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Issue 1, 2020
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A type-II GaSe/GeS heterobilayer with strain enhanced photovoltaic properties and external electric field effects

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Abstract

Constructing two dimensional (2D) van der Waals (vdW) heterostructures and understanding their electronic properties are pivotal for developing novel electronic devices. In this work, by using the first-principles calculations, we theoretically demonstrate that the 2D GaSe/GeS van der Waals (vdW) heterobilayer is a robust type-II band alignment semiconductor with a direct band gap of 1.8 eV. It exhibits a remarkable absorbance coefficient of ∼105 cm−1 from the UV to visible light region and a high carrier mobility with anisotropic character. The photoelectric conversion efficiency (PCE) shows a tremendous enhancement under external strain, and shows an efficiency of up to ∼16.8% at 2% compressive strain. Besides, we find that applying an external electric field can effectively modulate its band gap and band offset. Interestingly, a larger external electric field can induce nearly free electron (NFE) states around the conduction band minimum (CBM) in the GaSe/GeS heterobilayer, which leads to the band transition from a semiconductor to metallic status. These results indicate that 2D GaSe/GeS heterostructures will have widespread application prospects in future photovoltaic and optoelectric nanodevices.

Graphical abstract: A type-II GaSe/GeS heterobilayer with strain enhanced photovoltaic properties and external electric field effects

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Supplementary files

Article information


Submitted
25 Oct 2019
Accepted
29 Oct 2019
First published
30 Oct 2019

J. Mater. Chem. C, 2020,8, 89-97
Article type
Paper

A type-II GaSe/GeS heterobilayer with strain enhanced photovoltaic properties and external electric field effects

B. Zhou, S. Gong, K. Jiang, L. Xu, L. Shang, J. Zhang, Z. Hu and J. Chu, J. Mater. Chem. C, 2020, 8, 89
DOI: 10.1039/C9TC05840K

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