Dopant-compensated Cs2AgBiBr6−xClx single crystals for photo-imaging and X-ray detection

Abstract

Inorganic double perovskites have been widely used in photodetection and X-ray detection due to their nontoxic composition, large atomic number, and simple crystal growth from solution. However, double perovskites have a lower formation energy, which introduces additional antisite defects, resulting in a higher trap-state density. Here we report dopant-compensated double perovskite Cs₂AgBiBr_6−xCl_x single crystals (SCs) based on solution processing, which reduces the trap state density of the single crystals, enabling enhanced photodetection and ray detection capabilities of the device at room temperature. The dopant-compensated Cs₂AgBiBr_5.933Cl_0.067 has a significantly improved mobility of 129 cm² V⁻¹ s⁻¹. By using Cl ion doping, the Cs₂AgBiBr_5.933Cl_0.067 SCs achieve excellent device performance in photodetection and X-ray detection, including a broad spectral response, a high responsivity of 60.8 mA W⁻¹, a fast response time of 8 μs/566 μs, a superior X-ray detection sensitivity of 714 μC Gy_air⁻¹ cm⁻², and a minimum dose rate as low as 36.48 nGy_air s⁻¹. Furthermore, the device exhibits high-fidelity photo-imaging at 5 V. All results demonstrate that an effective Cl ion doping strategy provides a great opportunity for developing functional detection devices.