Cs ₂ AgBiBr ₆ /HfSe ₂ (0D/2D) nano-hetero interface for superior photoconduction via efficient charge separation

Abstract The optoelectronic phenomena of mixed-dimensional systems are captivating due to the presence of notably distinct electronic state spectra on either side of the interface. This work is designed to create an arrangement of fluorescent Cs ₂ AgBiBr ₆ nanocrystals (CABB NCs) on the surface of the HfSe ₂ nanosheet by a controlled self-assembly process. This resulted in a significant reduction in the fluorescence of the CABB NCs, which was thoroughly investigated through time-resolved photoluminescence experiments, density functional theory (DFT) calculations, and photoconductivity measurements. We have observed that such an interface renders good stability and excellent photo-responsivity of 0.117 A W ⁻¹ along with a detectivity of 2.58 × 10 ¹¹ Jones. Our findings suggest that the observed effects can be attributed to charge transfer facilitated by Type-II band alignment. The charge density distribution from DFT suggests a significant amount of charge is transferred from the HfSe ₂ surface to the CABB surface, which matches well with the experimental findings.