Manipulating active layer morphology of molecular donor/polymer acceptor based organic solar cells through ternary blends
The development of molecular donor/polymer acceptor blend (MD/PA)-type organic solar cells (OSCs) lags far behind other type OSCs. It is due to the large-size phase separation morphology of MD/PA blend, which results from the high crystallinity of molecular donors. In this article, to suppress the crystallinity of molecular donors, we use ternary blends to develop OSCs based on one polymer acceptor (P-BNBP-fBT) and two molecular donors (DR3TBDTT and BTR) with similar chemical structures. The ternary OSC exhibits a power conversion efficiency (PCE) of 4.85%, which is higher than those of the binary OSCs (PCE=3.60% or 3.86%). To our best knowledge, it is the first report of ternary MD/PA-type OSCs and this PCE is among the highest for MD/PA-type OSCs reported so far. Compared with the binary blends, the ternary blend exhibits decreased crystalline size and improved face-on orientation of the donors. As a result, the ternary blend exhibits improved and balanced charge mobilities, suppressed charge recombination and increased donor/acceptor interfacial areas, which leads to the higher short-circuit current density. These results suggest that using ternary blend is an effective strategy to manipulate active layer morphology and enhance photovoltaic performance of MD/PA-type OSCs.
Keywordsorganic solar cells molecular donor polymer acceptor blend morphology ternary blend
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This work was supported by the National Key Basic Research and Development Program of China (2014CB643504), the National Natural Science Foundation of China (21625403, 51403200, 21504066, 21534003), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12010200), Jilin Scientific and Technological Development Program (20170519003JH), Ministry of Science and Technology (2016YFA0200700), the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy (DE-AC02- 05CH11231), ARC Future Fellowship (FT130100500) and the ARC Centre of Excellence in Exciton Science (CE170100026). The authors thank Chenhui Zhu at beamline 7.3.3, and Cheng Wang at beamline 220.127.116.11 for assistance with data acquisition. The collaborative work in this project between Australia and China was made possible by funding from the Australian Renewable Energy Agency, the Australian Centre for Advanced Photovoltaics and the International Research & Research Training Fund of the University of Melbourne. Responsibility for the views, information or advice expressed herein is not accepted by the Australian Government.
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