Interfacial Charge Transfer Induced Enhanced Near-Infrared Photoluminescence and Enhanced Visible Photodetection in Two-Dimensional/Zero-Dimensional Bi2Se3/CsPbBr2I Heterojunctions with Type-I Band Alignment

Unraveling the charge transfer across a heterointerface is crucial for cutting-edge optoelectronic applications, including photodetectors, solar photo-voltaics, light-emitting diodes, and so on. The incorporation of perovskite nanocrystals (NCs) into optoelectronics is limited primarily because of the presence of grain boundaries, carrier trapping, and ion migration, which restricts charge/energy transfer. Combining perovskite NCs with two-dimensional (2D) materials is a powerful approach to enhance energy harvesting and transport at the 0D-2D heterointerface. A simple sonication method was adopted to integrate zerodimensional (0D) mixed halide perovskite CsPbBr2I NCs and topological 2D Bi2Se3 nanosheets (NSs) to realize a nanohybrid system. A series of optical signatures such as Raman shift, quenching of photoluminescence (PL), and shortened fluorescence lifetime in the nanohybrid clearly substantiate the interfacial charge transfer dynamics. Cyclic voltammetry and Kelvin probe force microscopy analysis and the optical studies established the type-I band alignment between perovskite NCs and Bi2Se3 NSs. The charge transfer dynamics of the nanohybrid was confirmed from the dramatic quenching of the PL intensity of CsPbBr2I NCs and an associated increase in the NIR PL as well as visible PL intensities of the Bi2Se3 NSs owing to increased carrier density caused by charge transfer. Furthermore, improved photoresponse performance of the hybrid system demonstrates the role of interfacial carrier transfer in 2D-0D nanohybrids, suppressing the radiative recombination in the light-harvesting perovskite NCs. The nanohybrid-based photo detector exhibits a high spectral responsivity of 14.4 A/W, a spectral detectivity of 0.4 x 10(12) Jones, and a fast growth/decay time of 82 mu s/24 mu s. These results will stimulate further exploration of topological 2D materials/halide perovskite-based novel hybrid functional devices for photodetection, light-harvesting, and light-emitting applications.