WS2 monolayer integration in a FAPbI3-based heterostructure

Incorporating a monolayer of WS2 via interface engineering enhances the overall physical properties of a FAPbI3 perovskite based heterostructure. FAPbI3/WS2/TiO2/ITO and FAPbI3/TiO2/ITO heterostructures were analyzed by UV-Vis spectroscopy, x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The configuration with WS2 interlayer presents higher absorption in the visible region with a bandgap of ~1.45 eV. WS2 also enhances the deposition process of FAPbI3, resulting in the formation of pure photoactive ¿-phase without the non-photoactive ¿-phase or residual plumbates. The incorporation of the monolayer improves the crystalline structure of the FAPbI3, promoting a preferential growth in the [100] direction. The smooth surface of WS2 favors a homogeneous morphology and an increase in the grain size to ~4.5 ¿m, the largest reported for similar structures. Furthermore, the work function obtained lets us propose an enhanced an adequate energy band alignment between FAPbI3 and the n-type layers for the electron flux to the cathode. Conductivity and IV curves show a better performance with WS2. These findings strongly suggest that the interfacial coupling of FAPbI3/WS2 could be a promising candidate in photovoltaic applications. © 2024 Author(s).