Macroscopic and microscopic defect management in blue/green photodetectors for underwater wireless optical communication

Abstract

Hybrid organic–inorganic metal halide perovskites have attracted significant attention due to their excellent optical and electrical properties. However, intrinsic defects and poor carrier mobility remain two major concerns that limit the photoresponse of perovskite-based photodetectors. Here, a modified bromide-terminated Ti₃C₂ MXene nanoparticle (Br-MNP) decorating scheme is proposed to reduce macroscopic and microscopic defects and facilitates carrier transport. Specifically, Br-MNPs provide a Br-rich atmosphere to improve the crystallization process and compensate halide vacancies. Compared with the pristine film, the Br-MNP-mediated film exhibits an improved film morphology with enlarged vertical-oriented single grains, and possesses higher crystallinity with a reduced trap state density from 4.33 × 10¹⁵ cm⁻³ to 2.55 × 10¹⁵ cm⁻³. In addition, Br-MNPs acted as bridges between adjacent perovskite grains, which effectively accelerate carrier transport, leading to an enhanced carrier mobility of 0.210 cm² V⁻¹ s⁻¹. As a result, the Br-MNP mediated perovskite photodetector exhibits an improved photoresponse with a responsivity of 3.93 A W⁻¹, a noise level below 1.26 pA Hz^−1/2, and a short response time of less than 29.9 μs. An efficient underwater wireless optical communication system equipped with this device is also demonstrated, showing huge potential of such devices in practical applications.