Strain-modulation of electronic and optical properties of two-dimensional GeTe/SnSe van der Waals heterostructure

•The bandgap and band alignment can be controlled.•The semiconductor-semimetal phase transition is observed.•The optical absorption of the heterostructure can be improved, and the power conversion efficiency can be improved. By first-principles method, the electronic and optical properties of stable GeTe/SnSe van der Waals heterostructure under strain have been investigated. By applying uniaxial and biaxial strain, the bandgap and band alignment of this heterostructure can be controlled, and semiconductor-metal phase transition is observed. By applying biaxial strain, the optical absorption of the heterostructure can be improved, and the power conversion efficiency can be improved from 13% to 19%. The easily controlled electronic properties and good optical properties make GeTe/SnSe van der Waals heterostructure to be a promising material in optoelectronic and solar energy conversion devices.