Energy & Environmental Science ("Energy and Environmental Science", the latest impact factor of 2018 is 33.250) recently published the research results of the Min Jie research group of the Advanced Research Institute on the spontaneous gain of the open circuit voltage of organic solar cells.
The title of the thesis is "Spontaneous open-circuit voltage gain of fully fabricated organic solar cells caused by elimination of interfacial energy disorder" ("Spontaneous open-circuit voltage gain of fully fabricated organic solar cells caused by elimination of interfacial energy disorder" ("Spontaneous open-circuit voltage gain of fully fabricated organic solar cells caused by elimination of interfacial energy disorder"). Wuhan University is the first signed unit / communication unit, Sun Rui, a master student of the Advanced Research Institute, and Deng Dan, PhD of the National Nano Center, are co-first authors. The corresponding authors are Min Jie, a researcher of the Advanced Institute, and Wei Zhixiang, a researcher of the National Nano Center.
In recent years, the heterojunction organic solar cell prepared by the solution method has gained extensive attention because of its advantages of light weight, flexibility, translucency, and large-area preparation. In the past ten years, through the efforts of scientific researchers, the energy conversion efficiency (PCE) of organic solar cells has achieved a great breakthrough. Based on the development of non-fullerene photovoltaic material systems, the PCE of single junction devices has exceeded 16%. At present, more and more researchers are looking at reducing the energy loss of photovoltaic systems and their devices, thereby increasing the open circuit voltage (Voc) and further improving device efficiency. In this direction, various factors such as state density or energy disorder, charge transfer state, receptor interface, carrier density, recombination, interface molecular orientation, defect state, temperature and light intensity have affected the open circuit voltage (Voc). It is widely discussed.
However, at the interface between the heterojunction active layer and the interface, the influence of the interface surface energy between the components on the energy order has not been studied. In this work, we used BTID-2F: PC71BM as the photoactive layer and zinc oxide (ZnO) as the electron transport layer to prepare an efficient inverted solar cell. We found that without sacrificing the short-circuit current and fill factor of the device, Voc spontaneously increased from 0.807 V to 0.950 V. Through the analysis of the surface energy of each component of the BHJ / ZnO interface and the corresponding wetting coefficient, combined with the study of multiple photovoltaic systems, we revealed the origin of the Voc spontaneous gain in OSCs. This work not only provides a useful design concept for material development, but also provides more general design rules for the frozen active layer morphology.
The research work was supported by the National Natural Science Foundation of China (21702154, 51773157), “Double First Class†university construction funding (2042017kf0269) and Wuhan University Self-Study Fund. (Correspondent Xie Zhangbin)
Figure 1: BTID-2F: PC71BM active layer at the ZnO interface, the film morphological characteristics of the schematic change with time; also depicts the evolution of the relevant physical mechanism under such interface morphology changes.
Figure 2: The surface energy of the small molecule donor material BTID-2F, the acceptor material PC71BM, the electron transport layer ZnO, and the hole transport layer PEDOT: PSS and the related wetting coefficient (Figure 2b).
Paint Roller,Roller Paint Brush,Long Roller Paint Brush,Foam Roller Paint Brush
Laizhou Chenke trading Co., Ltd. , https://www.chenkegroup.com