Structural features and thermoelectric performance of chalcopyrite Cu(In, Ga)Te2 system by isoelectronic substitution

In this paper, a series of CuIn1-xGaxTe2 samples were prepared by vacuum melting combined with the spark plasma sintering process based on the initial stoichiometric ratios of 1: 1-x: x: 2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0). Crystal results indicate that all Cu(In, Ga)Te2 system samples are the chalcopyrite structure with space group I42d. Thermal analysis results show that all the samples have excellent reproducibility and thermal stability. EPMA data indicates that Ga tended to replace In site instead of Cu or Te. Meanwhile, the roomtemperature carrier concentration of all p-type samples varies from 0.30 x 1019 to 1.25 x 1019cm- 3, since carrier mobility changes from 15.16 to 69.27 cm2 V-1 s-1. Ultimately, the significantly reduced total thermal conductivity is observed in the Ga-doped samples, and the maximum ZT value of 0.80 is obtained at 773 K for the CuIn0.8Ga0.2Te2 sample due to the lower thermal conductivity.