Photodetectors with High Responsivity by Thickness Tunable Mixed Halide Perovskite Nanosheets

Chemical transformation of typically nonlayered phases into two-dimensional structures remains a formidable task. Among the thickness tunable CsPbX3 (X = Br, Br/I, I) nanosheets (NSs), CsPbBr1.5I1.5 NSs with a thickness of similar to 4.9 nm have structural stability superior to similar to 6.8 nm CsPbI3 NSs and better hole mobility than similar to 3.7 nm CsPbBr3 NSs. Moving beyond the much-explored CsPbBr3 photodetectors, we demonstrate a sharp improvement of the photodetection of CsPbBr1.5I1.5 NS devices by thickening the NSs to similar to 6.1 nm through combining 8-carbon and 18-carbon ligand surfactants. Thereby, the responsivity increases up to one of the highest values of 3313 A W-1 at 1.5 V (and 3946 A W-1 at 2 V) with detectivity of 1.6 x 10(11) Jones at 1.5 V, due to the increase in carrier mobility up to 7.9 X 10(-4) cm(2) V-1 s(-1). The better device performance of the NSs than 8.6-13.9 nm nanocubes (NCs) is due to their planarity which facilitates in-plane mobilization of the charge carriers.

Automated summary

In this study, CsPbBr1.5I1.5 nanosheets were thickened to 6.1 nm by combining different ligand surfactants, leading to a significant improvement in device performance with increased responsivity and detectivity. The planarity of the nanosheets facilitated in-plane mobilization of charge carriers, resulting in better performance compared to nanocubes of 8.6-13.9 nm.