Lead‐Free Cs₃Sb₂Br₉ Single Crystals for High Performance Narrowband Photodetector

Abstract Lead‐free single crystal perovskite materials exhibit impressive characteristics, such as high carrier mobility, low trap density, and long diffusion length. Herein, the high‐performance blue light photodetectors are reported based on lead‐free all‐inorganic Cs₃Sb₂Br₉ perovskite single crystals. These millimeter‐sized Cs₃Sb₂Br₉ single crystals have small thermal activation energy of 56.8 meV estimated by temperature‐dependent photoluminescence study. There is no obvious structural phase transition of the as‐obtained Cs₃Sb₂Br₉ single crystals since no Raman peak shift is observed with temperature increasing from 80 to 300 K. The as‐constructed high quality Cs₃Sb₂Br₉ single crystals photodetectors have an excellent performance of a responsivity of 2.29 A W⁻¹, a sharp detectivity of 3.77 × 10¹² Jones, and an external quantum efficiency (EQE) peak of 1.8 × 10³%. Moreover, the photodetectors exhibit a fast response time (<0.2 ms) and the full width at half maximum (FWHM) of the sharp EQE peak is as narrow as 15 nm. This work provides a promising strategy in the design of lead‐free, stable, and high‐performance perovskites for photodetector devices.