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Performance Enhancement of Inverted Perovskite Solar Cells Based on Smooth and Compact PC61BM:SnO2 Electron Transport Layers

Wang, Yao, Duan, Chenghao, Li, Jiangsheng, Han, Wei, Zhao, Min, Yao, Lili, Wang, Yuanyuan, Yan, Chao, Jiu, Tonggang
ACS applied materials & interfaces 2018 v.10 no.23 pp. 20128-20135
dispersibility, electron transfer, nanocrystals, solar cells, tin dioxide
In this work, PC₆₁BM:SnO₂ electron transport layers (ETLs) were applied in inverted CH₃NH₃PbI₃ perovskite solar cells, and a high power conversion efficiency of 19.7% could be obtained. It increased by 49.0% in comparison with the device based on PC₆₁BM-only ETL (13.2%). SnO₂ nanocrystals with excellent dispersibility were employed here to fill the pinholes and cover the valleys of PC₆₁BM layer, forming smooth and compact PC₆₁BM:SnO₂ layers. Simultaneously, the electron traps caused by deep-level native defects of SnO₂ were reduced by PC₆₁BM, proved by the space charge limited current analysis. Thus, PC₆₁BM:SnO₂ ETLs can inhibit both of the defects in PC₆₁BM and SnO₂ layers which contribute to the electron transport improvement and reduce the recombination loss. Moreover, the device stability based on the bilayer was significantly improved in comparison with the PC₆₁BM-only device and the performance of 85% could be maintained after 1 month.