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

Abstract All‐inorganic Cu‐based perovskite Cs x Cu y I 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 x Cu y I x + y perovskite films only have CsCu 2 I 3 phase owing to the epitaxy on CuI layer. And the thin film quality and optoelectronic properties of CsCu 2 I 3 are also improved. Then, metal–semiconductor–metal UV detectors based on CsCu 2 I 3 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 × 10 12 cm Hz 1/2 W −1 , which are 74 and 138 times larger than that of the device without the CuI buffer‐layer, respectively.