Regulating 3D Phase in Quasi-2D Perovskite Films for High-Performance and Stable Photodetectors

The charge transport in quasi-2D perovskites limits their applications despite the superior stability and optoelectronic properties. Herein, a novel strategy is proposed to enhance the charge transport by regulating 3D perovskite phase in quasi-2D perovskite films. The carbohydrazide (CBH) as an additive is introduced into (PEA)₂ MA₃ Pb₄ I₁₃ precursors, which slows down the crystallization process and improves the phase ratio and crystal quality of the 3D phase. This structure change results in a significant improvement in charge transport and extraction, leading to the device demonstrating an almost 100% internal quantum efficiency, a peak responsivity of 0.41 A W^-1 , and a detectivity of 1.31 × 10¹² Jones at 570 nm under 0 V bias. Furthermore, the air and moisture stability of (PEA)₂ MA₃ Pb₄ I₁₃ films is not deteriorated but gets significantly improved due to the better crystal quality and the passivation of defects by the residual CBH molecule. This work demonstrates a strategy for improving the charge transport properties of quasi-2D perovskites and also sheds light on solving the stability issue of 3D perovskite films via the proper passivation or additives, which will inspire the fast development of the perovskite community.