The effects of doping on the thermoelectric properties of two-dimensional Nowotny-Juza materials NaBeP and NaBeAs

Two-dimensional Nowotny-Juza compounds have great potential for thermoelectric applications due to their excellent mobility and good transport properties. In this study, the effects of Cu, Al-doped NaBeP and Li, P-doped NaBeAs on the stability and electronic properties of the materials are mainly investigated by first-principle calculations. The results show that the fundamental semiconductor nature of NaBeP and NaBeAs materials are not changed by doping. The electrical transport performance and thermal transport performance of different materials before and after doping have been systematically studied and analyzed in comparison to the Boltzmann transport theory and the deformation potential theory. The results showed that under the dual effects of improving the power factor and reducing the thermal conductivity of the material, NaBeP doped with Cu and Al ultimately optimized the thermoelectric properties of the material. Specifically, within the range of 400–800 K, when the carrier concentration is 1 × 1013 cm−2, the ZTave of the undoped material was 0.41, while the ZTave values of Cu- and Al-doped materials were 1.23 and 1.30, respectively. After doping NaBeAs with Li and P, the thermal conductivity of the material is reduced, thereby improving the thermoelectric performance. When the carrier concentration is 2 × 1012 cm−2, within the range of 400–800 K, the ZTave of the doped material is greater than 2, which are 2.37 and 2.34, respectively. These results indicate that two-dimensional NaBeP and NaBeAs can be effectively improved by means of doping and are promising for thermoelectric applications.