Tunable Optoelectronic Properties of CsPbBr3 Perovskite Nanocrystals for Photodetectors Applications

Inorganic halide perovskite nanocrystals (NCs) have drawnconsiderableattention in recent years due to their improved stability, superiorphotophysical properties, and defect-tolerant nature, which allowsfor high carrier mobility and efficient charge transport in variousoptoelectronic devices. The bandgap and size of halide perovskitenanocrystals can be tuned through a variety of approaches, includingcation/anion exchange, ligand modification, and precursor concentrationadjustment. In this article, we investigate the effects of precursorconcentration on the structural, optical, and electronic propertiesof cesium lead bromide (CsPbBr3) nanocrystals. We havesynthesized & SIM;13-50 nm nanocrystals from four differentconcentrations of precursor solutions. It has been observed that theexcitonic absorption band increases with particle size as the precursorconcentration decreases. The steady state photoluminescence intensitydecreases due to a shorter carrier lifetime (in solution). We havefabricated photodetectors using four different-size samples and showthat the photoresponsivity increases with increasing particle size.The nanocrystals synthesized from the diluted precursor solution (0.005M) exhibits the highest detectivity of 2.84 x 10(9) jonesdue to their larger crystal size and fewer defect states, which resultsin a higher carrier diffusion length with reduced free carrier recombination.