Simulation Evidence of Hexagonal-to-Tetragonal ZnSe Structure Transition : A Monolayer Material with a Wide-Range Tunable Direct Bandgap

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Detail(s)

Original languageEnglish
Article number1500290
Journal / PublicationAdvanced Science
Volume2
Issue number12
Publication statusPublished - 1 Dec 2015
Externally publishedYes

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Abstract

2D material with tunable direct bandgap in the intermediate region (i.e., ≈2–3 eV) is key to the achievement of high efficiency in visible-light optical devices. Herein, a simulation evidence of structure transition of monolayer ZnSe from the experimental pseudohexagonal structure to the tetragonal structure (t-ZnSe) under lateral pressure is shown, suggesting a possible fabrication route to achieve the t-ZnSe monolayer. The as-produced t-ZnSe monolayer exhibits highly tunable bandgap under the biaxial strains, allowing strain engineering of t-ZnSe's bandgap over a wide range of 2–3 eV. Importantly, even under the biaxial strain up to 7%, the t-ZnSe monolayer still keeps its direct-gap property in the desirable range of 2.40–3.17 eV (corresponding to wavelength of green light to ultraviolet). The wide-range tunability of direct bandgap appears to be a unique property of the t-ZnSe monolayer, suggesting its potential application as a light-emitting 2D material in red–green–blue light emission diodes or as complementary light-absorption material in the blue–yellow region for multijunction solar cells. The straddling of the band edge of the t-ZnSe monolayer over the redox potential of water splitting reaction also points to its plausible application for visible-light-driven water splitting.

Research Area(s)

  • light emitting and absorption, strain engineering, tetragonal ZnSe monolayer, wide-range tunable direct bandgap

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