Cs₃Cu₂I₅ Single Crystal for Efficient Direct X‐Ray Detection

Abstract Low‐dimensional copper‐based halide single crystals are considered excellent scintillators for indirect X‐ray detection, but their potential in direct X‐ray detection has not been investigated. Herein, high‐quality pure Cs 3 Cu 2 I 5 and Li‐doped Cs 3 Cu 2 I 5 :Li single crystals are grown by the Bridgman method. The Li + dopant enhances the photoelectric properties of the Cs 3 Cu 2 I 5 single crystal by extending the carrier lifetime, improving the carrier mobility from 6.49 to 9.52 cm 2 V −1 s −1 , and increasing the mobility‐lifetime (µ τ ) product from 1.4 × 10 −4 to 2.9 × 10 −4 cm 2 V −1 . The sensitive direct X‐ray detector with a vertical device configuration of Au/Cs 3 Cu 2 I 5 :Li single crystal/PCBM/Au is fabricated and demonstrated to have a high sensitivity of 831.1 µC Gy air −1 cm −2 and low detection limit of 34.8 nGy air s −1 . Furthermore, the detector shows negligible baseline current drift and excellent stability upon X‐ray radiation.