High Thermoelectric Properties Induced in Double-Layer Black Arsenene via Decoupling Thermoelectric Coefficients

Motivated by the observation of mutual orthogonality between electrical conductivity and thermal conductivity on optimal transport direction and good stability in air, we investigate the thermoelectric property of few-layer black arsenene based on first-principles and Boltzmann transport theory. By incorporation of an anisotropy correction factor into the carrier relaxation time formula, the theoretical results successfully reproduce the experimental observations. The electronic line width of few-layer black arsenene is calculated to gain deeper insights into the band- and k-dependence of carrier lifetimes. Through the calculation of Grüneisen parameters and weighted scattering phase space, a layer-dependent phonon anharmonicity strength is discovered in few-layer black arsenene. Few-layer black arsenene is found to exhibit high thermoelectric performance under n-type doping, originating from its high electrical conductivity and low thermal conductivity. Interestingly, the double-layer system emerges a higher thermoelectric figure of merit ZT of 2.74 (0.41) among n-type (p-type) at 300 K compared to single-layer and triple-layer. Even though the effect of weak interlayer interaction on the Seebeck coefficient is very small, the layer-number-dependent decoupling of thermoelectric transport coefficients is responsible for the high ZT of double-layer black arsenene. This study highlights the promising potential of double-layer black arsenene for applications in nanoelectronics and thermoelectrics.