Data from: Pressure-induced enhancement in the thermoelectric properties of mono- and bilayer SnSe2

The electronic structures of monolayer and bilayer SnSe2 under pressure were investigated by using first-principles calculations with van der Waals interactions included. For monolayer SnSe2, the variation of electronic structure under pressure is controlled by pressure-dependent lattice parameters. For bilayer SnSe2, the changes in electronic structure under pressure are dominated by intralayer and interlayer atomic interactions. The n-type thermoelectric properties of monolayer and bilayer SnSe2 under pressure were calculated on the basis of the semi-classical Boltzmann transport theory. It was found that the electrical conductivity of mono- and bilayer SnSe2 can be enhanced under pressure, and such dependence can be attributed to the pressure-induced changes of the Se-Sn antibonding states in conduction bands. Finally, the doping dependence of power factors of n-type monolayer and bilayer SnSe2 at three different pressures were estimated, and the results unveiled that thermoelectric performance of n-type mono- and bilayer SnSe2 can be improved by applying external pressure. This study benefits to understand the origins of the transport properties for monolayer and bilayer SnSe2 under pressure, and it offers valuable insight for designing high-performance thermoelectric few-layer SnSe2 through strain engineering induced by external pressure.本研究通过纳入范德华相互作用（van der Waals interactions）的第一性原理计算（first-principles calculations），探究了加压条件下单层与双层二硒化锡（SnSe₂）的电子结构。对于单层二硒化锡，其加压过程中电子结构的演化由压力依赖的晶格参数主导调控；而双层二硒化锡的电子结构变化则受层内与层间原子相互作用共同支配。本研究基于半经典玻尔兹曼输运理论（semi-classical Boltzmann transport theory），计算了加压条件下单层与双层二硒化锡的n型热电性能。研究发现，加压可提升单层与双层二硒化锡的电导率，该压力依赖特性可归因于压力诱导的导带中硒-锡反键态的变化。最后，本研究估算了三种不同压力下n型单层与双层二硒化锡功率因子的掺杂依赖关系，结果显示施加外压可有效提升n型单层及双层二硒化锡的热电性能。本研究有助于阐明加压条件下单层与双层二硒化锡输运性能的起源机制，并为通过外压诱导的应变工程设计高性能热电少层二硒化锡提供了极具价值的理论参考。