Strain induced optoelectronic properties of two dimensional MnPSe₃/WS₂heterostructure

A series of first-principles calculations using Kohn-Sham density functional theory have been used to study MnPSe₃/WS₂heterostructures. The Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional has been chosen as the exchange-correlation potential because it gives energy gaps accurately. Five possible atomic stackings were considered to find most stable configuration for a heterostructure. Interestingly, all of the five configurations exhibit a maximum deviation in the binding energy equal to 47 meV which strongly indicates realization of the heterostructures. The calculated energy band gap (2.04 eV) of MnPSe₃/WS₂heterostructures is smaller (larger) than an isolated layer of MnPSe₃(WS₂). We simulated the role of (i) bi-axial strain, and (ii) interlayer spacing on the stability and electronic properties for pre-identified most stable configuration. Tuning of the energy band gap from 2.04 to 1.86 eV is achievable for case (i) while retaining stability of the system. However, in case (ii) band gaps can vary from 2.04 to 1.47 eV and the stability of the system decreases exponentially when following expansion or compression along thec-axis. Further, the effect of strain on valence and conduction band edges has been investigated in terms of band alignment with respect to vacuum level for cases (i) and (ii). To understand the optical features for the most stable configuration, absorption coefficient has been calculated using the frequency dependent real and imaginary parts of the dielectric functions. These calculations show an improved absorption capacity over the constituent layers. Our results may motivate experimentalists involved in developing efficient thin film heterostructure based optoelectronic devices.