Jump to main content
Jump to site search


Achieving a direct band gap and high power conversion efficiency in an SbI3/BiI3 type-II vdW heterostructure via interlayer compression and electric field application

Author affiliations

Abstract

Type-II van der Waals (vdW) heterostructures are considered as a class of competitive candidates of high-efficiency photovoltaic materials, due to their spontaneous electron–hole separation. However, most of the vdW heterostructures possess an indirect gap and a large band offset, which would lead to low photon-to-electron conversion efficiency. Taking an SbI3/BiI3 vdW heterostructure as an illustrative example, we propose interlayer compression and vertical electric field application as two effective strategies to modulate the electronic and photovoltaic properties of type-II vdW heterostructures. Our results reveal that a lattice-matched SbI3/BiI3 vdW heterostructure has an indirect band gap of 1.34 eV with the conduction band minimum (CBM) at the Γ point and the valence band maximum (VBM) between the Γ and M points. The power conversion efficiency (PCE) of an SbI3/BiI3-based excitonic solar cell (XSC) is predicted to be about 14.42%. When compressing the heterostructure along the vdW gap direction, the highest valence band state at the Γ point is lifted significantly and the VBM gradually approaches the Γ point, implying an indirect–direct gap transition. This interesting evolution can be attributed to the increasing k-dependent electronic hybridization of the pz orbitals of interlayer adjacent I atoms with a reduced interlayer distance. Moreover, the interlayer compression also enhances the PCE of the system monotonically. When applying a vertical electric field, the band alignment of the heterostructure undergoes a transition from type-II to type-I and then returns to type-II between 0.1 and 0.6 V Å−1. Meanwhile, the PCE of the SbI3/BiI3 XSC could be enhanced up to 21.63%. This work provides guidance for improving the electronic and photovoltaic properties of type-II vdW heterostructures.

Graphical abstract: Achieving a direct band gap and high power conversion efficiency in an SbI3/BiI3 type-II vdW heterostructure via interlayer compression and electric field application

Back to tab navigation

Supplementary files

Publication details

The article was received on 28 Nov 2018, accepted on 02 Jan 2019 and first published on 03 Jan 2019


Article type: Paper
DOI: 10.1039/C8CP07298A
Citation: Phys. Chem. Chem. Phys., 2019, Advance Article
  •   Request permissions

    Achieving a direct band gap and high power conversion efficiency in an SbI3/BiI3 type-II vdW heterostructure via interlayer compression and electric field application

    K. Lai, H. Li, Y. Xu, W. Zhang and J. Dai, Phys. Chem. Chem. Phys., 2019, Advance Article , DOI: 10.1039/C8CP07298A

Search articles by author

Spotlight

Advertisements