Effect Of Equivalent Elements Doping On The Thermoelectric Properties Of BiCuSeO

Thermoelectric material is a kind of functional material which enables direct conversion between thermal and electrical energy.In recent years,p-type BiCuSeO semiconductor thermoelectric material has attracted much attention because of its inherent low thermal conductivity.However,the conductivity of BiCuSeO thermoelectric materials is still low,which results in the restriction of its development.In order to solve this problem,the effect of Ho,Y,In doping and modulation doping on the properties of BiCuSeO-based thermoelectric materials were studied by means of equivalent element doping.The results are as follows:（1）The results of Ho-doped Bi_1-xHo_xCuSeO thermoelectric materials indicate that the carrier concentration increases monotonously and the mobility decreases monotonously with the increase of the doping content for all doped samples.With the increase of test temperature,the power factor and ZT value of doped samples begin to exceed that of the undoped sample,which is attributed tothe reduced difference of Sebeck coefficient.The maximum ZT value of 0.70 was obtained for Bi_0.90Ho_0.10CuSeO at 873 K,which is about 1.33 times that of the undoped sample（0.54）.（2）The results of Y-doped Bi_1-xY_xCuSeO thermoelectric materials indicate that the carrier concentration increases monotonously and the mobility decreases monotonously with the increase of the doping content for all other doped samples.Withthe increase of test temperature,exceptfor thedopedsample Bi_0.90Ho_0.10CuSeO,the power factor and ZT values of other Bi_1-x-x Y_xCuSeO gradually exceed those of undoped samples.The maximum ZT value of 0.63 was obtained for Bi_0.94Ho_0.06CuSeO at 873 K,which is 1.17 times of that of the undoped sample.（3）The results of In-doped Bi_1-xIn_xCuSeO thermoelectric materials indicate that the carrier concentration decreases monotonously and the mobility increases monotonously with the increase of the doping content for all doped samples.With the increase of test temperature,the doped samples with intermediate concentration（x=0.04 to 0.08）maintain higher not only Sebeck coefficient but electrical conductivity,which leads to a higher power factor and ZT value.The maximum ZT value of 0.68 was obtained for Bi_0.96Ho_0.04CuSeO at 873 K,which is about 1.26 times that of the undoped sample（0.54）.（4）The results of the synergistic effect of Ho doping and modulation structure show that with the increase of test temperature,the power factor of the modulated doped sample exceeds that of the uniformly doped sample,and the lattice thermal conductivity is also low.Consequently,the ZT value of Bi_0.90Ho_0.10CuSeO sample is higher than that of the uniformly doped sample at middle temperature.The maximum ZT value of 0.81 was obtained for Bi_0.96Ho_0.04CuSeO at 873 K,which is about 1.72times that of the undoped sample（0.54）.