posted on 2020-03-10, 18:01authored byWu-Xing Zhou, Dan Wu, Guofeng Xie, Ke-Qiu Chen, Gang Zhang
Using first-principles calculation and Boltzmann electron/phonon
transport theory, we present an accurate theoretical prediction of
thermoelectric properties of the α-Ag2S crystal,
a ductile inorganic semiconductor reported experimentally [Nat. Mater. 2018,17, 421].
The semiconductor α-Ag2S has ultralow thermal conductivity
associated with high anisotropy, which can be attributed to the complex
crystalline structure and weak bonding. The optimal values of the
Seebeck coefficient are 0.27 × 10–3 V/K for
n-type and 0.21 × 10–3 V/K for p-type α-Ag2S, respectively, which are comparable to those of many promising
thermoelectric materials. As a consequence, a maximum ZT value of 0.97/1.12 can be realized for p-type/n-type α-Ag2S at room temperature. More interestingly, the value of ZT can be further enhanced to 1.65 at room temperature by
applying 5% compressive strain. Moreover, we find that the electronic
thermal conductivity is a major factor limiting the ZT, which is several times the lattice thermal conductivity for n-type
α-Ag2S. Our work demonstrates the great advantage
of the α-Ag2S crystal as a ductile thermoelectric
material and sparks new routes to improve its figure of merit.