Enhancement of Seebeck coefficient of mesoporous SrTiO3 with V-group elements V, Nb, and Ta substituted for Ti

The carrier concentration and effective mass of mesoporous SrTiO3 films were controlled by the substitution of Ti with V-group elements (V, Nb, and Ta) to enhance the thermoelectric properties. We calculated the effect of the substitution on the effective mass of SrTiO3 by analyzing its structural and electrical properties. When V was used as a substitute, the effective mass increased slightly due to a small change in the V-O bond distance. Moreover, when Nb and Ta were used as substitutes, the effective mass increased owing to an increase in the electronic density of states near the fermi level due to the increased bond length of Nb(or Ta)-O. Consequently, the use of Nb and Ta as substitutes in the SrTiO3 film induced an increase in the figure of merit value, which was due to increases in both the effective mass and carrier concentration.