Two-Dimensional Heterostructure of MoS₂/BA₂PbI₄ 2D Ruddlesden–Popper Perovskite with an S Scheme Alignment for Solar Cells: A First-Principles Study

Abstract

Molybdenum disulfide (MoS 2 ) and a layered organic−inorganic Ruddlesden−Popper perovskite (RPP) show promising optoelectronics applications due to the splendid photoresponse. On consideration that each material has a specific favorable window for light excitation, it is naturally of interest to integrate both for broadening absorption and synergistic interlayer coupling. Herein, on the basis of density functional theory (DFT) computations, we investigate a two-dimensional (2D) MoS 2 / BA 2 PbI 4 RPP van der Waals (vdW) heterostructure by stacking monolayer MoS 2 and 2D BA 2 PbI 4 vertically. We find that the MoS 2 /BA 2 PbI 4 vdW heterostructure maintains a robust direct band gap with an enhanced light absorption that has a high solar to energy conversion efficiency. Moreover, the conduction band minimum (CBM) and the valence band maximum (VBM) are staggered and separately distributed within MoS 2 and BA 2 PbI 4 , respectively. Interestingly, the MoS 2 /BA 2 PbI 4 heterostructure shows a typical type II and S scheme interface arising from appropriate alignments of the Fermi levels and band edges between MoS 2 and BA 2 PbI 4 . Such a heterostructure enables the efficient separation of photoexcited electrons toward the MoS 2 side and holes via the BA 2 PbI 4 layer and thus a strong redox ability that is ideal for photocatalyst and solar cell applications.

Low-energy intralayer phonon assisted carrier recombination in Z-scheme van der Waals heterostructures for photocatalysis

“…5,6 One of the appealing aspects of these 2D heterolayers is potentially conning electrons and holes separately at different layers, allowing spatially restricted redox reactions. 7 Designing appropriate interfacial hybrid layers with an appropriate band alignment and prolonged carrier lifetimes, i.e. electronic injection, carrier relaxation, nonradiative recombination, etc., is the subject of ever increasing interest.…”

First-principles-driven catalyst design protocol of 2D/2D heterostructures for electro- and photocatalytic nitrogen reduction reaction

“…It has been reported that a stable heterostructure should exhibit a lattice mismatch, f , within 5%; 93 for example, 2D/2D Cs 3 Bi 2 Br 9 /CdS with f = 2.1%, 94 and 2D/2D MoS 2 /BA 2 PbI 4 with f = 2.34%. 81 Other computational works reported heterostructures with lattice mismatch beyond 5% such as 3D/2D Bi 2 S 3 /SnS 2 with f = 19.5% in the y -direction, 95 InP/InSb nanowire with f = 10.4% and the GaAs/InSb heterostructure with f = 14.6%. 96 These heterostructures were proposed to withstand relatively high strain because these monolayers are more flexible than those of bulk structures.…”

“…On the other hand, if the built-in electric field is in the opposite direction to that of the band alignment, the heterojunction is considered as a direct Z-scheme leading to higher electron and hole potentials at different sides of the heterostructure. For example, 2D/2D Cs 3 Bi 2 Br 9 /CdS 94 for nitrogen fixation, 2D/2D As/ZrS 2 (HfS 2 ) HSs, 98 TiO 2 /h-BN 160 and GeS/WS 2 156 for water splitting, 2D/2D MoS 2 /BA 2 PbI 4 95 for solar cells, and SnS/(CH 3 NH 3 ) 2 AgBiI 6 161 for CO 2 reduction. From the calculations, the effective mass of carriers for Cs 3 Bi 2 Br 9 /CdS vdWHs is reduced, thus accelerating the carrier transfer and decreasing the probability of carrier recombination.…”

Computational Design of a Strain-Induced 2D/2D g-C3N4/ZnO S-Scheme Heterostructured Photocatalyst for Water Splitting

“…34,35 The potential difference at the interface creates an internal electric field and band bending leading to the separation of photoexcited electrons and holes�electrons are transferred to the CB of the RP, while holes are transferred to the VB of the OP. 36 Such a charge-transfer process can retain the highest redox ability of the S-scheme heterojunction and promote its photocatalytic activity.…”

“…Recently, a novel concept of a step-scheme (S-scheme) heterojunction has been widely used to describe the effective charge transfer mechanism in heterostructured photocatalysts . An S-scheme heterojunction comprises two semiconductors: the oxidation photocatalyst (OP) and the reduction photocatalyst (RP) with staggered band structures. , The potential difference at the interface creates an internal electric field and band bending leading to the separation of photoexcited electrons and holeselectrons are transferred to the CB of the RP, while holes are transferred to the VB of the OP . Such a charge-transfer process can retain the highest redox ability of the S-scheme heterojunction and promote its photocatalytic activity.…”