Co-reporter:Chen Chen;Xinqian Zhang;Hanying Li;Hongzheng Chen
Advanced Optical Materials 2017 Volume 5(Issue 2) pp:
Publication Date(Web):2017/01/01
DOI:10.1002/adom.201600539
An ultrasensitive visible-light transistor is fabricated by applying one-step solution-processed 2D perovskite (C6H5C2H4NH3)2SnI4 film with high crystallinity as the channel layer. The phototransistor shows high photoresponsivity over 104 A W–1 to very week visible-light signals because of the inorganic charge-carrying sheets extending in the direction of carrier transport in the field-effect transistor.
Co-reporter:Shida Yang, Wenqing Liu, Lijian Zuo, Xinqian Zhang, Tao Ye, Jiehuan Chen, Chang-Zhi Li, Gang Wu and Hongzheng Chen
Journal of Materials Chemistry A 2016 vol. 4(Issue 24) pp:9430-9436
Publication Date(Web):17 May 2016
DOI:10.1039/C6TA02999J
Thiocyanate ammonium (NH4SCN) is introduced into the fabrication of formamidinium lead triiodide (FAPbI3) films through one-step spin-coating. The promoted formation of black trigonal phase α-FAPbI3 with better crystallinity has been observed after the addition of NH4SCN, together with the supression of the formation of yellow hexagonal phase δ-FAPbI3. Planar perovskite solar cells (PVSCs) based on NH4SCN-assisted formed α-FAPbI3 films with high quality present a highest power conversion efficiency of 11.44% when 30 mol% NH4SCN is applied. Notably, the addition of NH4SCN is found to enhance the moisture stability of the perovskite. As a result, the planar PVSCs with 30 mol% NH4SCN additive show improved stability under ambient conditions (RH: 30–40%) over those based on pristine FAPbI3. NH4SCN simultaneously enhances the efficiency and moisture stability of FAPbI3 based PVSCs through a single one-step solution method, facilitating their commercial fabrication and application.
Co-reporter:Bing Guo, Gang Wu, Hong-Zheng Chen, Mang Wang
Organic Electronics 2016 Volume 29() pp:13-21
Publication Date(Web):February 2016
DOI:10.1016/j.orgel.2015.11.018
•Devices with structure of ITO/PEDOT:PSS/TmPyPB/Py-NaTaO3/Al were fabricated.•Device presented selective sensitivity to wavelength shorter than 317 nm UV light.•The device showed ultraviolet signal-to-noise ratio of about 3 orders of magnitude.Wide bandgap NaTaO3 nanocrystals (NaTaO3 NCs) were synthesized by a two-step hydrothermal method. The hybrid film based on the pyridine modified NaTaO3 NCs and 1, 3, 5-tri(m-pyrid-3-yl-phenyl) benzene (TmPyPB) was prepared by solution processing at room temperature. Photodetector based on the hybrid film presented selective sensitivity to UV signals with wavelength shorter than 317 nm because the bandgap wider than 4.0 eV. Under 5 mW/cm2 280 nm illumination through the semi-transparent Al cathode, a high ultraviolet signal-to-noise ratio of 3 orders of magnitude with response time about 200–300 ms can be achieved for the device in the case of −3 V bias.
Co-reporter:Weiwei Tu, Tang Liu, Zhongqiang Zhang, Gang Wu, Hongzheng Chen, Mang Wang
Synthetic Metals 2016 Volume 219() pp:20-25
Publication Date(Web):September 2016
DOI:10.1016/j.synthmet.2016.05.004
•Two fluorene-based derivatives, TPF and DFPPO, with wide bandgap were synthesized.•Diphenylphosphine oxide group helps to increase the electron mobility of DFPPO.•TPF and DFPPO can be applied as the acceptor in the active layer of the UV sensor.Two fluorene derivatives, 2-(1,1′:3′,1″-triphenyl-5′-yl)-9,9-diphenyl-9H-fluorene (TPF) and (9,9-diphenyl-9H-fluoren-2-yl)diphenylphosphine oxide (DFPPO) with wide bandgap and good thermal stability were synthesized. The electron mobility of DFPPO is 5 times higher than that of TPF because of the introduction of the electron-withdrawing diphenylphosphine oxide group. The planar heterojunction organic ultraviolet photodetectors (UVDs) were fabricated by applying TPF or DFPPO as electron acceptor, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as donor. The UVDs with structure of ITO/PEDOT:PSS/C8-BTBT/DFPPO/LiF/Al presented higher ultraviolet response compared to the TPF based counterpart. Corresponding dark to light current ratio and higher sensitivity is about 179 and 0.69 mA/W under illumination of 1 mW/cm2 365 nm UV light and bias of −0.5 V.
Co-reporter:Xinqian Zhang;Zhuowei Gu;Bing Guo;Wenqing Liu;Shida Yang
Nano Research 2016 Volume 9( Issue 10) pp:2921-2930
Publication Date(Web):2016 October
DOI:10.1007/s12274-016-1177-8
We systematically investigated the development of film morphology and crystallinity of methyl-ammonium bismuth (III) iodide (MA3Bi2I9) through onestep spin-coating on TiO2-deposited indium tin oxide (ITO)/glass. The precursor solution concentration and substrate structure have been demonstrated to be critically important in the active-layer evolution of the MA3Bi2I9-based solar cell. This work successfully improved the cell efficiency to 0.42% (average: 0.38%) with the mesoscopic architecture of ITO/compact-TiO2/mesoscopic-TiO2 (meso-TiO2)/MA3Bi2I9/2,2′,7,7′-tetrakis(N,N-di-4-methoxyphenylamino)-9,9′spiro-bifluorene (spiro-MeOTAD)/MoO3/Ag under a precursor concentration of 0.45 M, which provided the probability of further improving the efficiency of the Bi3+-based lead-free organic–inorganic hybrid solar cells.
Co-reporter:Bing Guo, Gang Wu, Hongzheng Chen and Mang Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 36) pp:9346-9352
Publication Date(Web):10 Aug 2015
DOI:10.1039/C5TC02334C
A convenient two-step hydrothermal method was developed to synthesize water dispersible NaTaO3 nanoparticles. The growth of the NaTaO3 nanoparticles was retarded with the aid of a water soluble complex agent in the first step, such as citric acid, bicine, triacetin, and EDTA 2Na, which formed complexes with Ta5+. The sizes of the NaTaO3 nanoparticles, ranging from 5 nm to 30 nm, could be tuned by adjusting the reaction time as well as the complexing agent. An ultraviolet photodetector was fabricated with the solution processed NaTaO3 film as the active layer, which presented a sensitive response to 280 nm deep UV illumination with a light to dark current ratio of about 160 and a response time of about 50 ms.
Co-reporter:Gang Wu;Chen Chen;Shuang Liu;Congcheng Fan;Hanying Li ;Hongzheng Chen
Advanced Electronic Materials 2015 Volume 1( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/aelm.201500136
Visible-light transparent 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) single crystal ribbons prepared by low-cost solution process are applied as the channel layer of the UV active field-effect transistor. The device exhibits ultrahigh response to visible-blind and deep UV signals because of the good charge transport ability of the C8-BTBT single-crystals. In the case of very weak 365 nm UV lamination (0.2 mW cm−2), the photo to dark current ratio (P) and photoresponsivity (R) reach to 3.0 × 104 and 1200 A W−1 at Vg = −23 V, Vds = −30 V. When 1 mW cm−2 280 nm deep UV light is applied, the P and R value is 8300 and 44 A W−1, respectively. The result is the highest record in the organic UV photodetectors ever reported. This work offers the possibility of fabricating a high-performance, low-energy exhaust UV sensor free of visible-light interference or UV controlled memory device, and opens a practical avenue for the realization of sensitive detection of deep UV signals.
Co-reporter:Chang-Bo Wu, Gang Wu, Xi Yang, Yu-Jing Liu, Chen-Xi Gao, Qi-Hua Ji, Mang Wang, Hong-Zheng Chen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 457() pp:487-494
Publication Date(Web):5 September 2014
DOI:10.1016/j.colsurfa.2014.06.018
•Mannitol@Silica capsules with thick shell were prepared from the W/O emulsion.•Diffusion of APTS and TEOS across the interface controlled the growth of the shell.•Irreversible phase change over 100 °C shows latent heat of 147.4 J/g.Mannitol@Silica core–shell capsules were prepared from W/O emulsion by adding silicon precursor into the oil-continuous phase to form silica shell through interfacial polymerization reaction. The bicomponent mixture of tetraethoxysilane (TEOS) and 3-aminopropyl triethoxysilane (APTS) was used as silicon precursor to form relatively thick silica shell. The reaction was triggered by the penetration of APTS from oil-continuous phase into the aqueous phase and the silica shell formed as both TEOS and APTS hydrolyzed and polymerized after diffusing through the W/O interface. The growth of the shell layer was believed to be an outside-in mode. The mannitol crystal was well sealed inside the silica capsule under an optimized condition and the leakage was successfully avoided. The Mannitol@Silica core–shell capsules own irreversible phase change character in the range of 142.1–166.2 °C with latent heat of 147.4 J/g.
Co-reporter:Peipei Yin, Gang Wu, Wenlong Qin, Xiaoqiang Chen, Mang Wang and Hongzheng Chen
Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:843-849
Publication Date(Web):29 Nov 2012
DOI:10.1039/C2TC00344A
Chromatic organic pigment–SiO2 composite particles with six different colors (CYM and RGB) were prepared by a modified sol–gel method. With the aid of a cationic polyelectrolyte, poly(diallyldimethylammoniumchloride), amorphous silica was coated onto the surface of organic pigments which was revealed by the variation of the zeta potential and average particle size, together with TEM images and EDX and XPS results. Because of the fine scattering properties of silica to visible light, the intensity of the reflectance peak increased significantly, which makes the composite particles more vivid than the organic pigments. The chromatic electrophoretic suspension was prepared by mixing Span 85 and the composite particles anchored with a self-made block copolymer PLMA-b-PDMAEMA in tetrachloroethylene. All the colored ink particles have similar zeta potentials and mobility of about 30 mV and 4–5 × 10−10 m2 V−1 s−1, respectively. White/color (CYM and RGB) dual-particle electronic ink containing PLMA-b-PDMAEMA treated pigment–SiO2 composite particles and TiO2 grafted with a polymer present excellent performance and quick response under an applied DC field of 0.15 V μm−1.
Co-reporter:Jing-Lin Zhang, Gang Wu, Hong-Zheng Chen, Mang Wang
Organic Electronics 2013 Volume 14(Issue 1) pp:255-259
Publication Date(Web):January 2013
DOI:10.1016/j.orgel.2012.11.011
A triarylamine-containing fluorene derivative (FP) with wide bandgap and excellent thermal stability was synthesized and used as electron donor to construct planar heterojunction organic ultraviolet sensor (UVS), while bis(4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl)diphenylsilane (NSN) was used as electron acceptor. The UVS ITO/PEDOT:PSS/FP/NSN/LiF/Al showed sensitive visible-blind response to UV illumination from both ITO and cathode sides. When no bias applied, the peak responsivity to UV light through ITO and cathode side was 47 and 33 mA/W, respectively. To the irradiation from the semitransparent Al side, the most sensitive response range covers the UVB region. Under a bias of −4 V, the peak responsivity at 300 nm reaches 473 mA/W.Graphical abstractHighlights► UVB sensitive triarylamine-containing fluorine derivative (FP) was synthesized. ► Organic visible-blind UVB sensor with PHJ structure was fabricated. ► The highest responsivity under a bias of −4 V, 473 mA/W, is located at 300 nm.
Co-reporter:Wenlong Qin;Peipei Yin ;Hongzheng Chen
Journal of Applied Polymer Science 2013 Volume 130( Issue 1) pp:645-653
Publication Date(Web):
DOI:10.1002/app.39187
Abstract
RGB tricolor organic pigments were in situ modified by stearyl methacrylate-2-(dimethylamino)ethyl methacrylate-styrene random copolymer [P(SMA-DMA-St)] through solution polymerization. The modified particles were charged in tetrachloroethylene (TCE) with the aid of suitable charge control agent. The structure and electrophoretic property of ink particles were characterized by FTIR, TEM, PALS, et al. P(SMA-DMA-St) modification decreased the particles size and enhanced the suspending stability of the pigments in tetrachloroethylene due to the repulsive forces among the treated pigment particles resulting from the extending polyacrylate chain in the media. Partial crosslinking the P(SMA-DMA-St) on the pigment surface with ethylene glycol dimethacrylate (EGDMA) helped to increase the Zeta potential and electrophoresis mobility of RGB electrophoretic particles. The maximum values of the Zeta potential for red, green, and blue electrophoretic particles reached −36.2, −57.7, and −42.7 mV, respectively. The obtained RGB electrophoretic particles could be applied in the color/white dual-particle electronic ink together with charged TiO2 to show vivid color and white images under a DC electric field. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Sheng Liu, Gang Wu, Hong-Zheng Chen, Mang Wang
Synthetic Metals 2012 Volume 162(1–2) pp:89-94
Publication Date(Web):February 2012
DOI:10.1016/j.synthmet.2011.11.016
In order to prepare metal-oxide-pigment based electrophoretic particles with good suspension stability in the low dielectric medium for electrophoretic display application, ferroferric oxide/silicon oxide (Fe3O4/SiO2) composite particles were prepared via in situ sol–gel method. The transmission electron microscopy (TEM)/scanning electron microscope (SEM) images present the multi core–shell morphology for the Fe3O4/SiO2 particles and the average particle size is 250–350 nm. It was found that the Fe3O4/SiO2 composite particles own lower density than that of Fe3O4 because of SiO2 encapsulation and can suspend stably in tetrachloroethylene after OLOA treatment. Zeta potential and electrophoretic mobility of the OLOA treated Fe3O4/SiO2 composite particles in tetrachloroethylene were measured to be 24.2 mV and 3.80 × 10−10 m2/V s, respectively. The dual-particles electrophoretic dispersion containing OLOA treated Fe3O4/SiO2 composite particles and TiO2 grafted with polymer can show white/black image under low DC field.Graphical abstractHighlights► Multi core–shell Fe3O4/SiO2 particles were prepared for EPID application. ► SiO2 encapsulation eases the surface modification of nano Fe3O4. ► Oppositely charged electrophoretic particles can stably coexist in suspension. ► The prototype device driven in low DC field can present high black/white contrast.
Co-reporter:Jing-Lin Zhang, Ya-Xiong Nan, Hai-Guo Li, Wei-Ming Qiu, Xi Yang, Gang Wu, Hong-Zheng Chen, Mang Wang
Sensors and Actuators B: Chemical 2012 Volume 162(Issue 1) pp:321-326
Publication Date(Web):20 February 2012
DOI:10.1016/j.snb.2011.12.088
A triphenylbenzene-containing carbazole derivative (PCP) with wide bandgap, good hole mobility, and excellent thermal stability was synthesized and used as electron donor to construct planar heterojunction organic ultraviolet sensors (UVSs), while bis(4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl)diphenylsilane (NSN) was used as electron acceptor. The UVS ITO/PEDOT:PSS/PCP/NSN/LiF/Al/Ag showed good responses to illumination from both ITO and cathode sides. When a semitransparent cathode was applied, the response region could be further extended to deep-ultraviolet (DUV) region. When the semitransparent Al (9 nm)/Ag (30 nm) cathode was replaced by Al (13 nm), the blue-shift of the response spectra of the UVS could be found. It was especially interesting that the cutoff of response could be changed by using different kind of cathodes. This study may provide a useful guideline to achieve low-cost organic deep-ultraviolet sensors (DUVSs) with tunable spectral response.
Co-reporter:Hai-guo Li, Gang Wu, Hong-Zheng Chen, Mang Wang
Organic Electronics 2011 Volume 12(Issue 1) pp:70-77
Publication Date(Web):January 2011
DOI:10.1016/j.orgel.2010.10.004
A silane-containing triazine derivative (NSN) with ultrawide bandgap and excellent thermal stability was used as electron acceptor for organic ultraviolet photodetectors. Poly (9,9-dihexylfluorene-2,7-diyl) (PFH), 4,4′,4′′-tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), 2,7-bis(3′,5′-diphenylphenyl)-9,9-diphenylfluorene (PFP) and poly(N-vinylcarbazole) (PVK) were applied as electron donors and respectively combined with NSN to construct planar heterojunction devices: indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/donor/NSN/LiF/Al. Under illumination through the ITO electrode, though all the devices exhibit near-ultraviolet (NUV) response, the cutoff wavelength can be well tuned by selecting donors with different bandgaps. If a semitransparent Al cathode is applied for the incidence of light, the response region can be further extended to deep-ultraviolet (DUV) region. Particularly for PFP/NSN and PVK/NSN based devices, quasi-solar-blind response can be realized by combining home-made NUV-blocking organic filters. As a result, the devices are capable of NUV and DUV-selective response for radiation, respectively from ITO and Al sides. The study shown here may provide a useful guideline to achieve low-cost organic detectors with spectral selective response.
Co-reporter:Pei-pei Yin, Gang Wu, Hong-zheng Chen, Mang Wang
Synthetic Metals 2011 Volume 161(15–16) pp:1456-1462
Publication Date(Web):August 2011
DOI:10.1016/j.synthmet.2011.03.029
To prepare black electrophoretic particles with good suspension stability in the low dielectric medium for electrophoretic display application, four kinds of carbon black (CB)/acrylic copolymer hybrid particles, CB/poly(2-hydroxyethyl acrylate-co-lauryl methacrylate) (P(HEA–LMA)), CB/poly(2-hydroxyethyl acrylate-co-2-ethylhexyl acrylate) (P(HEA–EHA)), CB/poly(2-(dimethylamino)ethyl methacrylate-co-2-ethylhexyl acrylate) (P(DMA–EHA)) and CB/poly(2-(dimethylamino)ethyl methacrylate-co-lauryl methacrylate) (P(DMA–LMA)), were prepared via polar bonding, the interaction between the carboxyl groups on the surface of CB and the hydroxyl or amino group in copolymers. Structure, morphology as well as electrophoretic properties of the particles were examined. The particle size of the P(HEA–EHA) and P(DMA–EHA) treated CB increases with increasing the storage time. While the particle size of the P(HEA–LMA) and P(DMA–LMA) treated CB is time independent, which can be attributed to the better extension of P(LMA) segments in tetrachloroethylene than P(EHA) and the resulting more effective steric effect. When the feed ratio of DMA/LMA was 3:5 by volume, the maximum values of the electrophoretic mobility and Zeta potential reach 5.44 × 10−10 m2 V−1 s−1 and 32.5 mV, respectively. The P(DMA–LMA) anchored CB particles can be applied in the dual-particle electrophoretic dispersion together with negative charged TiO2 to show black and white images.Graphical abstractHighlights► Carbon black/acrylic copolymer hybrid particles were prepared for electrophoretic display application. ► Acrylic copolymer can be anchored stably on CB surface by ultrasonication. ► Treated CB can suspend stably in tetrachloroethylene with the aid of acrylic copolymer with proper chain structure, e.g. P(HEA–LMA) and P(DMA–LMA). ► The CB/P(DMA–LMA) hybrid particles can be applied in the dual particle electrophoretic system.
Co-reporter:RunYing Dai;HongZheng Chen
Science China Chemistry 2011 Volume 54( Issue 2) pp:385-391
Publication Date(Web):2011 February
DOI:10.1007/s11426-010-4203-9
The components and their concentration ratio of surfactant mixture in aqueous solution of gelatin and sodium carboxymethylcellulose (NaCMC) are very important during the preparation of stable microcapsules for electrophoretic display. In this work, hydrocarbon/fluorocarbon composite surfactant was introduced for the first time into the capsule wall to improve the chemical resistance and barrier property of the microcapsules. By investigating surface tension and zeta potential of NaCMC with the mixture of sodium dodecyl sulfate (SDS)/perfluoro-nonene oxy benzene sulfonate (OBS), we found that both the presence of hydrophobic interaction and the hydrogen bonding between NaCMC and SDS/OBS enhanced the adsorption of NaCMC at the oil/water interface and thus facilitated the formation of capsule wall. The morphology, particle size, surface free energy and thermal stability of the obtained microcapsules were characterized. The results showed that optically transparent microcapsules with uniform size, smooth surface and compact wall can be obtained by adjusting the pH value of the reaction system and the concentration ratio of SDS/OBS. Based on the prepared microcapsules, a matrix display prototype operated at 9 V direct current in static driven mode was fabricated.
Co-reporter:Yangang Han ; Congcheng Fan ; Gang Wu ; Hong-Zheng Chen ;Mang Wang
The Journal of Physical Chemistry C 2011 Volume 115(Issue 27) pp:13438-13445
Publication Date(Web):June 9, 2011
DOI:10.1021/jp201413m
A highly ordered, vertically oriented TiO2 nanorod array is successfully synthesized on a transparent conductive substrate with a facile, free-template, and low-temperature solution method and applied in the fabrication of a hybrid ultraviolet photodetector with polyfluorene. With TiCl4 treatment, the device exhibits high UV-sensitive photoductivity and fast response time. A maximum response of 33.2 mA/W at 395 nm is reached under zero bias, which provides a novel route to fabricate a low-cost photodetector with large area.
Co-reporter:Runying Dai;Hongzheng Chen
Colloid and Polymer Science 2011 Volume 289( Issue 4) pp:401-407
Publication Date(Web):2011 February
DOI:10.1007/s00396-011-2375-2
The performance of electrophoretic displays is strongly dependent on the stability of the electrophoretic suspension in the device. In this manuscript, to obtain the stable electrophoretic suspension, the titanium dioxide grafted with poly [N-(p-vinyl benzyl) phthalimide] (TiO2-g-PVBP) composite particles were prepared via radical polymerization. The obtained TiO2-g-PVBP composite particles were fully characterized. The results showed that PVBP was grafted onto TiO2 surface by chemical bonding. The composite particles with the effective diameter of 300 nm can monodisperse stably in tetrachloroethylene due to the long-chain polymer PVBP, which can provide each TiO2 particle with steric stabilization. The zeta potential and electrophoretic mobility of the composite particles were 30.3 mV and 4.69 × 10−6 cm2/Vs, respectively, without charge control agent. With the stable electrophoretic suspension containing the prepared composite particles, the matrix electrophoretic display prototype with good performance operated at 9 V was demonstrated.
Co-reporter:Hai-guo Li, Gang Wu, Min-min Shi, Hong-Zheng Chen, Mang Wang
Synthetic Metals 2010 Volume 160(15–16) pp:1648-1653
Publication Date(Web):August 2010
DOI:10.1016/j.synthmet.2010.05.035
Two new solution processable organic molecules based on carbazole and triphenylamine (TPA) substituted fluorene were synthesized by Suzuki coupling reaction. The bandgap of the molecules can be controlled by the 3,6-linkage of the carbazole. The propeller-shaped TPA moieties endow the molecules with good thermal stability and perfect solution processability. Smooth films of both molecules could be readily obtained by spin-coating and n-type ZnO nanoparticles were further incorporated to construct bulk-heterojunction. Under the excitation of 1 mW/cm2 ultraviolet light at 365 nm, devices with those hybrid films as active layers show a relative quick response with photo-to-dark current ratio of about three orders of magnitude. The current decay time (decay to 1% of the value before removing of the light) is less than 200 ms. Moreover, the spectral response of the devices covers 300–400 nm and can be well tuned by the conjugation length of the organic molecules. Those results indicate that the synthesized molecules might be candidates for solution processable low cost UV photodetectors.
Co-reporter:Runying Dai, Gang Wu, Weigang Li, Qiang Zhou, Xihua Li, Hongzheng Chen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 362(1–3) pp:84-89
Publication Date(Web):5 June 2010
DOI:10.1016/j.colsurfa.2010.03.041
We have described the microcapsules containing electrophoretic fluid as core material, prepared from gelatin, sodium carboxymethylcellulose (NaCMC) and dioctyl sulfosuccinate sodium (DSS) by complex coacervation method. The gelatin/NaCMC/DSS microcapsules are characterized by optical microscopy (OM), scanning electron microscopy (SEM), particle size analysis and thermogravimetric analysis (TGA). It is found that DSS plays an important role in the formation of the microcapsule wall and the concentration of DSS deeply affects the yield of microcapsules by enhancing the interaction between gelatin and NaCMC. The microcapsules prepared with DSS content of 0.6 mM show compact capsule wall which endows the capsules with good barrier property and high thermal stability. These microcapsules are applied successfully to prepare a 4-in. clock display panel controlled by single-chip microprocessor (SCM) operated at a low direct current (DC) voltage of 3 V, demonstrating that these microcapsules are potential for the applications in the area of electrophoretic displays.
Co-reporter:Yangang Han, Gang Wu, Mang Wang, Hongzheng Chen
Polymer 2010 Volume 51(Issue 16) pp:3736-3743
Publication Date(Web):22 July 2010
DOI:10.1016/j.polymer.2010.05.057
Monodispersed ligand-capped TiO2 nanocrystals are synthesized by a low temperature solvothermal method using oleic acid (OA) as the capping agent. The single layer hybrid films based on the OA-capped TiO2 nanocrystals and poly(9,9-dihexylfluorene) (PFH) are prepared by solution processing at room temperature and characterized by atomic force microscopy, UV–vis absorption and photoluminescence spectra. The hybrid film is applied in the fabrication of nanostructured UV-A photodetector (320–420 nm) by sandwiching it between two electrodes to form bulk heterojunction. The high ultraviolet signal-to-noise ratio of 3 orders of magnitude with short response time less than 200 ms can be achieved for the device. Furthermore, the device shows drastic changes in current under a wide range of UV irradiation with a linear relationship between them. The thermal behavior of the device is also discussed. The high photosensitivity in the UV-A range and the low-cost endow them with potential for environmental and biological uses.
Co-reporter:Weigang Li, Gang Wu, Hongzheng Chen, Mang Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 333(1–3) pp:133-137
Publication Date(Web):5 February 2009
DOI:10.1016/j.colsurfa.2008.09.046
Stable, elastic and optical transparent microcapsules containing tetrachloroethylene as core material were prepared from gelatin, sodium dodecyl sulfate (SDS) and sodium carboxymethylcellulose (NaCMC) by complex coacervation method for electrophoretic display. Microcapsules were characterized by scanning electron microscopy, optical microscopy, and thermogravimetric analysis. It is suggested that SDS plays an important role during the process of microencapsulation, i.e. the existence of SDS increases the interaction between gelatin and NaCMC and facilitates the progress of complex coacervation. Because of the compact structure of the capsule wall, the microcapsules represent high thermal stability and good barrier property, both of which prevent core materials from penetrating outside the capsules.
Co-reporter:Xiao-wei Pan;Mang Wang
Journal of Zhejiang University-SCIENCE A 2009 Volume 10( Issue 5) pp:710-715
Publication Date(Web):2009 May
DOI:10.1631/jzus.A0820736
We report that the ultraviolet (UV) light induced photochromic behavior of layered organic-inorganic perovskite material of (C4H9NH3)2CuCl4, changed from yellow to brown after irradiation with UV light (10 mW/cm2) and partially recovered through storage in the dark. (C4H9NH3)2CuCl4 exhibited two distinct absorption bands centered at 286 nm (band I) and 384 nm (band II), which were attributed to the photo-induced exciton formed in 2D inorganic layers sandwiched by organic layers. The blue shift of band I from 287 to 269 nm as well as the decrease of the intensity of band I and band II could be found when samples were irradiated under UV light for different length of time. The simultaneous weakening of the intensity of the N-H⋯Cl hydrogen bond as well as the vibration of the long Cu-Cl bond in the distorted CuCl64− octahedron could be detected from the Fourier transform infrared (FTIR) spectra, which resulted the change of charge distribution of the dissymmetric Cl-Cu⋯Cl bond and the resulting photochromic behavior.
Co-reporter:Bing Guo, Gang Wu, Hongzheng Chen and Mang Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 36) pp:NaN9352-9352
Publication Date(Web):2015/08/10
DOI:10.1039/C5TC02334C
A convenient two-step hydrothermal method was developed to synthesize water dispersible NaTaO3 nanoparticles. The growth of the NaTaO3 nanoparticles was retarded with the aid of a water soluble complex agent in the first step, such as citric acid, bicine, triacetin, and EDTA 2Na, which formed complexes with Ta5+. The sizes of the NaTaO3 nanoparticles, ranging from 5 nm to 30 nm, could be tuned by adjusting the reaction time as well as the complexing agent. An ultraviolet photodetector was fabricated with the solution processed NaTaO3 film as the active layer, which presented a sensitive response to 280 nm deep UV illumination with a light to dark current ratio of about 160 and a response time of about 50 ms.
Co-reporter:Shida Yang, Wenqing Liu, Lijian Zuo, Xinqian Zhang, Tao Ye, Jiehuan Chen, Chang-Zhi Li, Gang Wu and Hongzheng Chen
Journal of Materials Chemistry A 2016 - vol. 4(Issue 24) pp:NaN9436-9436
Publication Date(Web):2016/05/17
DOI:10.1039/C6TA02999J
Thiocyanate ammonium (NH4SCN) is introduced into the fabrication of formamidinium lead triiodide (FAPbI3) films through one-step spin-coating. The promoted formation of black trigonal phase α-FAPbI3 with better crystallinity has been observed after the addition of NH4SCN, together with the supression of the formation of yellow hexagonal phase δ-FAPbI3. Planar perovskite solar cells (PVSCs) based on NH4SCN-assisted formed α-FAPbI3 films with high quality present a highest power conversion efficiency of 11.44% when 30 mol% NH4SCN is applied. Notably, the addition of NH4SCN is found to enhance the moisture stability of the perovskite. As a result, the planar PVSCs with 30 mol% NH4SCN additive show improved stability under ambient conditions (RH: 30–40%) over those based on pristine FAPbI3. NH4SCN simultaneously enhances the efficiency and moisture stability of FAPbI3 based PVSCs through a single one-step solution method, facilitating their commercial fabrication and application.
Co-reporter:Peipei Yin, Gang Wu, Wenlong Qin, Xiaoqiang Chen, Mang Wang and Hongzheng Chen
Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN849-849
Publication Date(Web):2012/11/29
DOI:10.1039/C2TC00344A
Chromatic organic pigment–SiO2 composite particles with six different colors (CYM and RGB) were prepared by a modified sol–gel method. With the aid of a cationic polyelectrolyte, poly(diallyldimethylammoniumchloride), amorphous silica was coated onto the surface of organic pigments which was revealed by the variation of the zeta potential and average particle size, together with TEM images and EDX and XPS results. Because of the fine scattering properties of silica to visible light, the intensity of the reflectance peak increased significantly, which makes the composite particles more vivid than the organic pigments. The chromatic electrophoretic suspension was prepared by mixing Span 85 and the composite particles anchored with a self-made block copolymer PLMA-b-PDMAEMA in tetrachloroethylene. All the colored ink particles have similar zeta potentials and mobility of about 30 mV and 4–5 × 10−10 m2 V−1 s−1, respectively. White/color (CYM and RGB) dual-particle electronic ink containing PLMA-b-PDMAEMA treated pigment–SiO2 composite particles and TiO2 grafted with a polymer present excellent performance and quick response under an applied DC field of 0.15 V μm−1.
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