Spectroscopic Performance of CsPbBr 3 Perovskite γ‐Ray Detectors Despite Grain Boundaries

ABSTRACT The CsPbBr 3 perovskite has emerged as a promising material for next‐generation γ‐ray detection owing to its high stopping power, wide bandgap, and excellent charge‐transport properties. Unlike conventional semiconductors, in which grain boundaries (GBs) degrade response, we observed that CsPbBr 3 retains functional spectroscopic performance in their presence, demonstrating remarkable defect tolerance. We systematically investigate the impact of GBs on the performance and stability of CsPbBr 3 ‐based detectors. Detectors containing GBs exhibit measurable spectroscopic performance at room temperature, including resolved photopeaks at 59.5 keV ( 241 Am) and 122 keV ( 57 Co), along with hole mobility‐lifetime products ( µτ ) h on the order of ∼10 −4 cm 2 ·V −1 , highlighting the defect‐tolerant nature of CsPbBr 3 . Two‐photon excitation PL microscopy shows asymmetric carrier diffusion near GBs (under zero field bias), indicative of impeded charge transport, while transient waveform analysis captures field‐assisted detrapping that recovers charge collection on application‐relevant timescales. Our measurements indicate that device engineering choices, pixel placement/size, guard rings, field shaping, and electrode work‐function design can help drift paths and electric fields away from defects, and may reduce GB impacts.