Solubilizing and stabilizing C60 with n-type polymer enables efficient inverted perovskite solar cells
Zhou Xing, Suxiang Ma, Bin‐Wen Chen, Mingwei An, Ajuan Fan, Xiayi Hu, Yang Wang, Lin‐Long Deng, Qiufeng Huang, Hiroyuki Kanda, Fahad Al‐Amri, G. Pozzi, Yi Zhang, Jianxing Xia, Jiazhen Wu, Xugang Guo, Mohammad Khaja Nazeeruddin
Abstract
Pristine fullerene C 60 is currently the best-performing electron transport layer (ETL) for perovskite solar cells (PSCs) but suffers from significant aggregation in solution. Consequently, the high-cost and complex thermal evaporation method is typically used to deposit high-quality C 60 ETLs. To address this challenge, we introduce an n-type polymeric additive that can solubilize and stabilize C 60 molecules for solution processing, leading to efficient and stable solution-processed-C 60 (SP-C 60 ) ETLs. The achievement is attributed to the well-matched properties of the n-type polymer and the precisely controlled intermolecular interactions between the polymer and C 60 . As a result, the SP-C 60 ETL with 5-wt % polymer addition afforded a champion power conversion efficiency of 25.60% (certified 25.09%). This is not only the highest performance among the current SP-C 60 devices but also highly competitive to the state-of-the-art thermally evaporated C 60 devices. Importantly, the champion device showed significantly enhanced stability ( T 95, light > 1,800 h; T 80, heat = 700 h).