Inverted Perovskite Solar Cells With Acid‐Base Neutralized Self‐Assembled Molecules
Wen Li, Xiaodong Li, Bo Feng, Zhengbo Cui, Wentao He, Chi He, Wenxiao Zhang, Sheng Fu, Junfeng FangABSTRACT
Self‐assembled monolayers (SAMs) have greatly contributed to the recent rapid development of inverted perovskite solar cells (PSCs). However, the acid nature of ‐PO(OH) 2 in SAM commonly induces severe device degradation. Here we propose a universal method to develop neutralized SAM‐N molecule through typical acid‐base reaction between commonly used SAM molecules and methylamine (MA). In comparison with acid SAM (pH of 3), SAM‐N shows neutral nature with pH value of 7, avoiding acid‐induced device degradation. Importantly, SAM‐N molecules can still assemble on neighboring ITO to regulate the work function and promote holes extraction. Resulting Cs 0.05 FA 0.9 MA 0.05 PbI 3 PSCs show high PCE of 26.53%. Besides, long‐term stability is also obtained in MA‐free device (Cs 0.05 FA 0.95 PbI 3 ), with 97.3% of initial efficiency after MPP tracking for 1000 h at 85°C with ISOS‐L‐2 protocol.