Co-reporter:Guobiao Xue, Xikang Zhao, Ge Qu, Tianbai Xu, Aristide Gumyusenge, Zhuorui Zhang, Yan Zhao, Ying Diao, Hanying Li, and Jianguo Mei
ACS Applied Materials & Interfaces August 2, 2017 Volume 9(Issue 30) pp:25426-25426
Publication Date(Web):July 13, 2017
DOI:10.1021/acsami.7b07624
The selection of side chains is important in design of conjugated polymers. It not only affects their intrinsic physical properties, but also has an impact on thin film morphologies. Recent reports suggested that a face-on/edge-on bimodal orientation observed in polymer thin films may be responsible for a three-dimensional (3D) charge transport and leads to dramatically improved mobility in donor–acceptor based conjugated polymers. To achieve a bimodal orientation in thin films has been seldom explored from the aspect of molecular design. Here, we demonstrate a design strategy involving the use of asymmetric side chains that enables an isoindigo-based polymer to adopt a distinct bimodal orientation, confirmed by the grazing incidence X-ray diffraction. As a result, the polymer presents an average high mobility of 3.8 ± 0.7 cm2 V–1 s–1 with a maximum value of 5.1 cm2 V–1 s–1, in comparison with 0.47 and 0.51 cm2 V–1 s–1 obtained from the two reference polymers. This study exemplifies a new strategy to develop the next generation polymers through understanding the property-structure relationship.Keywords: asymmetric side chains; bimodal orientation; field-effect transistors; isoindigo-based polymers; three-dimensional charge transport;
Co-reporter:Ze-Hua Wu;Zhuo-Ting Huang;Rui-Xue Guo;Dr. Chun-Lin Sun;Li-Chuan Chen;Bing Sun; Zi-Fa Shi; Xiangfeng Shao; Hanying Li; Hao-Li Zhang
Angewandte Chemie International Edition 2017 Volume 56(Issue 42) pp:13031-13035
Publication Date(Web):2017/10/09
DOI:10.1002/anie.201707529
AbstractThe design and synthesis of high-performance n-type organic semiconductors are important for the development of future organic optoelectronics. Facile synthetic routes to reach the K-region of pyrene and produce 4,5,9,10-pyrene diimide (PyDI) derivatives are reported. The PyDI derivatives exhibited efficient electron transport properties, with the highest electron mobility of up to 3.08 cm2 V−1 s−1. The tert-butyl-substituted compounds (t-PyDI) also showed good one- and two-photon excited fluorescence properties. The PyDI derivatives are a new family of aromatic diimides that may exhibit both high electron mobility and good light-emitting properties, thus making them excellent candidates for future optoelectronics.
Co-reporter:Ze-Hua Wu;Zhuo-Ting Huang;Rui-Xue Guo;Dr. Chun-Lin Sun;Li-Chuan Chen;Bing Sun; Zi-Fa Shi; Xiangfeng Shao; Hanying Li; Hao-Li Zhang
Angewandte Chemie 2017 Volume 129(Issue 42) pp:13211-13215
Publication Date(Web):2017/10/09
DOI:10.1002/ange.201707529
AbstractThe design and synthesis of high-performance n-type organic semiconductors are important for the development of future organic optoelectronics. Facile synthetic routes to reach the K-region of pyrene and produce 4,5,9,10-pyrene diimide (PyDI) derivatives are reported. The PyDI derivatives exhibited efficient electron transport properties, with the highest electron mobility of up to 3.08 cm2 V−1 s−1. The tert-butyl-substituted compounds (t-PyDI) also showed good one- and two-photon excited fluorescence properties. The PyDI derivatives are a new family of aromatic diimides that may exhibit both high electron mobility and good light-emitting properties, thus making them excellent candidates for future optoelectronics.
Co-reporter:Lijian Zuo;Shuhua Zhang;Minmin Shi;Hongzheng Chen
Materials Chemistry Frontiers 2017 vol. 1(Issue 2) pp:304-309
Publication Date(Web):2017/02/16
DOI:10.1039/C6QM00043F
Successfully transferring the device efficiency of small area organic solar cells (SA-OSCs) to a large scale area is a tough challenge. The charge collecting and transporting grids are demonstrated to be effective at addressing this issue, and are widely used in commercial silicon solar cells. However, appreciable shadow loss (5–10%) can be caused with these grids. Thus, a rational design of the grid structure to reduce this significant shadow loss is highly desired. Here, we show that the significant energy loss on scaling up the OSC area stems from the accumulated current density along the charge transport direction. Accordingly, a rational pattern of shorter and triangular Ag grids is designed to accommodate the accumulated current density, leading to a high efficiency of 6.93% for up-scaled OSCs of 4 cm2.
Co-reporter:Tao Ye, Xin-Yi Jin, Liao Chen, Chong Hu, ... Han-Ying Li
Chinese Chemical Letters 2017 Volume 28, Issue 4(Volume 28, Issue 4) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.cclet.2016.12.005
Synthetic calcite single crystals, due to their strong crystal habit, tend to grow into characteristic rhombohedra. In the nature, biogenic calcite crystals form composites together with biomacromolecular materials, spurring investigations of how the growing calcite single crystals change their habit to satisfy the curvature of the organic phase. In this work, we examine calcite crystallization on a flat surface of glass slide and a curved surface of polystyrene (PS) sphere. The crystals exhibit tiny contact area onto the glass substrate that is averagely only 15% of their projected area on the substrate. In sharp contrast, the contact area greatly increase to above 75% of the projected area, once magnesium ions or agarose gel networks are introduced into the crystallization media. Furthermore, the calcite crystals form rough and step-like interfaces with a curved surface. However, the interfaces become smooth and curved as the crystals grow in presence of magnesium ions or agarose gel networks. The discrepancy between the interfacial structures implies kinetic effects of the additives on the crystallization around the surfaces. This work may provide implications for understanding the formation mechanisms of single-crystal composite materials.Download high-res image (189KB)Download full-size imageThe addition of magnesium or the incorporation of agarose gel-networks can change the crystallization kinetics of calcite to accommodate the curvature of foreign solids.
Co-reporter:Qinfen Li;Jiake Wu;Ruihan Wu;Yujing Liu;Hongzheng Chen
Science China Chemistry 2017 Volume 60( Issue 4) pp:490-496
Publication Date(Web):2017 April
DOI:10.1007/s11426-016-9018-y
Contact resistance at the interface between metal electrodes and semiconductors can significantly limit the performance of organic field-effect transistors, leading to a distinct voltage drop at the interface. Here, we demonstrate enhanced performance of n-channel field-effect transistors based on solution-grown C60 single-crystalline ribbons by introducing an interlayer of a conjugated polyelectrolyte (CPE) composed of poly[(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] dibromide (PFN+Br−). The PFN+Br− interlayer greatly improves the charge injection. Consequently, the electron mobility is promoted up to 5.60 cm2 V−1 s−1 and the threshold voltage decreased dramatically with the minimum of 4.90 V.
Co-reporter:Guobiao Xue, Jiake Wu, Congcheng Fan, Shuang Liu, Zhuoting Huang, Yujing Liu, Bowen Shan, Huolin L. Xin, Qian Miao, Hongzheng Chen and Hanying Li
Materials Horizons 2016 vol. 3(Issue 2) pp:119-123
Publication Date(Web):29 Oct 2015
DOI:10.1039/C5MH00190K
Enhancing electron transport to match with the development in hole transport is critical for organic electronics in the future. As electron motion is susceptible to extrinsic factors, seeking these factors and avoiding their negative effects have become the central challenge. Here, the existence of polar solvent residues in solution-grown single-crystals of 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene is identified as a factor detrimental to electron motion. Field-effect transistors of the crystals exhibit electron mobility boosted by about 60% after the residues are removed. The average electron mobility reaches up to 8.0 ± 2.2 cm2 V−1 s−1 with a highest value of 13.3 cm2 V−1 s−1; these results are significantly higher than those obtained previously for the same molecule (1.0–5.0 cm2 V−1 s−1). Furthermore, the achieved mobility is also higher than the maximum reported electron mobility for organic materials (11 cm2 V−1 s−1). This work should greatly accelerate the advancement of organic electron-transporting materials.
Co-reporter:Yujing Liu, Huidong Zang, Ling Wang, Weifei Fu, Wentao Yuan, Jiake Wu, Xinyi Jin, Jishu Han, Changfeng Wu, Yong Wang, Huolin L. Xin, Hongzheng Chen, and Hanying Li
Chemistry of Materials 2016 Volume 28(Issue 20) pp:7537
Publication Date(Web):September 25, 2016
DOI:10.1021/acs.chemmater.6b03589
Incorporation of guest materials inside single-crystalline hosts leads to single-crystal composites that have become more and more frequently seen in both biogenic and synthetic crystals. The unique composite structure together with long-range ordering promises special properties that are, however, less often demonstrated. Here, we examine the fluorescent properties of quantum dots (QDs) and polymer dots (Pdots) encapsulated inside the hosts of calcite single-crystals. Two CdTe QDs and two Pdots are incorporated into growing calcite crystals, as the QDs and Pdots are dispersed in the crystallization media of agarose gels. As a result, enhanced fluorescent properties are obtained from the QDs and Pdots inside calcite single-crystals with greatly improved photostability and significantly prolonged fluorescence lifetime, compared to those in solutions and gels. Particularly, the fluorescence lifetime increases by 0.5–1.6 times after the QDs or Pdots are incorporated. The enhanced fluorescent properties indicate the advantages of encapsulation by single-crystal hosts that provide dense shells to isolate the fluorescent nanoparticles from atmosphere. As such, this work has implications for advancing the research of single-crystal composites toward their functional design.
Co-reporter:Tao Ye, Weifei Fu, Jiake Wu, Zhikai Yu, Xinyi Jin, Hongzheng Chen and Hanying Li
Journal of Materials Chemistry A 2016 vol. 4(Issue 4) pp:1214-1217
Publication Date(Web):22 Dec 2015
DOI:10.1039/C5TA10155G
We have successfully grown single-crystalline lead halide perovskite arrays on a poly(3,4-ethylene dioxythiophene):polystyrenesulfonic acid (PEDOT:PSS) coated ITO substrate by the droplet-pinned crystallization (DPC) method and, for the first time, single-crystalline perovskite solar cells have been fabricated with a power conversion efficiency of 1.73%.
Co-reporter:Weifei Fu, Jielin Yan, Zhongqiang Zhang, Tao Ye, Yujing Liu, Jiake Wu, Jizhong Yao, Chang-Zhi Li, Hanying Li, Hongzheng Chen
Solar Energy Materials and Solar Cells 2016 Volume 155() pp:331-340
Publication Date(Web):October 2016
DOI:10.1016/j.solmat.2016.06.037
•Two PbI2(X) complexes with different coordination strength of ligand X are synthesized.•Correlations between morphology, carrier lifetime and photovoltaic performance are investigated with various PbI2(X).•Highly efficient inverted planar perovskite solar cells with power conversion efficiency up to 17.0% are achieved.Lead halide complexes are efficient precursors to obtain high quality perovskite films and high performance solar cells. However, how the lead halide complex affects the crystallization kinetics and thus the film quality of perovskite has not been systematically studied. Herein, two PbI2(X) complexes with different coordination strength of ligand X in complexation with PbI2 (PbI2(DMF) and PbI2(DMSO)) are synthesized. The correlation between the morphology, evolution of the perovskite formation, defects state, carrier lifetime and the subsequent photovoltaic performance are investigated in details via a two-step coating method with various PbI2(X) complexes. We find that PbI2(DMSO) derived perovskite film shows larger grains and vertically oriented grain boundaries as well as enhanced photoluminescence intensity and longer carrier lifetime. As a result, highly efficient inverted planar perovskite solar cells with a power conversion efficiency up to 17.0% are achieved from PbI2(DMSO) complex under 1 sun illumination. This research could open up a new pathway to further improve the performance of perovskite solar cells through the control of perovskite crystallization kinetics by choosing proper PbI2(X) complex precursors.
Co-reporter:Jie Ren, Boning Huang, Liao Chen, Yujing Liu, Tao Ye, Wei Liu, Xinyi Jin, Zhi-Kang Xu, Hongzheng Chen and Hanying Li
CrystEngComm 2016 vol. 18(Issue 5) pp:800-806
Publication Date(Web):23 Dec 2015
DOI:10.1039/C5CE02383A
Single crystals of organic semiconductors are promising for high-performance semiconducting materials by virtue of their superior charge mobilities. Interfacing these single crystals with other foreign materials is needed to fabricate varied electronic devices. However, it is difficult to construct interfaces inside a single crystal that is typically homogeneous. In this work, single crystals of two typical organic semiconductors, anthracene and 9,10-diphenylanthracene, were grown from both silica gels and phenyl-modified silica gels. X-ray diffraction analysis demonstrated their single crystallinity. Examination of the residues which remained after sublimation of the gel-grown crystals revealed that the single crystals grown from phenyl-modified silica gels incorporated the gel networks, with the gel networks penetrating through the crystal in three-dimensional space, whereas the silica gel-grown crystals did not. This discrepancy suggests that the affinity between the crystal and the gel network favours gel incorporation. As such, our work provides a potential way to fabricate bulk contact between single crystals of organic semiconductors and foreign materials through gel crystallization.
Co-reporter:Qin-Fen Li, Shuang Liu, Hong-Zheng Chen, Han-Ying Li
Chinese Chemical Letters 2016 Volume 27(Issue 8) pp:1421-1428
Publication Date(Web):August 2016
DOI:10.1016/j.cclet.2016.06.027
Organic field-effect transistors are of great importance to electronic devices. With the emergence of various preparation techniques for organic semiconductor materials, the device performance has been improved remarkably. Among all of the organic materials, single crystals are potentially promising for high performances due to high purity and well-ordered molecular arrangement. Based on organic single crystals, alignment and patterning techniques are essential for practical industrial application of electronic devices. In this review, recently developed methods for crystal alignment and patterning are described.With the development of organic electronics based on single crystals, alignment and patterning techniques are urgently needed in practical and industrial applications. In this review, newly developed methods for crystal alignment and patterning are depicted.
Co-reporter:Zhuo-Ting Huang, Cong-Cheng Fan, Guo-Biao Xue, Jia-Ke Wu, Shuang Liu, Huan-Bin Li, Hong-Zheng Chen, Han-Ying Li
Chinese Chemical Letters 2016 Volume 27(Issue 4) pp:523-526
Publication Date(Web):April 2016
DOI:10.1016/j.cclet.2016.01.054
Field-effect transistors (FETs) of three diketopyrrolopyrroles (DPP)-based small molecules, 3,6-bis(5-phenylthiophene-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione (PDPPP), 3,6-bis(5-(4-fluorophenyl)thiophene-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione (FPDPPPF) and 3,6-bis(5-(4-n-butylphenyl)thiophene-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione (BuPDPPPBu), have been studied in this work. Well aligned crystals of the three molecules were grown from para-xylene by droplet-pinned crystallization method. FETs based on these aligned crystals exhibit a hole mobility up to 0.19 cm2 V−1 s−1 and electron mobility up to 0.008 cm2 V−1 s−1. The achieved hole mobility is of the same order of magnitude as reported highest hole mobility for DPP-based small molecules, but it is much lower than that of the high-performance DPP-based polymers. The relative low mobility is mainly attributed to the rough crystal surfaces with steps and, thus, non-smooth charge transport channels at the interfaces between the crystals and the dielectrics. This work has implications for understanding the low charge mobility of DPP-based small molecules.Aligned crystals of three DPP-based small molecules grown from para-xylene by droplet-pinned crystallization (DPC) method.
Co-reporter:Jiake Wu;Congcheng Fan;Guobiao Xue;Tao Ye;Shuang Liu;Ruoqian Lin;Hongzheng Chen;Huolin L. Xin;Ren-Gen Xiong
Advanced Materials 2015 Volume 27( Issue 30) pp:4476-4480
Publication Date(Web):
DOI:10.1002/adma.201501577
Co-reporter:Lijian Zuo; Zhuowei Gu; Tao Ye; Weifei Fu; Gang Wu; Hanying Li;Hongzheng Chen
Journal of the American Chemical Society 2015 Volume 137(Issue 7) pp:2674-2679
Publication Date(Web):February 4, 2015
DOI:10.1021/ja512518r
Morphology control is critical to achieve high efficiency CH3NH3PbI3 perovskite solar cells (PSC). The surface properties of the substrates on which crystalline perovskite thin films form are expected to affect greatly the crystallization and, thus, the resulting morphology. However, this topic is seldom examined in PSC. Here we developed a facile but efficient method of modifying the ZnO-coated substrates with 3-aminopropanioc acid (C3-SAM) to direct the crystalline evolution and achieve the optimal morphology of CH3NH3PbI3 perovskite film. With incorporation of the C3-SAM, highly crystalline CH3NH3PbI3 films were formed with reduced pin-holes and trap states density. In addition, the work function of the cathode was better aligned with the conduction band minimum of perovskite for efficient charge extraction and electronic coupling. As a result, the PSC performance remarkably increased from 9.81(±0.99)% (best 11.96%) to 14.25(±0.61)% (best 15.67%). We stress the importance of morphology control through substrate surface modification to obtain the optimal morphology and device performance of PSC, which should generate an impact on developing highly efficient PSC and future commercialization.
Co-reporter:Guobiao Xue, Congcheng Fan, Jiake Wu, Shuang Liu, Yujing Liu, Hongzheng Chen, Huolin L. Xin and Hanying Li
Materials Horizons 2015 vol. 2(Issue 3) pp:344-349
Publication Date(Web):21 Jan 2015
DOI:10.1039/C4MH00211C
Charge transport of solution-grown TIPS-pentacene single-crystals depends on the polarity of the used solvents. Crystals grown from non-polar solvents exhibit ambipolar transport (μe 0.020 cm2 V−1 s−1; μh 5.0 cm2 V−1 s−1), while polar solvents suppress electron transport. This work indicates that appropriate selection of solvents should further harvest the n-type behaviors of organic semiconductors.
Co-reporter:Liao Chen, Tao Ye, Xinyi Jin, Jie Ren, Boning Huang, Zhi-Kang Xu, Hongzheng Chen and Hanying Li
CrystEngComm 2015 vol. 17(Issue 42) pp:8113-8118
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5CE01085C
Crystallization in gel media has been occasionally found to result in single crystals with gel networks incorporated inside, extending the gel method with a long history for crystallization into a platform to design the internal composite structures of a crystal. The limited number of gel-incorporated crystals has inspired the investigation on how general gel incorporation is. Crystallization in gels through decomplexation has been widely used to grow crystals with extremely low water solubility, while whether the gel networks are incorporated inside these crystals has not been studied. In this work, crystals of AgCl, AgI and CuCl have been grown in both agarose gels and silica gels by decomplexation. The crystallographic structures of the crystals were identified by powder and/or single X-ray diffraction. The internal hybrid structures were studied by examining the residue materials after gentle etching and complete dissolution of the crystals. When grown from agarose gels containing self-assembled fibrous structures, gel networks were incorporated into single crystals of all the three compounds. In sharp contrast, the gel networks were pushed away when the crystals were grown in silica gels. The discrepancy between the crystals grown from agarose gels and those from silica gels is consistent with the effect of gel strength on gel incorporation. This work may help to harvest gel-incorporated crystals.
Co-reporter: Hanying Li;Congcheng Fan;Weifei Fu;Dr. Huolin L. Xin; Hongzheng Chen
Angewandte Chemie International Edition 2015 Volume 54( Issue 3) pp:956-960
Publication Date(Web):
DOI:10.1002/anie.201408882
Abstract
Organic single crystals are ideal candidates for high-performance photovoltaics due to their high charge mobility and long exciton diffusion length; however, they have not been largely considered for photovoltaics due to the practical difficulty in making a heterojunction between donor and acceptor single crystals. Here, we demonstrate that extended single-crystalline heterojunctions with a consistent donor-top and acceptor-bottom structure throughout the substrate can be simply obtained from a mixed solution of C60 (acceptor) and 3,6-bis(5-(4-n-butylphenyl)thiophene-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione (donor). 46 photovoltaic devices were studied with the power conversion efficiency of (0.255±0.095) % under 1 sun, which is significantly higher than the previously reported value for a vapor-grown organic single-crystalline donor–acceptor heterojunction (0.007 %). As such, this work opens a practical avenue for the study of organic photovoltaics based on single crystals.
Co-reporter: Hanying Li;Congcheng Fan;Weifei Fu;Dr. Huolin L. Xin; Hongzheng Chen
Angewandte Chemie 2015 Volume 127( Issue 3) pp:970-974
Publication Date(Web):
DOI:10.1002/ange.201408882
Abstract
Organic single crystals are ideal candidates for high-performance photovoltaics due to their high charge mobility and long exciton diffusion length; however, they have not been largely considered for photovoltaics due to the practical difficulty in making a heterojunction between donor and acceptor single crystals. Here, we demonstrate that extended single-crystalline heterojunctions with a consistent donor-top and acceptor-bottom structure throughout the substrate can be simply obtained from a mixed solution of C60 (acceptor) and 3,6-bis(5-(4-n-butylphenyl)thiophene-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione (donor). 46 photovoltaic devices were studied with the power conversion efficiency of (0.255±0.095) % under 1 sun, which is significantly higher than the previously reported value for a vapor-grown organic single-crystalline donor–acceptor heterojunction (0.007 %). As such, this work opens a practical avenue for the study of organic photovoltaics based on single crystals.
Co-reporter:Shuang Liu;Jia-Ke Wu;Cong-Cheng Fan;Guo-Biao Xue;Hong-Zheng Chen
Science Bulletin 2015 Volume 60( Issue 12) pp:1122-1127
Publication Date(Web):2015 June
DOI:10.1007/s11434-015-0817-9
A simple solution processing method was developed to grow large-scale well-aligned single crystals including 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), anthracene, tetracene, perylene, C60 and tetracyanoquinodimethane. As pinned by a solid needle, a droplet of semiconductor solution dried into single-crystal arrays on a 1 cm × 2 cm substrate. TIPS-pentacene was used to demonstrate the fabrication of hundreds of field-effect transistors (FETs) with the hole mobility as high as 6.46 cm2 V−1 s−1. As such, this work provides a high-throughput, yet efficient approach for statistical examination on the FET performance of organic single crystals.有机半导体在场效应晶体管、太阳电池、发光二极管、存储器等众多领域具有广泛的应用前景。与有机半导体薄膜相比,其单晶中缺陷密度较小,因而有机单晶通常具有较高的载流子迁移率,使其成为探索有机材料本征性质和构筑高性能光电器件的最佳选择。目前有机单晶器件较多用于基础研究,而其向应用的过渡首先需要解决单晶大面积生长的难题,为单晶器件的大规模制备打下基础。本文采用一种改进的“固定液滴法”,使有机半导体液滴在金属针的固定下,随溶液蒸发,在表面张力的驱动下,由边缘向中心收缩,同时生长出取向一致的大面积有机单晶,并大规模制备了其场效应晶体管阵列,其迁移率居世界前列。这种方法可适用于多种有机半导体材料,从而为大规模制备有机单晶场效应晶体管阵列提供了一种简便高效的方法。
Co-reporter:Ling Wang, Weifei Fu, Zhuowei Gu, Congcheng Fan, Xi Yang, Hanying Li and Hongzheng Chen
Journal of Materials Chemistry A 2014 vol. 2(Issue 43) pp:9087-9090
Publication Date(Web):19 Sep 2014
DOI:10.1039/C4TC01875C
A cadmium selenide (CdSe) nanocrystal was used as an electron transport/extraction layer for perovskite solar cells due to its high electron mobility and solution-processability at low temperatures. Power conversion efficiency (PCE) up to 11.7% was achieved under standard AM1.5G conditions in air.
Co-reporter:Hanying Li, Congcheng Fan, Michael Vosgueritchian, Benjamin C.-K. Tee and Hongzheng Chen
Journal of Materials Chemistry A 2014 vol. 2(Issue 18) pp:3617-3624
Publication Date(Web):25 Feb 2014
DOI:10.1039/C3TC32431A
Single crystals of C60 have been widely prepared previously. However, their electronic properties are much less frequently studied, although C60 is known as an outstanding electronic material. Also, the reported electron mobility values (∼10−2 cm2 V−1 s−1) of C60 single-crystals are unexpectedly low possibly due to the difficulties in the fabrication of single-crystal devices. We have recently reported a droplet receding method for the solution-grown C60 single-crystals with mobilities above 1 cm2 V−1 s−1. In this work, we systematically investigate the effects of solvent and surface properties of the substrate on the growth of C60 single-crystals. Well-aligned C60 needle-like and ribbon-like single-crystals were grown from suitable solvents (m-xylene or a mixed solvent of m-xylene and carbon tetrachloride) conformally on the field-effect transistor (FET) substrates that were wet well by the receding droplet. Based on the ribbon-like single-crystals, an average electron mobility of 2.0 ± 0.61 cm2 V−1 s−1, Ion/Ioff > 106, and a VT between 36 and 85 V were achieved from 60 field-effect transistors. Insights provided by this work may help accelerate the development of solution-grown single-crystals of organic semiconductors.
Co-reporter:Weifei Fu, Ling Wang, Yanfang Zhang, Ruisong Ma, Lijian Zuo, Jiangquan Mai, Tsz-Ki Lau, Shixuan Du, Xinhui Lu, Minmin Shi, Hanying Li, and Hongzheng Chen
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 21) pp:19154
Publication Date(Web):October 22, 2014
DOI:10.1021/am505130a
Achieving superior solar cell performance based on the colloidal nanocrystals remains challenging due to their complex surface composition. Much attention has been devoted to the development of effective surface modification strategies to enhance electronic coupling between the nanocrystals to promote charge carrier transport. Herein, we aim to attach benzenedithiol ligands onto the surface of CdSe nanocrystals in the “face-on” geometry to minimize the nanocrystal–nanocrystal or polymer–nanocrystal distance. Furthermore, the “electroactive” π-orbitals of the benzenedithiol are expected to further enhance the electronic coupling, which facilitates charge carrier dissociation and transport. The electron mobility of CdSe QD films was improved 20 times by tuning the ligand orientation, and high performance poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT):CdSe nanocrystal hybrid solar cells were also achieved, showing a highest power conversion efficiency of 4.18%. This research could open up a new pathway to improve further the performance of colloidal nanocrystal based solar cells.Keywords: charge transport; electronic coupling; exciton dissociation; hybrid solar cell; ligand orientation
Co-reporter:Lijian Zuo, Jizhong Yao, Hanying Li, Hongzheng Chen
Solar Energy Materials and Solar Cells 2014 Volume 122() pp:88-93
Publication Date(Web):March 2014
DOI:10.1016/j.solmat.2013.11.018
•We propose an improved equivalent circuit model to interpret the origin of S shape curve.•The improved equivalent circuit model involves a rectifying junction connected with the D:A junction in series.•The validity of this model is confirmed by good reproduction of the experimental results.•Effect of the formation of S shape curve on device parameters is analyzed through the equivalent model.•Detailed effect of the rectifying junction on the I–V curve of organic solar cells is simulated.Formation of S-shaped I–V curve or the so-called kink has been shown detrimental to organic solar cells (OSC) performance. Previous researches have indicated that a variety of reasons could count for the origin of the S-shaped I–V curve. However, its origin is still not clear. In this contribution, we investigated the origin of S-shaped I–V curve from the view of an equivalent circuit model (ECM) in OSCs. The proposed ECM involves a rectifying junction connected with a donor/accepter (D/A) junction in series. OSCs with and without a Schottky barrier that was a rectifying junction were fabricated to verify the modeled results. And the good reproduction of experimental results confirmed the validity of our model. The results indicate that the origin of S-shaped I–V curve in OSCs is associated with the rectifying junction. With this model, the effects of the rectifying junction on the shape of I–V characteristic and its effect on device parameters are analyzed: fill factor (FF) dropped, short circuit current density decreased, open circuit voltage however, remained. Also, from simulation, we varied the parameters of the rectifying junction to study their influence on the device performance.In this work, we study the origin of S shape curve through an improved equivalent circuit model (ECM). The improved ECM involves a D:A junction as well as a rectifying junction to interpret the bias-dependent-recombination.
Co-reporter:Liao Chen, Tao Ye, Yujing Liu, Wei Liu, Gang Wu, Hongzheng Chen and Hanying Li
CrystEngComm 2014 vol. 16(Issue 30) pp:6901-6906
Publication Date(Web):22 May 2014
DOI:10.1039/C4CE00243A
Gel-grown single-crystal composites where gel networks are incorporated inside single-crystals have been reported in an increasing number of studies, with the composite structure similar to that of the biogenic biomacromolecule-incorporated single-crystals. However, the mechanisms of the gel incorporation are still not clear. In this work, we examined the growth of four types of crystals (NaF, NaCl, KBr and potassium dihydrogen phosphate (KDP)) in both silica gels and agarose gels to assess the effects of the crystal–gel interaction and the gel structure on the gel incorporation. In all of the eight crystal–gel pairs, single-crystals were obtained by single-crystal X-ray diffraction analysis. Dissolution of the crystals revealed that all of the four types of crystals grown from the agarose gels incorporated the gel networks during crystallization. In contrast, NaF and KDP crystals incorporated the silica gel networks but NaCl and KBr did not when grown from silica gels. The discrepancies among the eight crystal–gel pairs suggest that crystal–gel interaction (hydrogen bond) and fibre-like gel structure with large gel strength favour the gel incorporation. This work may facilitate understanding of the formation mechanisms of single-crystal composites.
Co-reporter:Yujing Liu;Liao Chen;Wei Liu;Tao Ye;Hongzheng Chen
Polymers for Advanced Technologies 2014 Volume 25( Issue 11) pp:1189-1194
Publication Date(Web):
DOI:10.1002/pat.3330
Biogenic single-crystals have been found to incorporate biomacromolecules and become biomacromolecule/single-crystal composites. The complex composite structures and properties of these biogenic crystalline materials have spurred investigations to reproduce their synthetic analogs, polymer/single-crystal composites. Here, we review recent progress of the synthetic polymer/single-crystal composites, where the polymers are distributed inside the crystals in their aggregate states (micelles, particles, gel networks, and 3D structured forms). The mechanisms of the polymer incorporation are also discussed. Furthermore, the effects of the polymer incorporation on the properties of the crystal host are described. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Yujing Liu;Wentao Yuan;Ye Shi;Xiaoqiang Chen; Yong Wang; Hongzheng Chen; Hanying Li
Angewandte Chemie 2014 Volume 126( Issue 16) pp:4211-4215
Publication Date(Web):
DOI:10.1002/ange.201310712
Abstract
Synthetic single crystals are usually homogeneous solids. Biogenic single crystals, however, can incorporate biomacromolecules and become inhomogeneous solids so that their properties are also extrinsically regulated by the incorporated materials. The discrepancy between the properties of synthetic and biogenic single crystals leads to the idea to modify the internal structure of synthetic crystals to achieve nonintrinsic properties by incorporation of foreign material. Intrinsically colorless and diamagnetic calcite single crystals are turned into colored and paramagnetic solids, through incorporation of Au and Fe3O4 nanoparticles without significantly disrupting the crystalline lattice of calcite. The crystals incorporate the nanoparticles and gel fibers when grown in agarose gel media containing the nanoparticles, whereas the solution-grown crystals do not. As such, our work extends the long-history gel method for crystallization into a platform to functionalize single-crystalline materials.
Co-reporter:Yujing Liu;Wentao Yuan;Ye Shi;Xiaoqiang Chen; Yong Wang; Hongzheng Chen; Hanying Li
Angewandte Chemie International Edition 2014 Volume 53( Issue 16) pp:4127-4131
Publication Date(Web):
DOI:10.1002/anie.201310712
Abstract
Synthetic single crystals are usually homogeneous solids. Biogenic single crystals, however, can incorporate biomacromolecules and become inhomogeneous solids so that their properties are also extrinsically regulated by the incorporated materials. The discrepancy between the properties of synthetic and biogenic single crystals leads to the idea to modify the internal structure of synthetic crystals to achieve nonintrinsic properties by incorporation of foreign material. Intrinsically colorless and diamagnetic calcite single crystals are turned into colored and paramagnetic solids, through incorporation of Au and Fe3O4 nanoparticles without significantly disrupting the crystalline lattice of calcite. The crystals incorporate the nanoparticles and gel fibers when grown in agarose gel media containing the nanoparticles, whereas the solution-grown crystals do not. As such, our work extends the long-history gel method for crystallization into a platform to functionalize single-crystalline materials.
Co-reporter:Jiachi Huang;Xiong Mo;Minmin Shi
Chemical Research in Chinese Universities 2014 Volume 30( Issue 1) pp:63-67
Publication Date(Web):2014 February
DOI:10.1007/s40242-013-3294-1
One-dimensional crystals of fluorinated perylene diimides were achieved by the self-assembly of them via solvent-nonsolvent exchanging. The π-conjugated fluorinated perylene diimides were assembled into highly-ordered nanostructures of well-defined morphologies in organic solvents due to the π-π interaction between the aromatic cores. It was found that with more introduced F atoms, perylene diimides showed remarkably improved solubility and thus were much easier to grow into crystals, due to the increased polarity induced by the strong electron-withdrawing F group. More importantly, single crystal of N,N′-diperfluorophenyl-3,4,9,10-perylenetetracarboxylic diimide(DPFPP) was obtained, and the unit cell-dimensions of triclinic structure were determined by the selected area electron diffraction( SAED) patterns to be a=0.712 nm, b=1.072 nm, c=2.914 nm, α=97.0°, β=89.6°, γ=93.4°. Owing to most of the longest c-axis orienting nearly vertically to the long axis of the needle crystal, the molecular planes are expected to be vertical to the needle axis.
Co-reporter:Congcheng Fan;Arjan P. Zoombelt;Hao Jiang;Weifei Fu;Jiake Wu;Wentao Yuan;Yong Wang;Hongzheng Chen;Zhenan Bao
Advanced Materials 2013 Volume 25( Issue 40) pp:5762-5766
Publication Date(Web):
DOI:10.1002/adma.201302605
Co-reporter:Ye Shi, Hanying Li, Ling Wang, Wei Shen, and Hongzheng Chen
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 9) pp:4800
Publication Date(Web):August 15, 2012
DOI:10.1021/am3011516
Various semiconductors have been studied as photocatalysts for photocatalytic degradation of pollutants in aqueous solutions. As one of the promising visible-light-driven semiconductor photocatalysts, α-Fe2O3 has advantages of low cost and stability. However, its application is inhibited by the poor separation of photogenerated electron-hole pair. In this work, hybrid structures were prepared to improve the performance of α-Fe2O3. CdS nanoparticles were overgrown on the preformed single-crystalline α-Fe2O3 nanorods by a simple and mild one-step wet-chemical method, resulting in α-Fe2O3/CdS cornlike nanocomposites. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy showed the α-Fe2O3/CdS core/shell heterostructure of the nanocomposite with high crystallinity. Furthermore, the cornlike nanocomposites exhibited superior photocatalytic performances under visible light irradiation over the pure α-Fe2O3 nanorods and CdS nanoparticles. The photocatalytic activity of the composites is superior to the previously-reported pure α-Fe2O3 nanomaterials, and the performance is comparable to both the commercial TiO2 (P25) which is used under UV irradiation and the newly developed α-Fe2O3/SnO2 photocatalyst under visible light irradiation. The enhanced performance is associated with the larger surface area of the cornlike structure, the crystalline nature of the materials and the synergy in light absorption and charge separation between α-Fe2O3 and CdS. As such, our α-Fe2O3/CdS cornlike nanocomposites may be promising to be used as visible-light-driven high-performance photocatalyst.Keywords: CdS; hybrid materials; photocatalyst; semiconductors; visible-light-driven; α-Fe2O3;
Co-reporter:Hanying Li, Jianguo Mei, Alexander L. Ayzner, Michael F. Toney, Jeffrey B.-H. Tok, Zhenan Bao
Organic Electronics 2012 Volume 13(Issue 11) pp:2450-2460
Publication Date(Web):November 2012
DOI:10.1016/j.orgel.2012.07.011
Thin-film field-effect transistors (FETs) are widely used to evaluate charge transport properties of semiconducting polymers. Discovery of high performance materials require design and synthesis of new polymers. However, most polymers require multi-step synthesis and are difficult to be obtained in a large scale for comprehensive device evaluations. Here, we report a simple method to cast semiconducting polymer films from solutions with polymer concentration as low as 0.5 mg/mL, which is substantially less than typical values (∼10 mg/mL) used in conventional spin coating method. Here, we demonstrate that using this method, our cast films of a previously-reported polymer (PDPP-TT2T) exhibited field-effect mobility (μhole = 0.89 ± 0.13 cm2 V−1 s−1, μe = 0.025 ± 0.005 cm2 V−1 s−1), which is comparable to the reported values using the same device geometry. Furthermore, we extend this method to examine cast films of a pair of polymers (PDPP-3T-Ref, PDPP-3T-Si) to study the effect of siloxane substitution in the side chains on the molecular packing and their subsequent FET performance. We observed that shorter π-stacking distance (3.61 Å) for the siloxane-terminated polymer, when compared to that for the reference polymer (3.73 Å), resulted in improved FET performance (e.g., μhole = 0.63 ± 0.046 cm2 V−1 s−1 for PDPP-3T-Si vs μhole = 0.17 ± 0.062 cm2 V−1 s−1 for PDPP-3T-Ref). Taken together, this work presents an efficient alternative film-casting approach to produce polymer FETs that consumes much less material for their fabrication, lending viability for evaluation of various polymeric materials.Graphical abstractHighlights► Uniform polymer films were cast using a simple drop-pinned method. ► The casting method consumed much less material than conventional spin casing. ► The polymer films exhibited comparable high charge mobility as spin cast films. ► A pair of polymers with branched alkyl side chains or siloxane group were examined. ► Siloxane substitution led to structural modification in favor of charge transport.
Co-reporter:Shi-Yong Liu, Han-Ying Li, Min-Min Shi, Hao Jiang, Xiao-Lian Hu, Wang-Qiu Li, Lei Fu, and Hong-Zheng Chen
Macromolecules 2012 Volume 45(Issue 22) pp:9004-9009
Publication Date(Web):November 5, 2012
DOI:10.1021/ma3019238
Conjugated polymers are the primary blocks for organic electronics. Traditionally, conjugated polymers synthesized via Suzuki, Heck, and Stille couplings are catalyzed by soluble homogeneous ligated palladiums, which suffer the contaminations of residual nano-palladium and phosphine impurity resulting from side reaction of aryl–aryl exchange. To overcome these drawbacks, a commercially available, clean, and ligand-free heterogeneous catalyst Pd/C for the C–C coupling polymerizations was developed in this work. The Pd/C catalyst showed increases in catalytic activity for Suzuki and Heck polymerizations, as compared with the classical homogeneous catalyst Pd(PPh3)4. Furthermore, the Pd/C catalyst exhibited advantage of much less Pd residue in the resulting polymers, leading to better charge transport properties as demonstrated by field effect transistors.
Co-reporter:Lijian Zuo, Jizhong Yao, Hanying Li, Hongzheng Chen
Solar Energy Materials and Solar Cells (March 2014) Volume 122() pp:88-93
Publication Date(Web):1 March 2014
DOI:10.1016/j.solmat.2013.11.018
•We propose an improved equivalent circuit model to interpret the origin of S shape curve.•The improved equivalent circuit model involves a rectifying junction connected with the D:A junction in series.•The validity of this model is confirmed by good reproduction of the experimental results.•Effect of the formation of S shape curve on device parameters is analyzed through the equivalent model.•Detailed effect of the rectifying junction on the I–V curve of organic solar cells is simulated.Formation of S-shaped I–V curve or the so-called kink has been shown detrimental to organic solar cells (OSC) performance. Previous researches have indicated that a variety of reasons could count for the origin of the S-shaped I–V curve. However, its origin is still not clear. In this contribution, we investigated the origin of S-shaped I–V curve from the view of an equivalent circuit model (ECM) in OSCs. The proposed ECM involves a rectifying junction connected with a donor/accepter (D/A) junction in series. OSCs with and without a Schottky barrier that was a rectifying junction were fabricated to verify the modeled results. And the good reproduction of experimental results confirmed the validity of our model. The results indicate that the origin of S-shaped I–V curve in OSCs is associated with the rectifying junction. With this model, the effects of the rectifying junction on the shape of I–V characteristic and its effect on device parameters are analyzed: fill factor (FF) dropped, short circuit current density decreased, open circuit voltage however, remained. Also, from simulation, we varied the parameters of the rectifying junction to study their influence on the device performance.In this work, we study the origin of S shape curve through an improved equivalent circuit model (ECM). The improved ECM involves a D:A junction as well as a rectifying junction to interpret the bias-dependent-recombination.Download full-size image
Co-reporter:Zhuo-Ting Huang, Guo-Biao Xue, Jia-Ke Wu, Shuang Liu, Huan-Bin Li, Yu-Hui Yang, Feng Yan, Paddy K.L. Chan, Hong-Zheng Chen, Han-Ying Li
Chinese Chemical Letters (December 2016) Volume 27(Issue 12) pp:
Publication Date(Web):December 2016
DOI:10.1016/j.cclet.2016.05.016
The n-channel behavior has been occasionally reported in the organic field-effect transistors (OFETs) that usually exhibit p-channel transport only. Reconfirmation and further examination of these unusual device performances should deepen the understanding on the electron transport in organic semiconductors. 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene), a widely examined p-channel material as Au is used for source-drain electrodes, has recently been reported to exhibit electron transport when grown from non-polar solvent on divinyltetramethyldisiloxanebis (benzocyclobutene) (BCB) dielectric, spurring the study on this unusual electron transport. This paper describes FET characteristics of solution-grown TIPS-pentacene single crystals on five polymer gate dielectrics including polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(4-vinyl phenol) (PVP), poly(vinyl alcohol) (PVA) and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)). In addition to the p-channel behavior, electron transport occurs in the crystals on PMMA, PS, thick PVA (40 nm) and a bilayer dielectric of PMMA on P(VDF-TrFE-CFE), while does not on PVP and thin PVA (2 nm). The two distinct FET characteristics are consistent with the previous reported trap effect of hydroxyl groups (in PVP and PVA) and reduced injection barrier by Na+ ions (as impurity in PVA). The highest electron mobility of 0.48 cm2 V−1 s−1 has been achieved in the crystals on PMMA. Furthermore, the electron transport is greatly attenuated after the crystals are exposed to the vapor of a variety of polar solvents and the attenuated electron transport partially recovers if the crystals are heated, indicating the adverse effect of polar impurities on electron transport. By reconfirming the n-channel behavior in the OFETs based on TIPS-pentacene, this work has implications for the design of n-channel and ambipolar OFETs.The electron mobility of TIPS-pentacene single crystals dropped after the polar solvent vapor treatment, and recovered partially when heating.
Co-reporter:Lijian Zuo, Shuhua Zhang, Minmin Shi, Hanying Li and Hongzheng Chen
Inorganic Chemistry Frontiers 2017 - vol. 1(Issue 2) pp:NaN309-309
Publication Date(Web):2016/08/08
DOI:10.1039/C6QM00043F
Successfully transferring the device efficiency of small area organic solar cells (SA-OSCs) to a large scale area is a tough challenge. The charge collecting and transporting grids are demonstrated to be effective at addressing this issue, and are widely used in commercial silicon solar cells. However, appreciable shadow loss (5–10%) can be caused with these grids. Thus, a rational design of the grid structure to reduce this significant shadow loss is highly desired. Here, we show that the significant energy loss on scaling up the OSC area stems from the accumulated current density along the charge transport direction. Accordingly, a rational pattern of shorter and triangular Ag grids is designed to accommodate the accumulated current density, leading to a high efficiency of 6.93% for up-scaled OSCs of 4 cm2.
Co-reporter:Hanying Li, Congcheng Fan, Michael Vosgueritchian, Benjamin C.-K. Tee and Hongzheng Chen
Journal of Materials Chemistry A 2014 - vol. 2(Issue 18) pp:NaN3624-3624
Publication Date(Web):2014/02/25
DOI:10.1039/C3TC32431A
Single crystals of C60 have been widely prepared previously. However, their electronic properties are much less frequently studied, although C60 is known as an outstanding electronic material. Also, the reported electron mobility values (∼10−2 cm2 V−1 s−1) of C60 single-crystals are unexpectedly low possibly due to the difficulties in the fabrication of single-crystal devices. We have recently reported a droplet receding method for the solution-grown C60 single-crystals with mobilities above 1 cm2 V−1 s−1. In this work, we systematically investigate the effects of solvent and surface properties of the substrate on the growth of C60 single-crystals. Well-aligned C60 needle-like and ribbon-like single-crystals were grown from suitable solvents (m-xylene or a mixed solvent of m-xylene and carbon tetrachloride) conformally on the field-effect transistor (FET) substrates that were wet well by the receding droplet. Based on the ribbon-like single-crystals, an average electron mobility of 2.0 ± 0.61 cm2 V−1 s−1, Ion/Ioff > 106, and a VT between 36 and 85 V were achieved from 60 field-effect transistors. Insights provided by this work may help accelerate the development of solution-grown single-crystals of organic semiconductors.
Co-reporter:Ling Wang, Weifei Fu, Zhuowei Gu, Congcheng Fan, Xi Yang, Hanying Li and Hongzheng Chen
Journal of Materials Chemistry A 2014 - vol. 2(Issue 43) pp:NaN9090-9090
Publication Date(Web):2014/09/19
DOI:10.1039/C4TC01875C
A cadmium selenide (CdSe) nanocrystal was used as an electron transport/extraction layer for perovskite solar cells due to its high electron mobility and solution-processability at low temperatures. Power conversion efficiency (PCE) up to 11.7% was achieved under standard AM1.5G conditions in air.
Co-reporter:Tao Ye, Weifei Fu, Jiake Wu, Zhikai Yu, Xinyi Jin, Hongzheng Chen and Hanying Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 4) pp:NaN1217-1217
Publication Date(Web):2015/12/22
DOI:10.1039/C5TA10155G
We have successfully grown single-crystalline lead halide perovskite arrays on a poly(3,4-ethylene dioxythiophene):polystyrenesulfonic acid (PEDOT:PSS) coated ITO substrate by the droplet-pinned crystallization (DPC) method and, for the first time, single-crystalline perovskite solar cells have been fabricated with a power conversion efficiency of 1.73%.
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