Suppressed electron–phonon coupling in Ag-doped CsPbBr3 for high-performance photodetectors

Abstract

Charge transport in metal halide perovskites is strongly limited by electron–phonon coupling (EPC) and trap-assisted recombination, which together hinder carrier mobility and device efficiency. Therefore, precise control of EPC strength is crucial for realizing high-performance optoelectronic devices, such as photodetectors. Here, we demonstrate a strategy to overcome these limitations by suppressing Fröhlich electron–phonon coupling in CsPbBr3 nanocrystals through strategic Ag-doping. Low temperature photoluminescence data reveal a dramatic suppression of the Fröhlich interaction, with the EPC strength narrowing from 85.1 ± 8.2 to 45.3 ± 6.1 meV, accompanied by a reduced activation energy upon Ag incorporation. This suppression of phonon-mediated dissipation is further validated by ultrafast transient absorption studies, which reveals significantly prolonged ground-state bleach recovery and extended carrier lifetimes. Consequently, Ag-doped photodetectors exhibit a record detectivity of ∼8.4 × 1013 Jones, an on/off ratio of ∼107, and a fourfold enhancement in the responsivity (0.64 A/W). The near-unity photocurrent behavior with intensity (exponent of 0.98), along with emission behavior, confirms Ag-doping passivates defects and improves carrier extraction. These results establish a strong correlation between lattice engineering and macroscopic device physics, offering a scalable route to high-performance, phonon-managed perovskite optoelectronics.