Optoelectronic properties of type-II SePtTe/InS van der Waals heterojunction

Constructing van der Waals (vdW) heterojunctions via stacking different two-dimensional materials is an effective approach to obtain desirable properties. By using the first-principles calculation, we explore the vdW heterojunction based on the Janus structure of the 1T-PtTe2 for the potential application in the excitonic solar cell. The SePtTe/InS vdW heterojunction is found to be an appropriate material with direct bandgap, high carrier mobility, high optical absorption, and staggered type-II band alignment. The donor bandgap is 1.08 eV in the Heyd–Scuseria–Ernzerhof (HSE) level. The optoelectronic properties are effectively modulated by both external electric field and vertical strain because inducing the redistribution of charge density in the interlayer. Within the HSE hybrid density functional, the donor bandgap can be tunable up to 1.38 eV. The high power conversion efficiency is tunable to 24.91%, while the flux of absorbed photons keeps beyond 4.41 mA/cm2. Our results indicate the potential application of the SePtTe/InS heterojunction in solar cell utilization.