Strategy to enhance the thermoelectric performance in Ti-doped Cu₃SbSe₄

P-type Cu₃SbSe₄, a thermoelectric material with inherently low lattice thermal conductivity, has garnered significant attention due to its promising thermal properties. Despite its intrinsically low lattice thermal conductivity, the thermoelectric performance (zT) of Cu₃SbSe₄ remains limited due to its low carrier concentration, which directly affects its electronic transport properties. Numerous investigations have focused on doping Cu₃SbSe₄ to increase its low carrier concentration, with several studies reporting successful improvements. However, a comprehensive understanding of electronic band structure modification due to doping remains elusive. Recently, a high zT (~ 0.59 at 623 K) in Ti-doped Cu₃SbSe₄ (Cu₃Sb_1–xTi_xSe₄) is reported. Using the Single Parabolic Band (SPB) model, the effect of Ti doping on the electronic band structure of Cu₃SbSe₄ is evaluated. Although the highest zT is obtained at Cu₃Sb_0.96Ti_0.04Se₄ (x = 0.04) experimentally, the best electronic band structure for high thermoelectric performance is obtained in the x = 0.03 sample (highest weighted mobility). Evidence supporting band convergence in the x = 0.03 sample is presented. Implementing appropriate nanostructuring to reduce the lattice thermal conductivity of the x = 0.03 sample to that of the x = 0.04 sample could theoretically elevate its zT to 0.76 at 623 K, representing a remarkable 29% enhancement. Concentrating nanostructuring efforts on a specific composition with the most promising electronic band structure for optimal thermoelectric performance is a pragmatic strategy for maximizing zT.