Substrate-Dependent Effects on the Growth of Methylammonium Lead Iodide Perovskites via Close Space Vapor Transport

摘要

Close space vapor transport is used to investigate PbI2 deposition and the reaction of PbI2 with CH3NH3I to form CH3NH3PbI3 (MAPI) on nanocrystalline (CdS) or amorphous (SnO2) electron transport layers (ETL). The crystallographic structure and surface morphology of PbI2 thin films and the resultant MAPI films after reaction have strong dependence on ETL substrates. Smoother morphology, stronger crystallographic orientation - (001) for PbI2 and (200) for MAPI films - and larger coherency length are observed for films grown on SnO2 ETL as compared to CdS. Solar cells fabricated on both types of ETL exhibit better cell performance for the MAPI absorbers that contain a small amount of residual PbI2. Despite crystallographic differences, solar cells made on both ETLs performed similarly.