Interfacial Interactions in Monolayer and Few‐Layer SnS/CH₃NH₃PbI₃ Perovskite van der Waals Heterostructures and Their Effects on Electronic and Optical Properties

Abstract

A high light-absorption coefficient and long-range hot-carrier transport of hybrid organic-inorganic perovskites give huge potential to their composites in solar energy conversion and environmental protection. Understanding interfacial interactions and their effects are paramount for designing perovskite-based heterostructures with desirable properties. Herein, we systematically investigated the interfacial interactions in monolayer and few-layer SnS/CH NH PbI heterostructures and their effects on the electronic and optical properties of these structures by density functional theory. It was found that the interfacial interactions in SnS/CH NH PbI heterostructures were van der Waals (vdW) interactions, and they were found to be insensitive to the layer number of 2D SnS sheets. Interestingly, although their band gap decreased upon increasing the layer number of SnS, the near-gap electronic states and optical absorption spectra of these heterostructures were found to be strikingly similar. This feature was determined to be critical for the design of 2D layered SnS-based heterostructures. Strong absorption in the ultraviolet and visible-light regions, type II staggered band alignment at the interface, and few-layer SnS as an active co-catalyst make 2D SnS/CH NH PbI heterostructures promising candidates for photocatalysis, photodetectors, and solar energy harvesting and conversion. These results provide first insight into the nature of interfacial interactions and are useful for designing hybrid organic-inorganic perovskite-based devices with novel properties.

Wide channel broadband CH3NH3PbI3/SnS hybrid photodetector: breaking the limit of bandgap energy operation

“…2f ]. 19 The photo-generated holes within the CH 3 NH 3 PbI 3 are transferred to the SnS due to type-II heterojunction, resulting in the improved overall performances.…”

“…One can see that the photocurrent decreases from UV to visible range and responds even at 850 nm. 19 However, it has been predicted from the density functional theory that the band gap of the hybrid CH 3 NH 3 PbI 3 /SnS is reduced to NIR range, which in turn make it very suitable to design broadband photodetector. The present device may offer the possibility to design an advanced broad band photodetector over a large area.…”

“…Recently, it is reported that the layered SnS and CH 3 NH 3 PbI 3 forms a van der Waals heterostructure, which was predicted as a superior junction for photodetection. 19 The integration of these two materials, therefore, offers opportunities to understand unique charge transfer mechanisms and light matter interactions for the application of photodetector, even below the individual band gaps.…”

Improving the stability of perovskite by covering graphene on FAPbI 3 surface

“…It has been proved that theoretical simulation can offer powerful insight into the fundamental understanding of structures and properties of interfaces. DFT calculations conducted by Huang et al 43 indicated that staggered band alignment formed at the interface of SnS/MAPbI 3 is beneficial for electron–hole separation. Theoretical calculations of Chang et al 32 predicted that the MAPbI 3 /SnO 2 interface with PbI termination possesses more excellent and stable properties than those of MAPbI 3 /SnO 2 interfaces with other configurations and MAPbI 3 /TiO 2 interfaces, and their experimental observations of current density ( J sc ), open circuit voltage ( V oc ), fill factor (FF), and PCE verified their theoretical prediction.…”

Theoretical Insights into Perovskite Compounds MAPb1−αXαI3−βYβ (X = Ge, Sn; Y = Cl, Br): An Exploration for Superior Optical Performance

“…Recently, the perovskite-based solar cell with the efficiency of 23.2% is successfully fabricated by virtue of fluorine-terminated holetransport materials instead of common spiro-MeOTAD. 20 Simultaneously, the stability of the resultant device is dramatically enhanced because its initial performance still retained 95% after 500 h. So far, there are two major strategies of improving the performance of the PSCs, one is forming heterostructure by selecting a suitable coating layer such as SnS/MAPbI 3 , 21,22 which has been confirmed to have superior performance than the pure MAPbI 3 ; the other is through ion doping. First, the band gap can be effectively tuned by means of organic cation doping, although they almost have little contribution to the electronic states at the band-gap edges.…”