Versatile Single-Layer Sodium Phosphidostannate(II): Strain-Tunable Electronic Structure, Excellent Mechanical Flexibility, and an Ideal Gap for Photovoltaics.
Density functional theory (DFT) calculations were performed to study the structural, mechanical, electrical, optical properties, and strain effects in single-layer sodium phosphidostannate(II) (NaSnP). We find the exfoliation of single-layer NaSnP from bulk form is highly feasible because the cleavage energy is comparable to graphite and MoS2. In addition, the breaking strain of the NaSnP monolayer is comparable to other widely studied 2D materials, indicating excellent mechanical flexibility of 2D NaSnP. Using the hybrid functional method, the calculated band gap of single-layer NaSnP is close to the ideal band gap of solar cell materials (1.5 eV), demonstrating great potential in future photovoltaic application. Furthermore, strain effect study shows that a moderate compression (2%) can trigger indirect-to-direct gap transition, which would enhance the ability of light absorption for the NaSnP monolayer. With sufficient compression (8%), the single-layer NaSnP can be tuned from semiconductor to metal, suggesting great applications in nanoelectronic devices based on strain engineering techniques.
†School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Gardens Point Campus, Queensland 4001, Brisbane, Australia.
Yalong
Y
Jiao
†School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Gardens Point Campus, Queensland 4001, Brisbane, Australia.
Fengxian
F
Ma
†School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Gardens Point Campus, Queensland 4001, Brisbane, Australia.
Guoping
G
Gao
†School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Gardens Point Campus, Queensland 4001, Brisbane, Australia.
John
J
Bell
‡Bremen Center for Computational Materials Science, University of Bremen, Am Falturm 1, 28359 Bremen, Germany.
Thomas
T
Frauenheim
†School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Gardens Point Campus, Queensland 4001, Brisbane, Australia.
Aijun
A
Du
density functional theory; mechanical exfoliation; optical properties; strain effects; two-dimensional materials