Co-reporter:Yong Zhao, Chunjun Liang, Huimin Zhang, Dan Li, Ding Tian, Guobao Li, Xiping Jing, Wenguan Zhang, Weikang Xiao, Qian Liu, Fujun Zhang and Zhiqun He
Energy & Environmental Science 2015 vol. 8(Issue 4) pp:1256-1260
Publication Date(Web):12 Feb 2015
DOI:10.1039/C4EE04064C
It is proved that a large amount of mobile ions exist in organic–inorganic halide perovskites. The accumulated ions at the interface change the band bending of the semiconductor, leading to polarity-switchable photovoltaic devices. The interface charge significantly influences the function and performance of perovskite devices. The discovery of the interface charge has important implications for current–voltage hysteresis in perovskite solar cells.
Co-reporter:Huimin Zhang;Hong Lin;Hong Liu;Jingjing Liang;Yong Zhao;Wenguan Zhang;Mengjie Sun;Weikang Xiao;Han Li;Stefano Polizzi;Dan Li;Fujun Zhang;Zhiqun He;Wallace C. H. Choy
Advanced Functional Materials 2015 Volume 25( Issue 46) pp:7226-7232
Publication Date(Web):
DOI:10.1002/adfm.201502962
While perovskite light-emitting diodes typically made with high work function anodes and low work function cathodes have recently gained intense interests. Perovskite light-emitting devices with two high work function electrodes with interesting features are demonstrated here. Firstly, electroluminescence can be easily obtained from both forward and reverse biases. Secondly, the results of impedance spectroscopy indicate that the ionic conductivity in the iodide perovskite (CH3NH3PbI3) is large with a value of ≈10−8 S cm−1. Thirdly, the shift of the emission spectrum in the mixed halide perovskite (CH3NH3PbI3−xBrx) light-emitting devices indicates that I− ions are mobile in the perovskites. Fourthly, this work shows that the accumulated ions at the interfaces result in a large capacitance (≈100 μF cm−2). The above results conclusively prove that the organic–inorganic halide perovskites are solid electrolytes with mixed ionic and electronic conductivity and the light-emitting device is a light-emitting electrochemical cell. The work also suggests that the organic–inorganic halide perovskites are potential energy-storage materials, which may be applicable in the field of solid-state supercapacitors and batteries.
Co-reporter:Huimin Zhang, Chunjun Liang, Yong Zhao, Mengjie Sun, Hong Liu, Jingjing Liang, Dan Li, Fujun Zhang and Zhiqun He
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 15) pp:9613-9618
Publication Date(Web):05 Mar 2015
DOI:10.1039/C5CP00416K
The accumulation of mobile ions causes space charge at interfaces in perovskite solar cells. There is a slow dynamic process of ion redistribution when the bias is changed. The interface charge affects band bending and thus the photocurrent of the solar cells. Consequently the dynamic process of the interface charge governs the current–voltage hysteresis. Very low interface charge density leads to hysteresis-free devices.
Co-reporter:Dan Li, Jingjing Meng, Yuan Niu, Hongmin Zhao, Chunjun Liang
Chemical Physics Letters 2015 Volume 627() pp:13-19
Publication Date(Web):1 May 2015
DOI:10.1016/j.cplett.2015.03.028
Highlights
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The low-loss mechanism of organic–inorganic perovskites was understood.
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The electronic structures of nine halide perovskites were investigated.
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The spatial separation influenced the recombination rate of electrons and holes.
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Excellent optical absorption was found for all calculated APbI3 perovskites.
Co-reporter:Chunjun Liang, Yongsheng Wang, Dan Li, Xingchen Ji, Fujun Zhang, Zhiqun He
Solar Energy Materials and Solar Cells 2014 Volume 127() pp:67-86
Publication Date(Web):August 2014
DOI:10.1016/j.solmat.2014.04.009
This review summarizes the optical and electrical models of bulk heterojunction (BHJ) polymer solar cells (PSCs) and numerically simulates and analyzes the performance of the PSCs. A complete simulation of a conventional BHJ device based on the polymer P3HT is presented and results are compared with the experimental data. Key factors affecting the device performance, including the photo absorption, quantum efficiency, short-circuit current, fill factor, and open-circuit voltage of the device, are analyzed and summarized. Simulations on inverted, semitransparent, and large-area PSCs are performed and findings are compared with experimental results. Simulations reveal the effects of optical spacer layers, different thicknesses, carrier mobilities, light intensities, contact barriers, effective bandgaps, recombination coefficients, and energy-level bending on the quantum efficiency, short-circuit current, fill factor, and open-circuit voltage of the PSCs. Differences between conventional and inverted geometry, opacity and semitransparency, and small and large-area PSCs are discussed based on the simulations. A power conversion efficiency of 11.0% is predicted for the PSC based on P3HT. Results suggest the need to further reduce the series resistance in large-area PSCs.
Co-reporter:Chunjun Liang, Yongsheng Wang, Dan Li, Xingchen Ji, Fujun Zhang, Zhiqun He
Solar Energy Materials and Solar Cells (August 2014) Volume 127() pp:67-86
Publication Date(Web):1 August 2014
DOI:10.1016/j.solmat.2014.04.009
This review summarizes the optical and electrical models of bulk heterojunction (BHJ) polymer solar cells (PSCs) and numerically simulates and analyzes the performance of the PSCs. A complete simulation of a conventional BHJ device based on the polymer P3HT is presented and results are compared with the experimental data. Key factors affecting the device performance, including the photo absorption, quantum efficiency, short-circuit current, fill factor, and open-circuit voltage of the device, are analyzed and summarized. Simulations on inverted, semitransparent, and large-area PSCs are performed and findings are compared with experimental results. Simulations reveal the effects of optical spacer layers, different thicknesses, carrier mobilities, light intensities, contact barriers, effective bandgaps, recombination coefficients, and energy-level bending on the quantum efficiency, short-circuit current, fill factor, and open-circuit voltage of the PSCs. Differences between conventional and inverted geometry, opacity and semitransparency, and small and large-area PSCs are discussed based on the simulations. A power conversion efficiency of 11.0% is predicted for the PSC based on P3HT. Results suggest the need to further reduce the series resistance in large-area PSCs.
Co-reporter:Huimin Zhang, Chunjun Liang, Yong Zhao, Mengjie Sun, Hong Liu, Jingjing Liang, Dan Li, Fujun Zhang and Zhiqun He
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 15) pp:NaN9618-9618
Publication Date(Web):2015/03/05
DOI:10.1039/C5CP00416K
The accumulation of mobile ions causes space charge at interfaces in perovskite solar cells. There is a slow dynamic process of ion redistribution when the bias is changed. The interface charge affects band bending and thus the photocurrent of the solar cells. Consequently the dynamic process of the interface charge governs the current–voltage hysteresis. Very low interface charge density leads to hysteresis-free devices.
