Electronic properties and band structure of Cu₂Sn_1−xCd_xSe₃. (a) Room temperature Hall carrier concentration and Hall carrier mobility of Cu₂Sn_1−xCd_xSe₃. Temperature dependence of (b) electrical conductivity and (c) Seebeck coefficient of Cu₂Sn_1−xCd_xSe₃. Carrier concentration dependence of (d) Seebeck coefficient and (e) carrier mobility of Cu₂Sn_1−xCd_xSe₃, with the solid curve representing the theoretical prediction by the SPB model. The effective mass of the matrix is embedded within this figure. (f) Relative deformation potential as a function of carrier concentration. DFT-calculated electronic band structures for (g) monoclinic, (h) cubic and (i) Cd-doped cubic Cu₂SnSe₃. The decreased energy difference (∆E) at the VBM is presented in these figures.