Enhanced Responsivity of CsCu₂I₃ Based UV Detector with CuI Buffer‐Layer Grown by Vacuum Thermal Evaporation

Abstract All‐inorganic Cu‐based perovskite Cs_xCu_yI_x+y thin films are deposited with vacuum thermal evaporation using CuI and CsI mixed powder with different proportion as evaporation sources. With CuI film as buffer‐layer, the as grown Cs_xCu_yI_x+y perovskite films only have CsCu₂I₃ phase owing to the epitaxy on CuI layer. And the thin film quality and optoelectronic properties of CsCu₂I₃ are also improved. Then, metal–semiconductor–metal UV detectors based on CsCu₂I₃ films with Au interdigital electrodes are fabricated and the enhancement of photoresponse performance is investigated in detail. The peak responsivity and specific detectivity of the detector are 49.22 mA W⁻¹ and 2.49 × 10¹² cm Hz^1/2 W⁻¹, which are 74 and 138 times larger than that of the device without the CuI buffer‐layer, respectively.