Copper-Driven Engineering of Hot Carrier Extraction in Double Perovskites for Enhanced Radiation Detection Performance

Achieving a low limit of detection (LoD) and high sensitivity in lead-free X-ray detectors is critical for advancing their commercial viability. Doping strategies, widely used in conventional semiconductors, offer a promising approach to tailor material properties in halide perovskites. In this study, we systematically explore the impact of copper (Cu) doping on the radiation detection properties of lead-free double perovskite Cs2AgBiCl6 single crystals. An optimal Cu concentration of 1.3 wt % was identified, which markedly enhances X-ray detection performance. Cu incorporation introduces sub-bandgap states, leading to improved hot carrier extraction and suppressed radiative recombination, thereby facilitating more efficient charge carrier transport and enhancing overall detector sensitivity. The optimized Cu-doped Cs2AgBiCl6 single crystals demonstrated an ultralow LoD of 33 nGyair s–1 and improved sensitivity, attributed to enhanced hot carrier extraction and suppressed recombination, as confirmed by transient absorption spectroscopy. Additionally, the Cu-doped crystals were exposed to α particle radiation to evaluate their suitability for pulse-mode operation, indicating their potential for multifunctional radiation detection. This work offers a viable pathway for designing highly sensitive, lead-free radiation detectors suitable for commercial deployment.