Tunable anharmonicity versus high-performance thermoelectrics and permeation in multilayer (GaN)1–x (ZnO) x

Nonisovalent (GaN) 1− x (ZnO) x alloys are more technologically promising than their binary counterparts because of the abruptly reduced band gap. Unfortunately, the lack of two-dimensional (2D) configurations as well as complete stoichiometries hinders to further explore the thermal transport, thermoelectrics, and adsorption/permeation. We identify that multilayer (GaN) 1− x (ZnO) x stabilize as wurtzite-like Pm -(GaN) 3 (ZnO) 1 , Pmc 2 1 -(GaN) 1 (ZnO) 1 , P 3 m 1-(GaN) 1 (ZnO) 2 , and haeckelite C 2/ m -(GaN) 1 (ZnO) 3 via structural searches. P 3 m 1-(GaN) 1 (ZnO) 2 shares the excellent thermoelectrics with the figure of merit ZT as high as 3.08 at 900 K for the p-type doping due to the ultralow lattice thermal conductivity, which mainly arises from the strong anharmonicity by the interlayer asymmetrical charge distributions. The p – d coupling is prohibited from the group theory in C 2/ m -(GaN) 1 (ZnO) 3 , which thereby results in the anomalous band structure versus ZnO composition. To unveil the adsorption/permeation of H + , Na + , and OH − ions in AA -stacking configurations, the potential wells and barriers are explored from the Coulomb interaction and the ionic size. Our work is helpful in experimental fabrication of novel optoelectronic and thermoelectric devices by 2D (GaN) 1− x (ZnO) x alloys.