High thermoelectric performance of PNP abrupt heterostructures by independent regulation of the electrical conductivity and Seebeck coefficient

Improving thermoelectric conversion efficiency is a hotspot in the current field of thermoelectricity. In this work, a novel scheme for the P-I-Bi0.5Sb1.5Te3/N-Bi2Te2.97Se0.03/P-II-Bi0.5Sb1.5Te3 abrupt heterostructure vertical to temperature gradient is presented, resulting in theoretical results of high output power and conversion efficiency. Under the effect of temperature gradient, the hole concentrations in the PNP heterostructure change linearly and the build-in voltages also vary. As a result, the PNP heterostructure can possess the amplifying characteristic of the bipolar transistor, namely, the forward conduction occurs at the cold end in P-I-N junction and the reverse bias occurs at the hot end in N-P-II junction. The calculation results show that the optimal output power can reach 48.38 mW and conversion efficiency can reach 14.56% at delta T = 50 K. This work offers a new idea and method for the realization and application of high-performance thermoelectric materials.