Unlocking the Potential of Nanoribbon-Based Sb 2 S 3 /Sb 2 Se 3 van-der-Waals Heterostructure for Solar-Energy-Conversion and Optoelectronics Applications.

High-performance nanosized optoelectronic devices based on van der Waals (vdW) heterostructures have significant potential for use in a variety of applications. However, the investigation of nanoribbon-based vdW heterostructures are still mostly unexplored. In this study, based on first-principles calculations, we demonstrate that a Sb 2 S 3 /Sb 2 Se 3 vdW heterostructure, which is formed by isostructural nanoribbons of stibnite (Sb 2 S 3 ) and antimonselite (Sb 2 Se 3 ), possesses a direct band gap with a typical type-II band alignment, which is suitable for optoelectronics and solar energy conversion. Optical absorption spectra show broad profiles in the visible and UV ranges for all of the studied configurations, indicating their suitability for photodevices. Additionally, in 1D nanoribbons, we see sharp peaks corresponding to strongly bound excitons in a fashion similar to that of other quasi-1D systems. The Sb 2 S 3 /Sb 2 Se 3 heterostructure is predicted to exhibit a remarkable power conversion efficiency (PCE) of 28.2%, positioning it competitively alongside other extensively studied two-dimensional (2D) heterostructures.