Regulation of Quantum Wells Width Distribution in Quasi-2D Perovskite Films for High-Performance Photodetectors.

Dynamic optimization of the quantum-well (QW) width distribution in quasi-two-dimensional (quasi-2D) halide perovskite thin films is an effective approach for tuning the properties of photoelectric devices. Here, we demonstrate that the QWs width distribution in quasi-2D perovskite films can be controlled only by using hydroiodic acid (HI) as an additive. A uniform distribution of the colloidal particle size in the quasi-2D perovskite precursor solution was achieved through the formation of soluble iodoplumbate coordination complexes, PbI 3 - from the reaction of HI with PbI 2 , resulting in an improved phase purity in the final film. Density functional theory calculations indicate that the ideal n value quasi-2D perovskite reaction pathway through the PbI 3 - complex has a lower enthalpy of formation than the random nucleation pathway without the HI additive. Benefiting from this merit, a high-quality quasi-2D perovskite film with optimized phase purity delivered a balanced carrier diffusion length and improved carrier mobility. The resultant photodetectors exhibited a light on/off ratio of 50000, a responsivity of 0.96 A W -1 , and a detectivity of 5.7 × 10 12 Jones at 532 nm. In addition, the state-of-the-art device maintained more than 80% of its initial photocurrent after 720 h of storage at 30% relative humidity. This article is protected by copyright. All rights reserved.