Enhancement of Thermoelectric Performance of n-Type PbSe by Cr Doping with Optimized Carrier Concentration

Ti, V, Cr, Nb, and Mo are found to be effective at increasing the Seebeck coefficient and power factor of n-type PbSe at temperatures below 600 K. It is found that the higher Seebeck coefficients and power factors are due to higher Hall mobility approximate to 1000 cm(2) V-1 s(-1) at lower carrier concentration. A larger average ZT value (relevant for applications) can be obtained by an optimization of carrier concentration to approximate to 10(18)-10(19) cm(-3). Even though the highest room temperature power factor approximate to 3.3 x 10(-3) W m(-1) K-2 is found in 1 at% Mo-doped PbSe, the highest ZT is achieved in Cr-doped PbSe. Combined with the lower thermal conductivity, ZT is improved to approximate to 0.4 at room temperature and peak ZTs of approximate to 1.0 are observed at approximate to 573 K for Pb0.9925Cr0.0075Se and approximate to 673 K for Pb0.995Cr0.005Se. The calculated device efficiency of Pb0.995Cr0.005Se is as high as approximate to 12.5% with cold side 300 K and hot side 873 K, higher than those of all the n-type PbSe materials reported in the literature.