Abstract
Two-dimensional (2D) materials have received substantial interest in recycling waste heat via the thermoelectric approach in recent years. In this article, we investigate the thermoelectric response of two novel 2D polymorphs of ZnO derived from the zinc-blende phase (ZnO(zb)) and 5-5 phase (ZnO(5-5)) for advance thermoelectric applications by first-principles. The thermoelectric behavior of these 2D polymorphs of ZnO has been evaluated from calculations of the thermoelectric power factor (PF) and figure-of-merit (zT) values. The p-type of doping results in the enhancement of PF for both monolayers of ZnO. The highest values of PF have been accordingly determined as 15.70 × 1010 W/mK2s at −2.40 eV for single-layered ZnO(zb) and 25.08 × 1010 W/mK2s at −1.81 eV for ZnO(5-5) monolayer. The recorded PF of single-layered ZnO(zb) has been found to decline slightly whereas a drastic increase in the PF of ZnO(5-5) monolayer has been recorded with an increase in temperature. Like PF, the zT values of these monolayers have been found larger for p-type doping of magnitude 0.583 and 0.977 respectively for ZnO(zb) and ZnO(5-5) monolayers. The predictions suggest the ZnO monolayers (ZnO(5-5) in particular) as promising candidates for advanced thermoelectric applications.
•Designing of novel 2D polymorphs of ZnO from zinc-blende and 5-5 type structures.•Calculations of the effective mass of charge carriers and their effect on the electrical conductivity.•Investigations of the Seebeck coefficients.•Investigations of power factors and zT values at different temperatures.