First-principle calculations of the electronic, elastic and thermoelectric properties of Ag doped CuGaTe2

• Ab-initio calculations for Ag doped CuGaTe2 were investigated.
• The electronic, stability, elastic and thermoelectric properties were studied.
• The Fermi level as a function of temperature was calculated.
• Ag doping increases carrier concentration and reduces lattice thermal conductivity.

To improve the performance of a thermoelectric material CuGaTe2, element Ag is doped to replace element Ga and we investigate the electronic structure, phase stability, elastic and thermoelectric properties of CuGa1−xAgxTe2 (x = 0, 0.25 and 0.5) via first-principles method. The phase stability of CuGa1−xAgxTe2 is discussed by analyzing the formation energy, cohesive energy and elastic constants. The calculated sound velocities decrease with the increase of Ag content, which is favorable for reducing the lattice thermal conductivity. The analysis of band structures shows that the replacement of Ga by Ag makes CuGaTe2 undergo a direct-indirect semiconductor transition. The Ag doping induces steep density of states in valence band edge, which is beneficial for increasing the carrier concentration and improving thermoelectric performance of CuGaTe2.