Pulsed laser deposition of lead-free Cs3Cu2Br5 thin films on GaN substrate for ultraviolet photodetector applications

Recently, intensive attention has been paid to the development of copper halide perovskites (CsCuX, X = I, Br, and Cl) due to their suitable band gaps, large light absorption, environmental stability, eco-friendliness, and low cost. Although CsCuBr possesses a much larger band gap than CsCuI perovskites, there have been few reports about CsCuBr due to its poor stability in the ambient environment. In this study, high-quality Cs3Cu2Br5 thin films with good stability were prepared on GaN substrates by pulse laser deposition (PLD) for the first time. The morphology, crystal structure, and photoelectric properties of the Cs3Cu2Br5 thin films were systematically studied. Moreover, a self-powered UV photodetector based on Cs3Cu2Br5/n-GaN heterojunction was fabricated. The heterojunction device exhibits two clear dominant responses in the UV region located at 270 nm and 360 nm, with the corresponding detectivities of 5.29 × 1011 cm·Hz1/2W−1 and 3.35 × 1011 cm·Hz1/2W−1. Besides, the photoresponse mechanism of the Cs3Cu2Br5/GaN photodetector has been studied by Anderson model. Our results suggest that lead-free Cs3Cu2Br5 thin films prepared by PLD could be a potential candidate for stable and environment-friendly optoelectronic devices, such as UV detectors and light emitting devices.