2D Perovskite‐Based Self‐Aligned Lateral Heterostructure Photodetectors Utilizing Vapor Deposition

Abstract 2D organic–inorganic hybrid perovskites (OIPs) hold great promise for electronics and optoelectronics due to structural diversity, high photoluminescence, and tunable bandgap. Moreover, integrating 2D OIPs with the 2D materials including graphene, transition metal dichalcogenide, and other OIPs gives opportunities for various options in constructing new types of heterojunctions with novel functionalities such as enhanced charge transport properties or chemical stability. Here, a sequential vapor deposition method is presented to fabricate 2D OIP lateral heterostructure films (C 4 H 9 NH 3 ) 2 PbI 4 (BA 2 PbI 4 )–(C 4 H 9 NH 3 ) 2 (CH 3 NH 3 )Pb 2 I 7 (BA 2 MAPb 2 I 7 ) for photodetector applications. The lateral heterostructure is realized using thermal evaporation to deposit lead iodide (PbI 2 ) films, then exploiting vapor transport of organic vapor to form BA 2 PbI 4 , BA 2 MAPb 2 I 7 , and self‐aligned lateral heterostructure. A photodetector based on the lateral structure (BA 2 PbI 4 –BA 2 MAPb 2 I 7 ) shows larger photocurrent and higher on/off ratio (>10 2 ) than those of single material‐based devices (BA 2 PbI 4 , BA 2 MAPb 2 I 7 ). This method to fabricate 2D OIP lateral heterostructure suggests a simple way to synthesize 2D perovskite heterostructure and may open the possibility of 2D OIP perovskites to be integrated in emerging optoelectronic devices.