| Abstract: | Two‐dimensional (2D) homologous perovskites are arousing intense interest in photovoltaics and light‐emitting fields, attributing to significantly improved stability and increasing optoelectronic performance. However, investigations on 2D homologous perovskites with ultrathin thickness and large lateral dimension have been seldom reported, being mainly hindered by challenges in synthesis. A generalized self‐doping directed synthesis of ultrathin 2D homologous (BA)2(MA)n −1Pbn Br3n +1 (1<n <∞) perovskites uses 2D (BA)2PbBr4 perovskites as the template with MA+ dopant. Ultrathin (BA)2(MA)n −1Pbn Br3n +1 perovskites are formed via an intercalation–merging mechanism, with thickness shrinking down to 4.2 nm and the lateral dimension to 57 μm. The ultrathin 2D homologous (BA)2(MA)n −1Pbn Br3n +1 perovskites are potential materials for photodetectors with promising photoresponse and stability. |
