Low‐Temperature Crystallized and Flexible 1D/3D Perovskite Heterostructure with Robust Flexibility and High EQE‐Bandwidth Product

Abstract

AbstractAll‐inorganic perovskite cesium lead triiodide (CsPbI3) has attracted much attention among the perovskite family due to its excellent optoelectronic properties and chemical stability. However, the high‐temperature crystallization process makes CsPbI3 less compatible with commercially flexible substrates, limiting its application into flexible optoelectronics. Here, a cation of 1‐(3‐aminopropyl)‐2pyrrolidinone (APP) is reported that can form 1D (APP)PbI3 perovskite as templates, and significantly reduce the CsPbI3 black‐phase transition energy with a low annealing temperature of 75 °C, which further enables a flexible (APP)PbI3/γ‐CsPbI3 (1D/3D) heterostructure photodetector on ITO/PET substrate. A high external quantum efficiency (EQE) greater than 2377% is observed along the orientated 1D/3D heterostructure. The high gain and low noise result in a high specific detectivity (D*) over 1012 Jones under −0.6 V low bias. The optimized device structure brings a high EQE × bandwidth product of 119 kHz under a low driving bias. Due to the high toughness of orientated APP+ ions and the face‐connected [PbI3]− chains structure as a strong energy absorber, the flexible photodetector also shows excellent phase stability and impressive flexibility, remaining >90% initial responsivity after over 20 000 times bending with potential flexible imaging application in harsh environments.