Dynamic optimization of the quantum-well (QW) width distribution in quasi-2D halide perovskite thin films is an effective approach for tuning the properties of photoelectric devices. Here, that the QWs width distribution in quasi-2D perovskite films can be controlled only by using hydroiodic acid (HI) as an additive is demonstrated. A uniform distribution of the colloidal particle size in the quasi-2D perovskite precursor solution is achieved through the formation of soluble iodoplumbate coordination complexes, PbI3 - from the reaction of HI with PbI2 , 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 PbI3 - 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 50 000, a responsivity of 0.96 A W-1 , and a detectivity of 5.7 × 1012 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.
Keywords: formation enthalpy; low-dimensional perovskite; narrow quantum wells; photodetectors; ultrafast transient absorption.
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