distance of the emission core TA between donor (D) and acceptor (A) is a promising route to simultaneously achieve small singlet–triplet energy splitting (ΔEST) and enhanced PL quantum yields (PLQYs). Furthermore, non-conjugated aliphatic chains carbazole/tricarbazole dendrons were conveniently introduced to the TADF core, which can effective encapsulate the emission core to restrain the concentration quenching effect and make the fluorescence of the core independent. By utilizing TA-3Cz emitter as the non-doped solution-processed emissive layers, the resulting yellow OLED achieved low driving voltage of 2.4 V and superior external quantum efficiency of 11.8%. Thus, our results here provide a facile strategy to obtain highly efficient non-doped solution-processed OLEDs by employing the reasonable molecular design of the TADF core and the utilization of flexible alkyl chain.Our researches present a judicious design strategy for highly efficient non-doped solution-processable TADF emitters by employing the reasonable molecular design of the TADF core and the utilization of flexible alkyl chain.
Co-reporter:Bin Huang, Yigang Ji, Zijing Li, Na Zhou, Wei Jiang, Yan Feng, Baoping Lin, Yueming Sun
Journal of Luminescence 2017 Volume 187(Volume 187) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.jlumin.2017.03.038
•Anthraquinone derivatives have been synthesized via one–step reactions.•These materials simultaneously exhibit AIE and TADF.•The solution–processed red OLEDs exhibited a high EQE of 7.8%.Two simple red–emitting compounds, 2–carbazol–9–yl–anthraquinone (Cz–AQ) and 2–(4–diphenylamino–phenyl)–anthraquinone (TPA–AQ) have been synthesized. The optical, electrochemical and thermal properties of anthraquinone derivatives were systematically characterized. These materials simultaneously exhibit aggregation–induced emission (AIE) and thermally activated delayed fluorescence (TADF). The solution–processed devices using Cz–AQ and TPA–AQ as the dopants exhibit orange and red emission color with peaks at 572 and 612 nm, low turn–on voltage of 3.5 and 3.8 V, maximum current efficiency of 10.8 and 10.6 cd A–1, high external quantum efficiency of 5.8% and 7.8%, maximum luminance of 3200 and 2200 cd m–2, and the Commission Internationale del’Eclairage (CIE) coordinates of (0.50, 0.49) and (0.60, 0.40), respectively. The results may help the design and development of AIE–TADF emitters for high–performance solution–processed OLEDs.Download high-res image (199KB)Download full-size image
Co-reporter:Kaiyong Sun, Yibai Sun, Dan Liu, Yingli Feng, Xusheng Zhang, Yueming Sun, Wei Jiang
Dyes and Pigments 2017 Volume 147(Volume 147) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.dyepig.2017.08.045
•A novel self-host near-infrared TADF dendrimer MPPA-MCBP with four-arm encapsulation was designed and synthesized.•Bipolar MCBP dendrons can effectively reduce the unwanted concentration quenching and the unbalanced charge transfer.•TADF dendrimers with bipolar dendrons will be a feasible approach to develop efficient nondoped solution-processed OLEDs.A self-host thermally activated delayed fluorescence (TADF) dendrimer, namely MPPA-MCBP, for solution-processed nondoped near-infrared organic light-emitting diodes (OLEDs) was designed and synthesized, in which the bipolar CBP derivatives is introduced to render balanced charge transportation. This structural modification that the dendrons are well-bounded by the flexible alkyl chains, which can efficiently reduce the intermolecular interactions between the emissive cores and ensure the stable operation of the solution-processed device. As a result of the spin-coated OLEDs employing MPPA-MCBP as the host-free near-infrared emitter exhibits a highest external quantum efficiency (EQE) of 0.62% and a peak wavelength at 698 nm, which indicates the design of self-host TADF dendrimers containing bipolar dendrons will be a promising strategy to improve the electroluminescent performance of solution-processed nondoped device.Here, a novel self-host TADF dendrimer for solution-processed nondoped near-infrared OLEDs was designed and synthesized, in which the bipolar CBP derivatives is introduced to render balanced charge transportation.Download high-res image (277KB)Download full-size image
Co-reporter:Bin Huang;Zijing Li;Hui Yang;Die Hu;Wenjing Wu;Yan Feng;Yueming Sun;Baoping Lin;Wei Jiang
Journal of Materials Chemistry C 2017 vol. 5(Issue 46) pp:12031-12034
Publication Date(Web):2017/11/30
DOI:10.1039/C7TC04444E
Mechanochromic luminescence (ML), thermally activated delayed fluorescence (TADF), aggregation-induced emission (AIE), and electroluminescence (EL) properties are combined in a single organic molecule, 2-(carbazol-9-yl)-anthraquinone (Cz-AQ). Through controlling film formation in different solvents, the solution-processed nondoped devices utilizing Cz-AQ as the emitter exhibit bicolour emission with peaks at 600 and 680 nm, respectively.
Co-reporter:Bin Huang;Zijing Li;Hui Yang;Die Hu;Wenjing Wu;Yan Feng;Yueming Sun;Baoping Lin;Wei Jiang
Journal of Materials Chemistry C 2017 vol. 5(Issue 46) pp:12031-12034
Publication Date(Web):2017/11/30
DOI:10.1039/C7TC04444E
Mechanochromic luminescence (ML), thermally activated delayed fluorescence (TADF), aggregation-induced emission (AIE), and electroluminescence (EL) properties are combined in a single organic molecule, 2-(carbazol-9-yl)-anthraquinone (Cz-AQ). Through controlling film formation in different solvents, the solution-processed nondoped devices utilizing Cz-AQ as the emitter exhibit bicolour emission with peaks at 600 and 680 nm, respectively.
Co-reporter:Xinxin Ban, Wei JiangKaiyong Sun, Baoping Lin, Yueming Sun
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 8) pp:
Publication Date(Web):February 13, 2017
DOI:10.1021/acsami.6b14922
A self-host thermally activated delayed fluorescence (TADF) dendrimer POCz-DPS for solution-processed nondoped blue organic light-emitting diodes (OLEDs) was designed and synthesized, in which the bipolar phosphine oxide carbazole moiety was introduced by alkyl chain to ensure balanced charge transfer. The investigation of physical properties showed that the bipolar dendrons not only improve the morphological stability but also restrain the concentration quenching effect of the TADF emissive core. The spin-coated OLEDs featuring POCz-DPS as the host-free blue emitter achieved the highest external quantum efficiency (7.3%) and color purity compared with those of doped or nondoped devices based on the parent molecule DMOC-DPS, which indicates that incorporating the merits of encapsulation and bipolar dendron is an effective way to improve the electroluminescent performance of the TADF emitter used for a solution-processed nondoped device.Keywords: bipolar; dendrimer; organic light-emitting diodes; self-host; solution process; TADF;
Co-reporter:Yunqian Dai;Xiaomian Qi;Wanlin Fu;Chengqian Huang;Shimei Wang;Jie Zhou;Tingying Helen Zeng;Yueming Sun
RSC Advances (2011-Present) 2017 vol. 7(Issue 27) pp:16379-16386
Publication Date(Web):2017/03/14
DOI:10.1039/C7RA01188A
Sintering of noble-metal nanoparticles (NPs) presents a major cause for catalyst deactivation as temperature rises. To date, finding simple strategies to develop sinter-resistant catalysts is still a daunting challenge. Herein, we report stable Pt nanoparticles (<3 nm) on porous Fe2O3 nanocrystals using wrinkled graphene sheets as a new stabilizing layer to manipulate their thermal-stability against sintering. Such a catalyst system allows the Pt NPs to achieve significant thermal stability against extremely severe thermal treatment up to 750 °C in both inert and oxidative atmosphere and retain strikingly remarkable activity; this is due to rhombohedral Fe2O3 nanocrystals ensuring the good dispersibility of Pt NPs across the entire surface, and the distinctive wrinkles on graphene sheets acting as new physical barriers. This study inspires a general approach of developing sinter-resistant catalysts with tunable compositions, to maximize the thermal stability and catalytic activity under harsh conditions.
Co-reporter:Kaiyong Sun, Da Chu, Yaodong Cui, Wenwen Tian, Yueming Sun, Wei Jiang
Organic Electronics 2017 Volume 48(Volume 48) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.orgel.2017.06.034
•Two near-infrared TADF dendrimers are reported to develop the non-doped solution-processed OLED for the first time.•The peripheral dendrons of dendrimers can encapsulate the core to prevent concentration quenching.•Our results here provide a facile strategy to obtain highly efficient non-doped solution-processed NIR OLEDs.Two near-infrared (NIR) dendrimers with TADF characteristics are reported to develop the non-doped solution-processed OLED for the first time. The rigid ring end-capped aliphatic chain dendrons are introduced to improve the dissolvability and film-forming ability. The dendrimers possess excellent thermal and morphological stabilities. Simultaneously, the dendrimers exhibit self-host feature that the peripheral carbazole/tricarbazole dendrons can encapsulate the core to prevent concentration quenching. Employing MPPA-3Cz as the emitter, the non-doped solution-processed device exhibits a maximum external quantum efficiency (EQE) of 0.254% with a peak wavelength at 715 nm, which is comparable to the most-efficient solution-processed NIR FOLEDs with similar electroluminescent spectra. Moreover, the device shows negligible efficiency roll-off at high current density. Our results indicate that the design of long-wavelength TADF dendrimers will be a promising strategy for the efficient non-doped solution-processed NIR OLEDs.Our study provides new ideas for the design of efficient non-doped solution-processed near-infrared OLEDs by utilizing the TADF dendrimers.Download high-res image (220KB)Download full-size image
Co-reporter:Kaiyong Sun, Yibai Sun, Wei Jiang, Suli Huang, Wenwen Tian, Yueming Sun
Dyes and Pigments 2017 Volume 139(Volume 139) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.dyepig.2016.12.037
•Thianthrene-9,9′,10,10′-tetraoxide based TADF emitters with various donor units has been synthesized.•The emission spectra of the TADF materials can be fine-tuned from sky-blue to orange-red.•The method is a promising strategy to achieve highly efficient full-color organic light emitting diodes.Here, some luminescent compounds, which comprise a central thianthrene-9,9′,10,10′-tetraoxide acceptor core coupled with various donor units, have been synthesized and reported as thermally activated delayed fluorescent emitters. This set of compounds allows systematic fine-tuning of the band gap that cover the entire visible range from sky-blue to orange-red. The results of optical and electrochemical studies show that their highest occupied molecular orbitals and energy gaps can be easily modified by carefully choosing appropriate donor units. Solution-processed organic light emitting diodes with high maximum external electroluminescence quantum efficiencies of up to 9.1% have been demonstrated by using these emitters. Our results demonstrate the method that systematic tuning the band gap as well as keeping the suitable the lowest unoccupied molecular orbital energy levels of emitters is a promising strategy to achieve highly efficient full-color organic light emitting diodes.Download high-res image (292KB)Download full-size image
Co-reporter:Xinxin Ban, Kaiyong Sun, Yueming Sun, Bin Huang, and Wei Jiang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 3) pp:2010
Publication Date(Web):January 4, 2016
DOI:10.1021/acsami.5b10335
A benzimidazole/phosphine oxide hybrid 1,3,5-tris(1-(4-(diphenylphosphoryl)phenyl)-1H-benzo[d]imidazol-2-yl)benzene (TPOB) was newly designed and synthesized as the electron-transporting component to form an exciplex-type host with the conventional hole-transporting material tris(4-carbazoyl-9-ylphenyl)amine (TCTA). Because of the enhanced triplet energy and electron affinity of TPOB, the energy leakage from exciplex-state to the constituting molecule was eliminated. Using energy transfer from exciplex-state, solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) achieved an extremely low turn-on voltage of 2.8 V and impressively high power efficiency of 22 lm W–1. In addition, the efficiency roll-off was very small even at luminance up to 10 000 cd m–2, which suggested the balanced charge transfer in the emission layer. This study demonstrated that molecular modulation was an effective way to develop efficient exciplex-type host for high performanced PHOLEDs.Keywords: blue emission; exciplex; organic light emitting diode; solution-process; turn-on voltage
Co-reporter:Bo Song, Yuqiao Wang, Xia Cui, Zhaoxia Kou, Lifang Si, Wenwen Tian, Chang Yi, Tao Wei, and Yueming Sun
Crystal Growth & Design 2016 Volume 16(Issue 2) pp:887-894
Publication Date(Web):December 15, 2015
DOI:10.1021/acs.cgd.5b01450
A series of uniformly unique three-dimensional (3D) structures of layered zinc hydroxides (LZHs) were synthesized via a hydrothermal method. During the process, two kinds of LZHs with different crystal structures could be formed, depending on the ionic groups intercalated in zinc hydroxide layers: when carbonate anions were the only interlayer ions, the corresponding LZH compound was assigned as LZHC or zinc hydroxide carbonate; when the interlayer ions contained both carbonate anions and long-chain quaternary ammonium groups, the corresponding LZH compound was denominated as LZHDC. Interestingly, the LZHDC is transformed into LZHC though a structure and compositional transformation involving an exchange of long-chain quaternary ammonium groups by carbonate anions. We propose a stepwise growth and anion exchange mechanism involving conversion from zinc precursor to LZHDC to LZHC. We demonstrated the utility the LZHs obtained in the process as self-sacrificial templates for formation novel 3D ZnO structures by pyrolysis.
Co-reporter:Bin Huang, Xinxin Ban, Kaiyong Sun, Zhongming Ma, Yanan Mei, Wei Jiang, Baoping Lin, Yueming Sun
Dyes and Pigments 2016 Volume 133() pp:380-386
Publication Date(Web):October 2016
DOI:10.1016/j.dyepig.2016.06.025
•Benzophenone derivatives for delayed fluorescence have been synthesized.•The optical, electrochemical and thermal properties were studied.•The solution-processed non-doped green OLEDs exhibited a high EQE of 4.3%.A series of thermally activated delayed fluorescence materials based on benzophenone derivatives have been synthesized by Ullmann coupling reaction. The optical, electrochemical and thermal properties of benzophenone derivatives were systematically characterized. In comparison with the reported thermally activated delayed fluorescence materials based on benzophenone derivatives, bis-{4-[3,6-bis(3,6-di-tert-butyl-carbazol-9-yl)carbazol]-9-yl-phenyl}-methanone exhibited better solubility and smaller energy gap between the singlet and triplet excited states (0.08 eV). The solution-processed non-doped green OLED using this novel material as an emitter exhibited a low turn-on voltage of 4.5 V, a maximum current efficiency of 9.2 cd A−1, a high external quantum efficiency of 4.3%, and a maximum luminance of 4200 cd m−2.
Co-reporter:Bo Song, Xia Cui, Yuqiao Wang, Lifang Si, Zhaoxia Kou, Wenwen Tian, Chang Yi, and Yueming Sun
Crystal Growth & Design 2016 Volume 16(Issue 9) pp:4877
Publication Date(Web):August 10, 2016
DOI:10.1021/acs.cgd.6b00340
A novel three-dimensional binary structure was successfully synthesized with the assist of soluble long-chain tetraalkylammonium carboxylate zinc salt by hydrothermal treatment. The unique binary structure consists of two different crystal structures in one individual, with the head being a layered basic zinc salt (LBZS) microsphere and the body being a ZnO rod. During the synthesis process, careful concentration and time-controlled experiments were needed to achieve a key intermediate of stable self-assembled LBZS, which was subsequently converted into an LBZS/ZnO binary structure. The presence of the binary structure demonstrates a possible growth mechanism involving stepwise evolution as zinc salt → LBZS → LBZS/ZnO → ZnO, giving an improvement of the understanding of the growth of ZnO in solution. Thus, this study provides the rationality for the existence of the solid-phase transformation as well as the competition relationship between the solid-phase transformation and the dissolution–renucleation process during the transformation process of LBZS to ZnO.
Co-reporter:Kaiyong Sun, Wei Jiang, Xinxin Ban, Bin Huang, Zhaohang Zhang, Muyang Ye and Yueming Sun
RSC Advances 2016 vol. 6(Issue 26) pp:22137-22143
Publication Date(Web):19 Feb 2016
DOI:10.1039/C6RA03281H
Two novel luminescent molecules based on thianthrene-9,9′,10,10′-tetraoxide derivatives, named tCzDSO2 and 3tCzDSO2, have been synthesized and characterized. The compound tCzDSO2 emits intense aggregation-induced emission (AIE) with a high photoluminescence quantum yields (ΦF) of 0.92 at room temperature in the solid state. Simultaneously, by increasing the proportion of carbazole units, 3tCzDSO2 exhibits both AIE and thermally activated delayed fluorescence (TADF) in the solid state with ΦF of 0.19 in air and 0.41 in N2 atmosphere. The two compounds also display a bathochromic effect due to their intramolecular charge transfer (ICT) attribute. The time-dependent DFT predicted the singlet and triplet splitting (ΔEST) values of tCzDSO2 and 3tCzDSO2 to be 0.29 eV and 0.06 eV, respectively. The ΔEST of 3tCzDSO2 is small enough to allow efficient reverse intersystem crossing (RISC), leading to the TADF property at room temperature. As a result, the molecular design provides a simple and effective approach to integrate the features of AIE and TADF into one compound.
Co-reporter:Wei Shen, Zhengjian Qi, Liqiang Yan, Wenwen Tian, Xia Cui, Hongtao Yao and Yueming Sun
RSC Advances 2016 vol. 6(Issue 20) pp:16482-16488
Publication Date(Web):28 Jan 2016
DOI:10.1039/C5RA27189D
We report the synthesis and characterization of two luminescent cyclometalated Ir(III) complexes [Ir(dfppy)2(bpy-DPA)]PF6 (Ir-1) and [Ir(dfppy)2(bpy-BiDPA)]PF6 (Ir-2), where dfppy, bpy-DPA and bpy-BiDPA represent 2-(2,4-difluorophenyl)pyridine, N-([2,2′-bipyridine]-4-yl)-2-(bis(pyridin-2-ylmethyl)amino)acetamide and N,N′-([2,2′-bipyridine]-4,4′-diyl)bis(2-(bis(pyridin-2-ylmethyl)amino)acetamide), respectively. Their photophysical properties and sensing properties towards various metal ions were investigated at room temperature. The two complexes both possessed good photophysical properties, and Ir-2 had quite a high quantum yield (93.83%) and a long lifetime (101.17 μs), which is impressive among Ir(III) complexes. Ir-2 exhibited both high selectivity and sensitivity towards Cu2+ over other metal ions. The Job curve and mass spectra suggested the formation of a 1:2 bonding mode between Ir-2 and Cu2+. The photoluminescence (PL) intensity quenching curve indicated that Ir-2 could enable rapid and reversible detection of Cu2+ with a low detection limit of 0.85 ppb (13 nM). Furthermore, a linear relationship could be observed between the PL lifetime value of Ir-2 and the concentration of Cu2+ ions in the range of 0–8 μM. These results suggested that Ir-2 might have use as not only a promising photoluminescence intensity sensor, but also a promising lifetime sensor for Cu2+ in aqueous solution.
Co-reporter:Wei Shen, Liqiang Yan, Wenwen Tian, Xia Cui, Zhengjian Qi, Yueming Sun
Journal of Luminescence 2016 Volume 177() pp:299-305
Publication Date(Web):September 2016
DOI:10.1016/j.jlumin.2016.04.048
We report the synthesis and characterization of a novel aggregation induced emission (AIE) active cyclometalated Ir(III) complex, namely [Ir(dfppy)2(phen-DPA)]PF6, where dfppy and phen-DPA represent 2-(2,4-difluorophenyl)pyridine and 2-(bis(pyridin-2-ylmethyl)amino)-N-(1,10-phenanthrolin-5-yl)acetamide, respectively. The complex showed remarkable selectivity for copper(II) in aqueous solution over other competitive ions. Furthermore, this sensor showed a rapid and reversible response to copper(II) in aqueous solution with a detection limit of 65 nM.
Co-reporter:Bin Huang, Zhihui Yin, Xinxin Ban, Zhongming Ma, Wei Jiang, Wenwen Tian, Min Yang, Shanghui Ye, Baoping Lin, Yueming Sun
Journal of Luminescence 2016 Volume 172() pp:7-13
Publication Date(Web):April 2016
DOI:10.1016/j.jlumin.2015.11.012
Two bipolar materials based on 9-phenylcarbazole and diphenyl sulfone for nondoped deep blue OLEDs, namely bis-(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles, have been designed and synthesized by Suzuki coupling reactions. Their thermal, photophysical, and electrochemical properties have been systematically investigated. The nondoped devices using 3,6–bis–(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles and 2,7-bis-(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles as the emitters show deep blue emission color with peaks at 424 and 444 nm, and the Commission Internationale de l׳Eclairage (CIE) coordinates of (0.177, 0.117) and (0.160, 0.117), respectively. Furthermore, these materials based devices have high color-purity with small width at half-maximum (FWHM) of 65 and 73 nm, respectively. The results provide a novel approach for the design of deep blue emitter for nondoped OLEDs.
Co-reporter:Xiaotian Wang, Mingyun Zhu, Wanlin Fu, Chengqian Huang, Qing Gu, Tingying Helen Zeng, Yunqian Dai and Yueming Sun
RSC Advances 2016 vol. 6(Issue 52) pp:46218-46225
Publication Date(Web):05 May 2016
DOI:10.1039/C6RA05888D
This work presents an ultrafast and low-cost method to prepare reduced graphene oxide (RGO) by photocatalytic reduction of graphene oxide (GO) sheets with the assistance of dumbbell-like Au nanorods. Au nanoparticles are effectively loaded on the surface of GO sheets by electrostatic interaction and serve as the initiating points for the splitting of GO sheets. The existence of Au nanoparticles tremendously accelerates the process of the reducing reaction as well, in which the reduction completes in 15 min, ascribed to hot electrons generated by the localized surface plasmonic resonance (LSPR) property of Au nanorods. Interestedly, in this process, the function of Au nanorods is not limited to promoting the reduction. The more important merit is that they serve as pore generators which help to cut all of the GO sheets into small pieces. This photocatalytic method of RGO preparation provides a novel strategy in this field and creates various possibilities for future applications.
Co-reporter:Xinxin Ban, Kaiyong Sun, Yueming Sun, Bin Huang, Wei Jiang
Organic Electronics 2016 Volume 33() pp:9-14
Publication Date(Web):June 2016
DOI:10.1016/j.orgel.2016.02.041
•Due to the meta-linking configuration, the triplet energy of the newly designed electron-transporting material is 3.15 eV.•The small ΔEST of the exciplex leads to the successive triplet up-conversion in the transient decay curves.•Due to the high triplet energy, the energy leakage from exciplex-state to the constituting molecule was eliminated.A high triplet energy electron transporting material 1,3,5-tris(diphenylphosphoryl)benzene (TPO) was successfully designed and synthesized to form an efficient exciplex with the commonly used hole transporting molecule tris(4-carbazoyl-9-ylphenyl)amine (TCTA). The singlet-triplet energy difference in this exciplex was only 0.03 eV, which leads to the successive triplet up-conversion and delayed fluorescence. In addition, due to the high triplet energies of TPO and TCTA, the energy leakage from exciplex-state to the constituting molecule was eliminated. By employing this exciplex as host, solution-processed white phosphorescent OLEDs have been realized with a low turn-on voltage of 3 V and a high power efficiency of 20.5 lm W−1. These results indicate that the well-designed exciplex can be used as efficient host material for low-cost solution-processed OLEDs.Due to the high triplet energies of constituting molecules and exciplex, the energy leakages from the excited-state to the components or the dopants were successfully eliminated.
Co-reporter:Yunqian Dai, Yunling Chai, Yibai Sun, Wanlin Fu, Xiaotian Wang, Qing Gu, Tingying Helen Zeng and Yueming Sun
Journal of Materials Chemistry A 2015 vol. 3(Issue 1) pp:125-130
Publication Date(Web):11 Nov 2014
DOI:10.1039/C4TA05869K
Supported metal catalysts are critical to many important chemical reactions, but the weak metal/support interaction is an obstacle to the success of remarkable catalytic performance. This paper reports rational-designed novel Pt supports, consisting of reduced graphene oxide sheets decorated with both Fe2O3 nanorods and N-dopants (denoted as Fe2O3/N-RGO), for Pt photodeposition driven by visible light in a controllable fashion. The 2–3 nm Pt nanocrystals primarily nucleated on rough Fe2O3 nanorods, and interacted strongly with special sites on the Fe2O3 surface using unsaturated vacant orbitals. At the same time, the accelerated photodegradation of undesirable PVP allowed the Pt nanocrystals with clean active sites. The supported Pt showed impressive activity and had a 7-times higher reaction rate constant (11.4 s−1 mg−1) towards 4-nitrophenol reduction, compared with that of free Pt, due to the synergetic effect within the whole Pt/Fe2O3/N-RGO catalysts and the doping of N atoms which acted as new metal-free catalytic centers in N-RGO sheets. We further demonstrated that the ternary catalyst could be easily removed through magnetic separation from the system. This new strategy is extendible to other heterogeneous catalysts with different components.
Co-reporter:Wei Jiang, Xinxin Ban, Muyang Ye, Yueming Sun, Lian Duan and Yong Qiu
Journal of Materials Chemistry A 2015 vol. 3(Issue 2) pp:243-246
Publication Date(Web):24 Nov 2014
DOI:10.1039/C4TC02485K
A novel cross-linkable hole-transporting material (HTM) has been synthesized and characterized. The HTM possesses high triplet energy, excellent film-forming and solvent-resistant abilities, suitable HOMO level and electrochemical stability. Solution processed multilayer blue electrophosphorescent devices using this cross-linked HTM show lower turn-on voltages and doubled efficiencies compared with the corresponding single-layer device.
Co-reporter:Wenwen Tian, Qi Qi, Bo Song, Chang Yi, Wei Jiang, Xia Cui, Wei Shen, Bin Huang and Yueming Sun
Journal of Materials Chemistry A 2015 vol. 3(Issue 5) pp:981-984
Publication Date(Web):22 Dec 2014
DOI:10.1039/C4TC02645D
A novel second-generation bipolar iridium(III) dendrimer featured with diphenylphosphoryl and diphenylamine groups has been designed and synthesized. A maximum current efficiency of 21.6 cd A−1 has been realized, which is among the highest ever reported for single-layer self-host green PhOLEDs.
Co-reporter:Xinxin Ban, Wei Jiang, Kaiyong Sun, Xinyu Xie, Lang Peng, Hongshuang Dong, Yueming Sun, Bin Huang, Lian Duan, and Yong Qiu
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 13) pp:7303
Publication Date(Web):March 18, 2015
DOI:10.1021/acsami.5b00510
Two soluble bipolar host materials (mCP-BPBI and CP-QPBI), comprising different proportions of hole-transporting carbazole and electron-transporting benzimidazole, were synthesized. Their thermal, physical, and electrochemical properties were characterized. The designated bulky star-shaped structures efficiently suppress the direct intramolecular interaction between the donor and acceptor subunits to give high triplet energies. Through computational studies, varying the ratio of hole- and electron-transporting moieties could significantly change the carrier injection/transporting abilities and charge balance properties of the host materials. Indeed, CP-QPBI with more benzimidazole units shows extremely enhanced current density at the same voltage when compared to mCP-BPBI. The operating voltage of solution-processed phosphorescent light-emitting diodes with CP-QPBI as host were dramatically reduced by ∼3 V compared with the similar devices of mCP-BPBI. At the same time, the power efficiencies were improved for 2–2.5 times at the corresponding voltage. Importantly, both blue and green devices maintain their high efficiencies even at brightness up to 1000 cd m–2, which clearly demonstrates that the new strategy applied to improve electron-transporting ability and charge-balance property of the solution-processable host material by tuning the ratio of donor and acceptor unit is profitable.Keywords: bipolar host; high power efficiency; low operating voltage; OLEDs; reorganization energy; solution-process
Co-reporter:Xinxin Ban, Kaiyong Sun, Yueming Sun, Bin Huang, Shanghui Ye, Min Yang, and Wei Jiang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 45) pp:25129
Publication Date(Web):October 26, 2015
DOI:10.1021/acsami.5b06424
Three solution-processable exciplex-type host materials were successfully designed and characterized by equal molar blending hole transporting molecules with a newly synthesized electron transporting material, which possesses high thermal stability and good film-forming ability through a spin-coating technique. The excited-state dynamics and the structure–property relationships were systematically investigated. By gradually deepening the highest occupied molecular orbital (HOMO) level of electron-donating components, the triplet energy of exciplex hosts were increased from 2.64 to 3.10 eV. Low temperature phosphorescence spectra demonstrated that the excessively high triplet energy of exciplex would induce a serious energy leakage from the complex state to the constituting molecule. Furthermore, the low energy electromer state, which only exists under the electroexcitation, was found as another possible channel for energy loss in exciplex-based phosphorescent organic light-emitting diodes (OLEDs). In particular, as quenching of the exciplex-state and the triplet exciton were largely eliminated, solution-processed blue phosphorescence OLEDs using the exciplex-type host achieved an extremely low turn-on voltage of 2.7 eV and record-high power efficiency of 22.5 lm W–1, which were among the highest values in the devices with identical structure.Keywords: blue phosphorescence; exciplex; power efficiency; solution process; turn-on voltage
Co-reporter:Yuqiao Wang, Jing Lu, Jie Yin, Gang Lü, Yingmin Cui, Shasha Wang, Shengyuan Deng, Dan Shan, Hailiang Tao, Yueming Sun
Electrochimica Acta 2015 Volume 185() pp:69-75
Publication Date(Web):10 December 2015
DOI:10.1016/j.electacta.2015.10.103
•The frontier orbitals between 4-tert-butylpyridine and TiO2 are sufficiently overlapped to induce the negative shift of Fermi energy, increasing the open-circuit voltage.•The guanidinium cations can be tightly absorbed on TiO2 surface by electrostatic attraction to form a passivated layer, depressing the recombination rate and improving the short-circuit photocurrent.•The photovoltaic performance might be as a result of a synergistic effect of co-additives due to the competitive effect between volume and electrostatic effect.The co-additives of 4-tert-butylpyridine (TBP) and guanidinium thiocyanate (GuSCN) in electrolytes can prominently affect the photovoltaic behavior of dye-sensitized solar cell (DSSC) due to their advantages fitting with energy levels and charge transfer. Mott-Schottky analysis is used to quantify the TiO2 band edge movement to clarify the change of open-circuit voltage. The corresponding kinetic investigations are carried out using cyclic voltammetry, electrochemical impedance spectroscopy, intensity modulated photocurrent/photovoltage spectroscopy and charge extraction. Theoretically, the density functional theory (DFT) method is performed to explore the details of the adsorption, including the interacting energy, Fermi energy and frontier orbitals properties. The results show that the frontier orbitals between TBP and TiO2 are sufficiently overlapped to induce the negative shift of Fermi energy, increasing the open-circuit voltage. The Gu+ cations can be tightly absorbed on TiO2 surface to by electrostatic attraction form a passivated layer due to the Coulomb attraction, depressing the recombination rate and improving the short-circuit photocurrent. The different proportion of TBP and GuSCN would produce a competitive effect, which would be caused by their volume and electrostatic effect. The photovoltaic performance might be as a result of a synergistic effect of co-additives. DSSC based on the optimal molar ratio (9:1) of TBP and GuSCN achieves its optimized short-circuit current density of 13.74 mA cm−2, open-circuit voltage of 0.74 V, fill factor of 0.70 and overall efficiency of 7.12%.The frontier orbitals between 4-tert-butylpyridine and TiO2 are sufficiently overlapped to induce the negative shift of Fermi energy, increasing the open-circuit voltage. The guanidinium cations can be tightly absorbed on TiO2 surface to form a passivated layer, depressing the recombination rate and improving the short-circuit photocurrent. The photovoltaic performance might be as a result of a synergistic effect of co-additives due to the competitive effect between volume and electrostatic effect.
Co-reporter:Xinxin Ban, Wei Jiang, Zimin Zheng, Junjie Wang, Lin Xia, Jian Zhou, Yueming Sun
Organic Electronics 2015 Volume 24() pp:65-72
Publication Date(Web):September 2015
DOI:10.1016/j.orgel.2015.05.026
•The unique molecular configuration enables the soluble bipolar host high triplet energy (3.0 eV).•The HOMO–LUMO energy gaps gradually decrease with the molecular structure modification.•Once the carrier was well injected, the charge balance property may become important for the device performance.Three bipolar hosts composed of electron-accepting diphenylphosphine oxide and electron-donating carbazole/triphenylamine have been synthesized and characterized. With structural topology modification, the particular physical properties of the materials can be subtly optimized, such as the thermal stability, singlet–triplet energy gap and charge balance ability. Both DFT calculation and experiment results demonstrate that the introduced triphenylamine can effective minimize the HOMO–LUMO energy gap, while the carbazole units can prevent the excited energy loss and keep high triplet energy (ET = 3.0 eV) due to the enhanced molecular rigidity. As a result, solution-processed blue PHOLEDs exhibited a high current efficiency of 25.2 cd A−1 and a power efficiency of 11.5 lm W−1, which implies that the unique molecular modulation is very cost-effective and competitive for the device performance improving.The slight move in one part of the molecule can finely affect the optoelectronic property as a whole, and consequently modulating the thermal stability, singlet–triplet energy difference and charge balance ability.
Co-reporter:Zhaohang Zhang, Wei Jiang, Xinxin Ban, Min Yang, Shanghui Ye, Bin Huang and Yueming Sun
RSC Advances 2015 vol. 5(Issue 38) pp:29708-29717
Publication Date(Web):20 Mar 2015
DOI:10.1039/C5RA00627A
A series of 9,10-diphenyl-anthracene derivatives bearing either benzimidazole or carbazole moieties as substituents were synthesized and characterized as blue emitters for organic light-emitting diodes (OLEDs). Their optical, electrochemical and thermal properties have been investigated, and their molecular structure–property relationships were evaluated. These compounds both exhibited a high glass-transition temperature (Tg ≥ 195 °C) and a high decomposition temperature (Td ≥ 494 °C). The solution processed non-doped device using CAC as a fluorescence emitter showed a maximum luminance efficiency of 1.63 cd A−1, a maximum power efficiency of 0.77 lm W−1 and a maximum external quantum efficiency of 1.53%. By introducing 1,3-bis[4-tert-butylphenyl-1,3,4-oxadiazolyl] phenylene (OXD-7):polyvinylcarbazole (PVK) as host in the emitting layer, the doped deep-blue emitting device of CAC exhibited a turn-on voltage of 4.75 V, a maximum luminance efficiency of 3.03 cd A−1, a maximum power efficiency of 1.64 lm W−1 and a maximum external quantum efficiency of 2.81%. Our results demonstrate a promising approach to well-designed materials for use in deep-blue fluorescence OLED applications.
Co-reporter:Wei Jiang, Peng Cui, Xinxin Ban and Yueming Sun
RSC Advances 2015 vol. 5(Issue 60) pp:48654-48658
Publication Date(Web):27 May 2015
DOI:10.1039/C5RA07730C
A novel material TPA-BPhPO with a photoluminescence quantum yield of 68% and a triplet energy of 2.48 eV has been designed and synthesized. High external quantum efficiencies of 1.41% and 9.3% were achieved in solution-processed blue electrofluorescent and green electrophosphorescent devices, respectively.
Co-reporter:Yunqian Dai, Yibai Sun, Jing Yao, Dandan Ling, Yueming Wang, Huan Long, Xiaotian Wang, Baoping Lin, Tingying Helen Zeng and Yueming Sun
Journal of Materials Chemistry A 2014 vol. 2(Issue 4) pp:1060-1067
Publication Date(Web):30 Oct 2013
DOI:10.1039/C3TA13399K
For TiO2-based photoanodes, the interfacial coupling between TiO2 and conductive materials (e.g., carbon) plays a vital role in determining the electron transfer efficiency and thus photoelectrical performance. In this paper, we describe a facile approach to effectively engineering the interfacial coupling between reduced graphene oxide (RGO) and TiO2 in well-designed one-dimensional (1D) RGO-wrapped TiO2 nanofibers, which act as ultrafast electron transfer bridges when implanted in photoanodes. The 3–5 nm RGO nanoshells were hybridized with TiO2 nanofibers as an electron donor component via d–π electron orbital overlap between C and Ti atoms, by adopting a thermal reduction at 450 °C. Remarkable photoelectric improvement, in terms of high photocurrent density by 2.2-fold and ultralow charge transfer resistance (Rct) by 0.2-fold, is ascribed to the interfacial charge transfer. Completely reduced RGO in RGO/TiO2 nanofibers was not necessary at the expense of their hydrophilicity, as it led to unexpected isolation in the photoanodes. The thermal reduction temperature of RGO/TiO2 nanofibers was found to be critical, and a maximal photocurrent density could be achieved by 2.7-fold at 530 °C. An excess of RGO/TiO2 nanofibers of more than 5 wt% had a degrading effect on the photoelectrical activity, largely due to the light-block effect and isolation in the matrix. This strategy provides new insight for tuning the intrinsic chemical and/or physical properties of well-designed semiconductor nanostructures with promising photoactivities in highly efficient photovoltaic devices.
Co-reporter:Qi Fan, Lixu Lei and Yueming Sun
Nanoscale 2014 vol. 6(Issue 13) pp:7188-7192
Publication Date(Web):05 Mar 2014
DOI:10.1039/C4NR00232F
A facile and efficient synthesis was developed to fabricate a 3D-porous LiNbO3 nanocomposite by microwave-induced auto-combustion. Such a material shows a high reversible capacity, excellent rate performance and stable cycle performance indicating its great potential as a promising anode material for Li-ion batteries.
Co-reporter:Wenwen Tian, Chang Yi, Bo Song, Qi Qi, Wei Jiang, Yingping Zheng, Zhengjian Qi and Yueming Sun
Journal of Materials Chemistry A 2014 vol. 2(Issue 6) pp:1104-1115
Publication Date(Web):11 Nov 2013
DOI:10.1039/C3TC32024C
The fabrication of electroluminescent devices that combine high device performance with simple device configuration remains an attractive challenge due to their low cost and simple fabrication processes. In this paper, a new series of electrophosphorescent small molecule iridium(III) complexes with diphenylamine-based dendrons of good solubility have been designed. The relationships between their dendritic structures and their photophysical, electrochemical, and electrophosphorescent performances have been systematically investigated. With second-generation dendrons, the photoluminescence quantum yields of the neat film of the dendrimers are almost seven times higher than that of their prototype G0 (Ir(LG0)3, LG0 = 1-methyl-2-phenyl-1H-benzimidazole), and three times that of the first-generation dendron G1 (Ir(LG1)3, LG1 = 4-(1-methyl-1H-benzimidazol-2-yl)-N,N-diphenylbenzenamine). High-quality films of the dendrimers G2 (Ir(LG2)3, LG2 = 1-methyl-2-[4-bis[4-(diphenylamino)phenyl]-aminophenyl]-1H-benzimidazole) and G2Cz (Ir(LG2Cz)3, LG2Cz = 1-methyl-2-[4-bis[4-(9-carbazolyl)phenyl]-aminophenyl]-1H-benzimidazole) have been fabricated by spin-coating, producing highly efficient, non-doped phosphorescent organic light-emitting diodes (PhOLEDs). With a device structure of indium tin oxide/poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonic acid)/neat dendrimer/Cs2CO3/Al, maximum luminous efficiencies of 14.02 cd A−1 and 18.35 cd A−1 have been realized, exhibiting ultrahigh luminous efficiency for single-layer self-host green PhOLEDs. The excellent performances are due to the flower bouquet-shaped iridium dendrimers, which may improve the electron injection and result in greater balance between electron and hole fluxes by the exposure of electron-deficient moieties. The molecular design reported here provides a simple and effective approach to balance charge injection/transporting capacities and develops highly efficient non-doped phosphors suitable for low-cost single-layer device technologies.
Co-reporter:Qi Fan, Lixu Lei, Gui Yin and Yueming Sun
Chemical Communications 2014 vol. 50(Issue 18) pp:2370-2373
Publication Date(Web):03 Dec 2013
DOI:10.1039/C3CC48367C
LiNbO3 nanoplates were directly grown on a self-weaving CNT-network, which was then decorated with polypyrrole to form a flexible electrode. This novel nano-structured anode exhibits superior performance, i.e., high rate discharge capacity and excellent cycle performance.
Co-reporter:Qi Fan, Lixu Lei, Xingyu Xu, Gui Yin, Yueming Sun
Journal of Power Sources 2014 Volume 257() pp:65-69
Publication Date(Web):1 July 2014
DOI:10.1016/j.jpowsour.2014.01.044
•FePO4/graphene and LiFePO4/graphene hybrids were synthesized by a simple method.•A simple and environmentally friendly RAAP-induced growth method was used.•FePO4 and LiFePO4 were direct grown on the graphene-assembled scaffolds.•FePO4/graphene hybrids present superior electrochemical properties.•LiFePO4/graphene hybrids present superior electrochemical properties.FePO4/graphene and LiFePO4/graphene hybrids have been synthesized by an eco-friendly RAAP-directed growth method. With this strategy, FePO4 and LiFePO4 particles have been grown on the exfoliated graphene-assembled scaffolds. Both of the hybrids present superior electrochemical properties, i.e., high rate capability combined with good capacity retention upon cycling, indicating the great potential as the cathode materials for Li-ion batteries.
Co-reporter:Qi Fan, Lixu Lei, Gui Yin, Yanfeng Chen, Yueming Sun
Electrochemistry Communications 2014 Volume 38() pp:120-123
Publication Date(Web):January 2014
DOI:10.1016/j.elecom.2013.11.006
•FePO4 nanospheres were directly grown on the graphene-assembled scaffolds.•A simple and environmentally friendly RAAP-induced growth method was used.•Such hybrids present a uniform morphology and high conductivity of 3.2 S cm− 1.•Such hybrids exhibit superior Li-ion and Na-ion storage performance.An environmentally friendly method has been developed for the direct growth of FePO4 nanospheres on graphene nanosheets with uniform morphology and high conductivity of 3.2 S cm− 1. The nanoassembled FePO4/graphene hybrids exhibit superior Li-ion and Na-ion storage performance, e.g. high rate capability and good capacity retention upon cycling.
Co-reporter:Xinxin Ban, Huange Xu, Guolong Yuan, Wei Jiang, Bin Huang, Yueming Sun
Organic Electronics 2014 Volume 15(Issue 7) pp:1678-1686
Publication Date(Web):July 2014
DOI:10.1016/j.orgel.2014.03.035
•A novel high efficient ultra violet emission type material SF-DPSO was successfully synthesized.•The steric and bulky compound SF-DPSO exhibits an excellent solid state photoluminescence quantum yield (ΦPL = 92%).•The new small molecular material functions not only as a good UV-violet emitter, but also as an efficient host material.A high efficient UV–violet emission type material bis[4-(9,9′-spirobifluorene-2-yl)phenyl] sulfone (SF-DPSO) has been synthesized by incorporating electron deficient sulfone and morphologically stable spirobifluorene into one molecule. The steric and bulky compound SF-DPSO exhibits an excellent solid state photoluminescence quantum yield (ΦPL = 92%), high glass transition temperature (Tg = 211 °C) and high triplet energy (ET = 2.85 eV). In addition, the uniform amorphous thin film could be formed by spin-coating from its solution. These promising physical properties of the material made it suitable for using as UV–violet emitter in non-doped device and appropriate host in phosphorescent OLEDs. With SF-DPSO as an emitter, the non-doped solution processed device achieved an efficient UV–violet emission with the EL peak around 400 nm. By using SF-DPSO as a host, solution processed blue and green phosphorescent organic light emitting diodes showed a high luminous efficiency of 13.7 and 30.2 cd A−1, respectively.Graphical abstractA novel sulfone-based solution processable material with excellent solid state photoluminescence quantum yield, high thermal and morphological stability and high triplet energy can serve not only as efficient emitter for UV–violet electrofluorescence, but also as appropriate host for blue and green phosphorescent organic light-emitting devices.
Co-reporter:Chang Yi, Bo Song, Wenwen Tian, Xia Cui, Qi Qi, Wei Jiang, Zhengjian Qi, Yueming Sun
Tetrahedron Letters 2014 Volume 55(Issue 37) pp:5119-5123
Publication Date(Web):10 September 2014
DOI:10.1016/j.tetlet.2014.05.105
A series of novel fluorene derivatives containing –PO(OH)2 (1, 2), –HS (3), and –N+ (CH3)3 (4) were synthesized and only phosphonic-functionalized fluorene derivatives can detect Fe3+ with high selectivity over other metal ions. The fluorescence quenching of 1 and 2 with titration Fe3+ in water–DMF solution fits the Perrin model of static quenching. Spectral analysis showed that Fe3+ bound with fluorene-based chemosensor through the O-atoms at the phosphonic group to form nonfluorescent complexes. The binding ratio was estimated by the Job plot and the trace levels of iron in samples were successfully monitored.
Co-reporter:Yu-Qiao Wang, Xue-Ling Gao, Bo Song, Yun-Liang Gu, Yue-Ming Sun
Chinese Chemical Letters 2014 Volume 25(Issue 4) pp:491-495
Publication Date(Web):April 2014
DOI:10.1016/j.cclet.2014.01.003
The MWCNT–TiO2 hybrid materials were prepared by a simply mixing method and used as a counter electrode (CE) for dye-sensitized solar cells. Compared with the platinum CE, MWCNT–TiO2 CE has the similar redox voltage and current response in the cyclic voltammetry. The electrochemical catalytic activity was characterized by the electrochemical impedance spectroscopy and Tafel curve, including the equivalent circuit, the exchange current density, the limiting diffusion current density, and the diffusion coefficient of triiodide/iodide redox species. The results indicate that the reduction process from triiodide to iodide is determined by the kinetic-controlled and diffusion-limited processes. The device performance is optimal based on the MWCNT–TiO2 (mass ratio of 2:1) CE, such as the open-circuit voltage of 0.72 V, the short-circuit photocurrent density of 15.71 mA/cm2, the fill factor of 0.68, and the photon-to-electron conversion efficiency of 7.69%.The results of the electrochemical impedance spectroscopy and Tafel measurements indicate that the reduction process from triiodide to iodide at the counter electrode surface is determined by the kinetic-controlled and diffusion-limited processes.
Co-reporter:Jinan Tang, Yuanshen Chen, Lei Cong, Baoping Lin, Yueming Sun
Tetrahedron 2014 70(25) pp: 3847-3853
Publication Date(Web):
DOI:10.1016/j.tet.2014.04.060
Co-reporter:Yuqiao Wang, Qin Liu, Qi Qi, Jianjun Ding, Xiaorui Gao, Yuan Zhang, Yueming Sun
Electrochimica Acta 2013 Volume 111() pp:31-40
Publication Date(Web):30 November 2013
DOI:10.1016/j.electacta.2013.08.010
•RGO/Fe3O4 composite was synthesized by a facile one-pot in-situ procedure.•The RGO/Fe3O4-modified GCE was used for electrocatalytic oxidation of NAC.•Kinetic performance and detection limit of oxidation process were investigated by using different electrochemical methods.The magnetite/reduced graphene oxide (Fe3O4/RGO) composite was synthesized by a facile one-pot in-situ method and characterized by transmission electron microscopy, atomic force microscopy, vibrating sample magnetometer, X-ray powder diffraction, surface area and pore size distribution, thermogravimetric analysis, Raman spectroscopy and X-ray photoelectron spectroscopy, respectively. The composite consisted of the RGO substrate with a single-layered Fe3O4 nanoparticle film, which showed the large surface area of 352 m2 g−1 and the saturated magnetization of 26.7 emu g−1. The average diameter and coverage ratio of Fe3O4 were about 8 nm and 50%, respectively. The electrocatalytic oxidation and detection of N-acetylcysteine (NAC) based on composite-modified glassy carbon electrodes (GCE) were investigated by cyclic voltammetry, amperometry, double potential step chronoamperometry and differential pulse voltammetry. Especially, the kinetic performance of oxidation processes were estimated by the Cottrell equation, indicating the diffusion coefficient of 2.06 × 10−5 cm2 s−1 and the catalytic reaction rate constant of 3.47 × 106 cm3 mol−1 s−1. Compared with the kinetic parameters, it was found that the oxidation process included both slow absorption and quick diffusion processes. The detection limit of NAC was 1.11 × 10−5 mol L−1 in the range of 0.10–10.0 mmol L−1.The Fe3O4/RGO composite has been successfully synthesized by a facile one-pot in-situ procedure. With its high surface area and excellent electrocatalytic activity, the electrochemical sensor based on the composite-modified glassy carbon electrodes was fabricated and applied in detecting the process of NAC electrocatalytic oxidation.
Co-reporter:Chang Yi, Wenwen Tian, Bo Song, Yingpin Zheng, Zhengjian Qi, Qi Qi, Yueming Sun
Journal of Luminescence 2013 Volume 141() pp:15-22
Publication Date(Web):September 2013
DOI:10.1016/j.jlumin.2013.03.017
•A novel phosphonic acid-functionalized fluorene derivatives have been synthesized.•BPPDPF and DPFPA show high sensitivity and selectivity for iron (III).•A novel fluorescence method is applied to the determination of iron in tap water.Novel phosphonic acid-functionalized fluorene derivatives 9, 9-bis (3′-phosphonic acid propyl)-2,7-diphenylfluorene and 2,7-diphenylfluorene-9-ylphosphonic acid, synthesized by Suzuki–Miyaura coupling reaction, were evaluated as a chemoselective Fe3+ ion sensor. Through the disappearance of the characteristic sorption peak of PO, POH and the form of new broad band (POFe stretching bands) in FT-IR spectra, it was verified that the Fe3+ ion cause the quenching of their fluorescence emission, due to the Fe3+ ion binding to them via the O-atoms of the phosphonic group. UV–vis analyses also gave evidences by the change of absorption peak of them. A linear relationship that flowed with the Perrin model of static quenching was observed between the relative fluorescence intensity (ln F0/F) of BPPDPF and the concentration of iron(III) in the range of 1–8 μM with a detection limit of 0.02 μM, so was with DPFPA in the range of 1–5 μM with a detection limit of 0.01 μM. Selectivity of them for Fe3+ was demonstrated over other metal ions by photoluminescence analysis in DMF–H2O solution. It showed that the other studied metal ions do not affect the determination of iron. We successfully monitored trace levels of iron (III) in tap water samples.
Co-reporter:Yuqiao Wang, Xia Cui, Yuan Zhang, Xiaorui Gao, Yueming Sun
Journal of Materials Science & Technology 2013 Volume 29(Issue 2) pp:123-127
Publication Date(Web):February 2013
DOI:10.1016/j.jmst.2012.12.019
The uniform cauliflower-like ZnO films were deposited on the conducting substrate by a chemical bath deposition in urea/water solution. The film structure and morphology were characterized by X-ray diffraction, thermo-gravimetric differential thermal analysis, energy dispersive spectroscopy, selected area electron diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy. The average diameter of ZnO nanoparticles and the petal thickness were 25 nm and 8 μm, respectively. Dye-sensitized solar cells based on the cauliflower-like ZnO film electrode showed the short-circuit current density of 6.08 mA/cm2, the open-circuit photovoltage of 0.66 V, the fill factor of 0.55 and the overall conversion efficiency of 2.18%. The equivalent circuit of cells based on the ZnO film electrodes was measured by the electrochemical impedance spectroscopy. Furthermore, the analysis of equivalent circuit provided the relationship between the cell performance and the interfacial resistance, such as the shunt resistance and the series resistance.
Co-reporter:Xiao-Wei Niu;Shou-Nian Ding;Chao-Chao Chen;Bo Song;Hui-Bo Xu;Zheng-Jian Qi;Qi Qi
Journal of Applied Polymer Science 2012 Volume 124( Issue 1) pp:248-256
Publication Date(Web):
DOI:10.1002/app.34099
Abstract
Urea–formaldehyde (UF) resin microcapsules doped with TiO2 nanoparticles were prepared by in situ polymerization, and the properties of the microcapsules, such as the surface morphologies, thermal properties, and chemical elemental composition, were measured by optical microscopy, scanning electron microscopy, thermogravimetric analysis, and energy-dispersive X-ray spectrometer analysis. The effects of the presence of ammonium chloride and its concentration and the concentrations of UF resin prepolymer and TiO2 nanoparticles during the reaction and deposition of UF on the microcapsule surface on the properties of the microcapsules were investigated. Enhanced UF resin microcapsules with more stability and mechanical strength could be obtained under the optimal conditions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Cai Zhao-Sheng;Sun Yue-Ming;Yang Chun-Sheng;Zhu Xue-Mei
Journal of Applied Polymer Science 2012 Volume 125( Issue 2) pp:1146-1151
Publication Date(Web):
DOI:10.1002/app.33910
Abstract
Para-biguanidinyl benzoyl chitosan hydrochloride (p-BGBC) is prepared with chitosan (CTS) and para-biguanidinyl benzoyl chloride, which is synthesized by acidchloride reaction of para-biguanidinyl benzonic acid hydrochloride (p-BGBA), as starting material in the medium consisted of MeSO3H and dimethyl sulfoxide (DMSO). Structure of p-BGBC is characterized by FT-IR, 1H NMR and gel permeation chromatography (GPC), and its antimicrobial activities are evaluated against a Gram-negative bacterium Escherichia coli (E. coli) and a Gram-positive bacterium Staphylococcus aureus (S. aureus). Compared with CTS hydrochloride, p-BGBC has much stronger antimicrobial activities, which increase with the increase of its degree of substitution (DS) of guanidinylation. When the DS of p-BGBC achieves or exceeds 36.8%, its antibacterial activities against the tested bacteria are higher than that of Bromo-Geramium. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Junting Xi;Orawan Wiranwetchayan
Journal of Materials Science: Materials in Electronics 2012 Volume 23( Issue 9) pp:1657-1663
Publication Date(Web):2012 September
DOI:10.1007/s10854-012-0643-7
Single-crystalline TiO2 nanorods (TiO2 NRs) are grown directly on FTO substrates by hydrothermal methods. The diameters and lengths of TiO2 NRs are easily controlled by growth conditions. When used in hybrid solar cells, TiO2 NRs function as the continuous pathway for fast electron transport to charge collecting electrode, demonstrating a high power conversion efficiency (PCE) of 3.21% with 140 nm long TiO2 NRs. The bilayer polymer coating are introduced into 500 nm long TiO2 NRs to reduce the surface roughness, resulting in the improved contact between the polymer blend and silver electrode and an enhanced PCE from 2.70 to 3.07%.
Co-reporter:Haiqing Xu;Ai-Ping Li;Qi Qi;Wei Jiang
Korean Journal of Chemical Engineering 2012 Volume 29( Issue 9) pp:1178-1186
Publication Date(Web):2012 September
DOI:10.1007/s11814-012-0014-3
La and Ru doped Ti/SnO2-Sb electrodes were prepared by thermal decomposition and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It confirmed that the surface of the La and Ru doped Ti/SnO2-Sb electrodes presents a certain microspherical structure formed by aggregates of nanoparticles, which increases the specific area greatly and provides more active sites. The enhanced performance of the La and Ru doped electrodes arose from the increased adsorption capacity of hydroxyl radicals. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed an improvement of the electrochemical capacity for the La and Ru doped Ti/SnO2-Sb electrodes. The electrochemical oxidation performance of the prepared electrode was further studied using phenol as a model pollutant. UV scans revealed that both phenol and its intermediate products are more rapidly decomposed, especially in the early stage of oxidation on the La and Ru doped electrodes. The removals of chemical oxygen demand (COD) were 86.4% and 82.1% on the Ti/SnO2-Sb-La and Ti/SnO2-Sb-Ru electrodes, respectively, which were higher than that on the SnO2-Sb/Ti electrode (60.1%). The doped electrodes are demonstrated to have superior electrochemical oxidation ability for phenol.
Co-reporter:Kuizhong Song;Ju Bao;Yueming Sun;John Z. H. Zhang
Chinese Journal of Chemistry 2011 Volume 29( Issue 7) pp:1307-1311
Publication Date(Web):
DOI:10.1002/cjoc.201180241
Abstract
Developing orally available small molecule inhibitors of HIV-1 fusion has attracted significant interest over many years. Frey had recently reported several synthetic compounds which are experimentally shown to inhibit cell-cell fusion in the low micromolar range. We carried out computational study to help identify possible binding modes by docking these compounds onto the hydrophobic pocket on gp41 and to characterize structures of binding complexes. The detailed gp41-molecule binding interactions and free energies of binding are obtained through molecular dynamics simulation and MM-PBSA calculation. Specific molecular interactions in the gp41-inhibitor complexes are identified. The present computational study complements the corresponding experimental investigation and helps establish a good starting point for further refinement of small molecular gp41 inhibitors.
Co-reporter:Xiao-Wei Niu;Shou-Nian Ding
Journal of Materials Science: Materials in Electronics 2011 Volume 22( Issue 12) pp:1865-1874
Publication Date(Web):2011 December
DOI:10.1007/s10854-011-0374-1
Ce-doped TiO2 hollow yellow pigment particles were synthesized by coupling template-directed method with Pechini sol–gel process. The effects of water content, ethanol/acetonitrile volume ratio and tetrabutyl orthotitanate concentration, on the fabrication of PS@TiO2 composite particles (the key intermediate product) were investigated and the final pigments were characterized in detail by X-ray diffraction, transmission electron microscopy, scanning electron microscope, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection. The results show that the optimal water content and ethanol/acetonitrile volume ratio are 0.09 mol dm−3 and 3:1, respectively, for the construction of neat PS@TiO2 core–shell structure without secondary titania particles, and that the damage of hollow spheres can be avoided by increasing the shell thickness, and that the prepared hollow spheres were well-crystallised with anatase phase TiO2 and cubic CeO2. Owing to the intrinsic yellow color and lower density, the as-prepared hollow pigments can be expected to be used for color electronic paper display.
Co-reporter:Liang Pu, Yueming Sun, Zhibing Zhang
Journal of Molecular Liquids 2010 Volume 154(2–3) pp:124-130
Publication Date(Web):31 July 2010
DOI:10.1016/j.molliq.2010.04.022
In chemical industry, hydrogen bonding (H-bonding) in the dilute aqueous solutions of acetic acid (HAc) always causes a low efficiency in the distillation for separating HAc from the HAc/H2O mixture. This research examined the H-bonding in the side-on rings (SO), one of the favorable structures in the HAc hydrates, by analyzing the energies and the infrared frequencies of different hydrates from quantum chemical calculations. It is found that the OO―H···HW H-bond in a hydroxyl SO ring and the OC═O···HW in a carbonyl SO ring are slightly weaker than the HO―H···OW or OC═O···HW in a head-on ring (HO). The H-bonding is obviously strengthened for either the HO or the SO ring containing water molecules from none to one and two. When more water molecules are involved, the HO and SO rings become correlated and show a lower binding energy. These features indicate that the H-bonding in the SO ring is also favorable and the preferable structures are the combination or correlation of the SO and HO rings. In this case, it is very difficult to isolate HAc from these water-surrounded structures. Therefore, it needs much more effort to separate HAc from the dilute HAc aqueous solutions than from the high concentrated solutions, where the main interactions are those between HAc molecules.
Co-reporter:Zheng-Jian Qi;Bin Wei;Chen Shi;Yan-Fang He;Jing Yu;Xue-Mei Wang;Feng Kang;Biao Jin
Journal of Applied Polymer Science 2010 Volume 116( Issue 3) pp:1392-1399
Publication Date(Web):
DOI:10.1002/app.30506
Abstract
A novel alternating copolymer with 3-alkylthiophene and oxadiazole (or pyridine) units in ordered arrangement was synthesized with vinyl as a bridge for the first time. The synthesis process included four steps: bromomethylation, preparation of the ylide monomer, the formation of 2,4-divinyl-3-alkylthiophene, and Heck alternating copolymerization. The Fourier transform infrared spectroscopy, 1H-NMR, and gel permeation chromatography measurements showed that all of the copolymers had the required structures. The weight-average molecular weights of the copolymers were in the range 5500–15,000 with a relatively low polydispersity index of 1.4–1.7. The solubility of the copolymers in common solvents (e.g., methylene chloride, chloroform, tetrahydrofuran) was excellent. The optical properties and bandgap of the copolymers was compared with corresponding poly(3-alkylthiophene) homopolymers. The photoluminescence quantum efficiency (QE) of the copolymers improved markedly in chloroform. The QEs of poly(2,4-divinyl-3-hexylthiophene-alt-2,5-diphenyl-1,3,4- oxadiazole) and poly(2,4-divinyl-3-octythiophene-alt-2,5-diphenyl-1,3,4-oxadiazole) were 43.2 and 34.2%, respectively, which were about 20 and 21 times higher than those of the homopolymers, respectively. The ionization potential of the copolymers between 5.53 and 6.13 eV was appropriated to poly(3-alkylthiophene)s. The high electron affinity of the copolymers (2.71–2.95 eV) made the electrons inject from the cathode more easily. With excellent solubility, low bandgap energy, high QE, and both electron-transporting and hole-transporting abilities, the proposed copolymers might be excellent polymeric materials for applications in polymer light-emitting diodes, light-emitting electrochemical cells, and polymer solar cells. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Qi Qi;Yongquan Ha;Yueming Sun
Journal of Molecular Modeling 2010 Volume 16( Issue 7) pp:1179-1186
Publication Date(Web):2010 July
DOI:10.1007/s00894-009-0631-x
Using TD-PBE1PBE/6-31G* and TD-B3LYP/6-31G* approaches, we calculated the absorption and emission spectra of 1,8-naphthalmide derivatives in gas-phase. The geometric structures optimized by HF/6-31G* and B3LYP/6-31G* models and the absorption and emission maxima were in good agreement with existed experimental measurements. It was also found that the lowest singlet states corresponded mainly to the electronic transition from the highest occupied orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). Intramolecular charge transfer occurred between substituents and naphthalimic rings. Study also showed that most compounds with low absorption excitation energies had low vertical ionization potentials. Finally, the delocalization electronic energies between substituents and naphthalimic rings of isomers were investigated to obtain further sight into their stability.
Co-reporter:Wei Jiang, Jinan Tang, Qi Qi, Weibing Wu, Yueming Sun, Dawei Fu
Dyes and Pigments 2009 Volume 80(Issue 1) pp:11-16
Publication Date(Web):January 2009
DOI:10.1016/j.dyepig.2008.04.005
Three new naphthalimide derivatives containing an electron-donor moiety (carbazole), 4-carbazolyl-N-methyl-1,8-naphthalimide, 4-carbazolyl-N-cyclohexyl-1,8-naphthalimide and 4-carbazolyl-N-phenyl-1,8-naphthalimide were synthesized and crystal structures confirmed. Crystallographic data revealed that the interplanar angles (θ) of the carbazole and naphthalimide moieties were, respectively, 70.7° and 66.5°. The UV–vis absorption and photoluminescent spectra of the systems in n-hexane, CHCl3, tetrahydrofuran and CH2Cl2 were investigated. The lowest absorption band of the naphthalimide molecular centered at 400–420 nm was assigned to charge-transfer transition with emission at ≈440 nm in n-hexane and at ≈560 nm in CH2Cl2.
Co-reporter:Hai-Bin Zhu, Jian Zhao, Fan Kong, Shao-Hua Gou, Yue-Ming Sun
Journal of Molecular Structure 2009 Volume 928(1–3) pp:95-98
Publication Date(Web):30 June 2009
DOI:10.1016/j.molstruc.2009.03.017
Isostructural zinc (II) and cadmium (II) coordination complexes with 4-pyridin-4-yl-pyrimidine-2-sulfonate have been prepared and structurally determined. Both the complexes exhibit intense fluorescence in the solid state.
Co-reporter:Wei Jiang, Jinan Tang, Qi Qi, Yueming Sun, Hengyun Ye, Dawei Fu
Dyes and Pigments 2009 80(3) pp: 279-286
Publication Date(Web):
DOI:10.1016/j.dyepig.2008.07.009
Co-reporter:Liang Pu;YueMing Sun;ZhiBing Zhang
Science China Chemistry 2009 Volume 52( Issue 12) pp:
Publication Date(Web):2009 December
DOI:10.1007/s11426-009-0288-4
In separation processes, hydrogen bonding has a very significant effect on the efficiency of isolation of acetic acid (HOAc) from HOAc/H2O mixtures. This intermolecular interaction on aggregates composed of a single HOAc molecule and varying numbers of H2O molecules has been examined by using ab initio molecular dynamics simulations (AIMD) and quantum chemical calculations (QCC). Thermodynamic data in aqueous solution were obtained through the self-consistent reaction field calculations and the polarizable continuum model. The aggregation free energy of the aggregates in gas phase as well as in aqueous system shows that the 6-membered ring is the most favorable structure in both states. The relative stability of the ring structures inferred from the thermodynamic properties of the QCC is consistent with the ring distributions of the AIMD simulation. The study shows that in dilute aqueous solution of HOAc the more favorable molecular interaction is the hydrogen bonding between HOAc and H2O molecules, resulting in the separation of acetic acid from the HOAc/H2O mixtures with more difficulty than usual.
Co-reporter:Hualin Wang, Yueming Sun, Zhengjian Qi, Fan Kong, Yongquan Ha, Shougen Yin and Shen Lin
Macromolecules 2008 Volume 41(Issue 10) pp:3537-3542
Publication Date(Web):April 18, 2008
DOI:10.1021/ma702774x
A novel hyperbranched copolymer, poly(2,4,6-tributyloxy-1,3,5- trivinylenephenylene-co-2-methoxy-5-octyloxy-p-phenyelenevinylene) PTBOTV-co-PMOPV, and a linear counterpart poly(2-methoxy-5-octyloxy-p-phenyelenevinylene) (PMOPV) were synthesized by the Gilch polymerization and characterized with UV−vis, FT-IR, 1H NMR and Photoluminescence (PL) spectroscopy. PTBOTV-co-PMOPV showed excellent solubility, good film-formation ability, and high thermal stability. The UV−vis, PL, and electroluminescence (EL) spectra of PTBOTV-co-PMOPV were blue-shifted approximately 9−15 nm on comparison with those of PMOPV. The polymer light-emitting diode (PLED) was fabricated in ITO/PEDOT (50 nm)/polymer (60 nm)/Alq3 (30 nm)/LiF (1 nm)/Al (200 nm) configuration. The PTBOTV-co-PMOPV exhibited the maximum external quantum efficiency (EQE) of 0.26% at 60.7 cd/m2, while the PMOPV device showed the maximum EQE of 0.17% at 88 cd/m2.
Co-reporter:Yingping ZHENG, Shan GE, Xueying ZHOU, Hong CHEN, Shuo HUANG, Shaorong WANG, Yueming SUN
Journal of Rare Earths (December 2012) Volume 30(Issue 12) pp:
Publication Date(Web):1 December 2012
DOI:10.1016/S1002-0721(12)60213-0
In this paper, we reported the fuel cell performance with La0.8Sr0.2MnO3 (LSM)/Ce0.8Sm0.2O1.9 (SDC) composite cathode prepared from LSM powders of different particle sizes via the silk-printing technique. It was found that the change in particle size of LSM nanoparticle from 40 to 90 nm resulted in an increase in the maximum power density from 132 to 228 mW/cm2 at 650 °C with H2 as fuel and O2 as oxidant. And the polarization resistance of the electrode decreased from 2.547 to 1.034 Ω·cm2. Concerning the particle size of electrode materials, a higher activity was anticipated with smaller particles because a large number of TPB or electrode surface sites along with a higher porosity could be developed. However, this study showed that the electrode prepared with particles of larger diameter had fine and uniform microstructure resulting in higher power density and lower overpotential, where homogeneous distribution of particles and pores was beneficial for increasing the electrochemical active area and the electronic conductivity of the electrodes as well as the gas diffusion for the reactants.
Co-reporter:Wei Jiang, Xinxin Ban, Muyang Ye, Yueming Sun, Lian Duan and Yong Qiu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 2) pp:NaN246-246
Publication Date(Web):2014/11/24
DOI:10.1039/C4TC02485K
A novel cross-linkable hole-transporting material (HTM) has been synthesized and characterized. The HTM possesses high triplet energy, excellent film-forming and solvent-resistant abilities, suitable HOMO level and electrochemical stability. Solution processed multilayer blue electrophosphorescent devices using this cross-linked HTM show lower turn-on voltages and doubled efficiencies compared with the corresponding single-layer device.
Co-reporter:Qi Fan, Lixu Lei, Gui Yin and Yueming Sun
Chemical Communications 2014 - vol. 50(Issue 18) pp:NaN2373-2373
Publication Date(Web):2013/12/03
DOI:10.1039/C3CC48367C
LiNbO3 nanoplates were directly grown on a self-weaving CNT-network, which was then decorated with polypyrrole to form a flexible electrode. This novel nano-structured anode exhibits superior performance, i.e., high rate discharge capacity and excellent cycle performance.
Co-reporter:Yunqian Dai, Yunling Chai, Yibai Sun, Wanlin Fu, Xiaotian Wang, Qing Gu, Tingying Helen Zeng and Yueming Sun
Journal of Materials Chemistry A 2015 - vol. 3(Issue 1) pp:NaN130-130
Publication Date(Web):2014/11/11
DOI:10.1039/C4TA05869K
Supported metal catalysts are critical to many important chemical reactions, but the weak metal/support interaction is an obstacle to the success of remarkable catalytic performance. This paper reports rational-designed novel Pt supports, consisting of reduced graphene oxide sheets decorated with both Fe2O3 nanorods and N-dopants (denoted as Fe2O3/N-RGO), for Pt photodeposition driven by visible light in a controllable fashion. The 2–3 nm Pt nanocrystals primarily nucleated on rough Fe2O3 nanorods, and interacted strongly with special sites on the Fe2O3 surface using unsaturated vacant orbitals. At the same time, the accelerated photodegradation of undesirable PVP allowed the Pt nanocrystals with clean active sites. The supported Pt showed impressive activity and had a 7-times higher reaction rate constant (11.4 s−1 mg−1) towards 4-nitrophenol reduction, compared with that of free Pt, due to the synergetic effect within the whole Pt/Fe2O3/N-RGO catalysts and the doping of N atoms which acted as new metal-free catalytic centers in N-RGO sheets. We further demonstrated that the ternary catalyst could be easily removed through magnetic separation from the system. This new strategy is extendible to other heterogeneous catalysts with different components.
Co-reporter:Yunqian Dai, Yibai Sun, Jing Yao, Dandan Ling, Yueming Wang, Huan Long, Xiaotian Wang, Baoping Lin, Tingying Helen Zeng and Yueming Sun
Journal of Materials Chemistry A 2014 - vol. 2(Issue 4) pp:NaN1067-1067
Publication Date(Web):2013/10/30
DOI:10.1039/C3TA13399K
For TiO2-based photoanodes, the interfacial coupling between TiO2 and conductive materials (e.g., carbon) plays a vital role in determining the electron transfer efficiency and thus photoelectrical performance. In this paper, we describe a facile approach to effectively engineering the interfacial coupling between reduced graphene oxide (RGO) and TiO2 in well-designed one-dimensional (1D) RGO-wrapped TiO2 nanofibers, which act as ultrafast electron transfer bridges when implanted in photoanodes. The 3–5 nm RGO nanoshells were hybridized with TiO2 nanofibers as an electron donor component via d–π electron orbital overlap between C and Ti atoms, by adopting a thermal reduction at 450 °C. Remarkable photoelectric improvement, in terms of high photocurrent density by 2.2-fold and ultralow charge transfer resistance (Rct) by 0.2-fold, is ascribed to the interfacial charge transfer. Completely reduced RGO in RGO/TiO2 nanofibers was not necessary at the expense of their hydrophilicity, as it led to unexpected isolation in the photoanodes. The thermal reduction temperature of RGO/TiO2 nanofibers was found to be critical, and a maximal photocurrent density could be achieved by 2.7-fold at 530 °C. An excess of RGO/TiO2 nanofibers of more than 5 wt% had a degrading effect on the photoelectrical activity, largely due to the light-block effect and isolation in the matrix. This strategy provides new insight for tuning the intrinsic chemical and/or physical properties of well-designed semiconductor nanostructures with promising photoactivities in highly efficient photovoltaic devices.
Co-reporter:Wenwen Tian, Chang Yi, Bo Song, Qi Qi, Wei Jiang, Yingping Zheng, Zhengjian Qi and Yueming Sun
Journal of Materials Chemistry A 2014 - vol. 2(Issue 6) pp:NaN1115-1115
Publication Date(Web):2013/11/11
DOI:10.1039/C3TC32024C
The fabrication of electroluminescent devices that combine high device performance with simple device configuration remains an attractive challenge due to their low cost and simple fabrication processes. In this paper, a new series of electrophosphorescent small molecule iridium(III) complexes with diphenylamine-based dendrons of good solubility have been designed. The relationships between their dendritic structures and their photophysical, electrochemical, and electrophosphorescent performances have been systematically investigated. With second-generation dendrons, the photoluminescence quantum yields of the neat film of the dendrimers are almost seven times higher than that of their prototype G0 (Ir(LG0)3, LG0 = 1-methyl-2-phenyl-1H-benzimidazole), and three times that of the first-generation dendron G1 (Ir(LG1)3, LG1 = 4-(1-methyl-1H-benzimidazol-2-yl)-N,N-diphenylbenzenamine). High-quality films of the dendrimers G2 (Ir(LG2)3, LG2 = 1-methyl-2-[4-bis[4-(diphenylamino)phenyl]-aminophenyl]-1H-benzimidazole) and G2Cz (Ir(LG2Cz)3, LG2Cz = 1-methyl-2-[4-bis[4-(9-carbazolyl)phenyl]-aminophenyl]-1H-benzimidazole) have been fabricated by spin-coating, producing highly efficient, non-doped phosphorescent organic light-emitting diodes (PhOLEDs). With a device structure of indium tin oxide/poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonic acid)/neat dendrimer/Cs2CO3/Al, maximum luminous efficiencies of 14.02 cd A−1 and 18.35 cd A−1 have been realized, exhibiting ultrahigh luminous efficiency for single-layer self-host green PhOLEDs. The excellent performances are due to the flower bouquet-shaped iridium dendrimers, which may improve the electron injection and result in greater balance between electron and hole fluxes by the exposure of electron-deficient moieties. The molecular design reported here provides a simple and effective approach to balance charge injection/transporting capacities and develops highly efficient non-doped phosphors suitable for low-cost single-layer device technologies.
Co-reporter:Wenwen Tian, Qi Qi, Bo Song, Chang Yi, Wei Jiang, Xia Cui, Wei Shen, Bin Huang and Yueming Sun
Journal of Materials Chemistry A 2015 - vol. 3(Issue 5) pp:NaN984-984
Publication Date(Web):2014/12/22
DOI:10.1039/C4TC02645D
A novel second-generation bipolar iridium(III) dendrimer featured with diphenylphosphoryl and diphenylamine groups has been designed and synthesized. A maximum current efficiency of 21.6 cd A−1 has been realized, which is among the highest ever reported for single-layer self-host green PhOLEDs.
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