From Lead-Free Halide Perovskites to High-Performance Photodetectors: A Review of the State of the Art in Materials Engineering Strategies and Innovative Approaches

Abstract

Lead-free halide perovskite photodetectors (PDs) based on bismuth (Bi), antimony (Sb), tin (Sn), and copper (Cu) have garnered considerable interest as an alternative to conventional lead-based perovskite PDs because of their favorable optoelectronic properties, tunable band gaps, and light absorption characteristics. Nevertheless, such PDs face challenges related to charge transport, defect density, stability, and range of detection that hinder their overall photodetection performance. The present review provides insights into various material engineering approaches, including interfacial, morphological, compositional, and heterojunction engineering approaches, aimed at overcoming these challenges. In the case of interfacial engineering, single-sided, double-sided, and defect passivation strategies were described in this review. Morphological engineering approaches, including single-crystal growth techniques, chemical vapor deposition (CVD), nanoporous structures, and space-confined growth techniques, were also described. Mixed-halide substitution and metal ion doping are prominent compositional engineering strategies that have been highlighted, along with the optimal tuning of heterojunctions. This review also provided insights into the various photodetection mechanisms of lead-free halide perovskite PDs, including staggered type-II band alignment, gradient band alignment, negative photoconductivity, self-trapped excitons (STEs), and self-trapped polarons (STPs). Finally, the application of these PDs in imaging and optical communication along with future research perspectives were discussed.