High Thermoelectric Performance in AgBiSe₂-Incorporated n-Type Bi₂Te_2.69Se_0.33Cl_0.03

Bismuth telluride-based (Bi₂Te₃) alloys have long been considered the best thermoelectric (TE) materials at room temperature. However, the n-type Bi₂Te₃ alloys always exhibit poor thermoelectric performance than their p-type counterpart, which severely limits the energy conversion efficiency of thermoelectric devices. Here, we demonstrate that incorporating AgBiSe₂ can concurrently regulate the electrical and thermal transport properties as well as improve the mechanical performance of n-type Bi₂Te_2.69Se_0.33Cl_0.03 for high thermoelectric performance. Among these, AgBiSe₂ effectively enhanced the Seebeck coefficients of n-type Bi₂Te_2.69Se_0.33Cl_0.03 due to the reduced carrier concentration and reduced the thermal conductivity of n-type Bi₂Te_2.69Se_0.33Cl_0.03 owing to the enhanced phonon scattering by AgBiSe₂ as well as its low thermal conductivity nature. Consequently, the simultaneous optimization of electrical and thermal transport properties enables us to achieve a maximum ZT of ∼1.21 (at ∼353 K) and an average ZT_ave of ∼1.07 (300-433 K) for 3.5 wt % AgBiSe₂-incorporated Bi₂Te_2.69Se_0.33Cl_0.03, which are ∼25.62 and ∼23.36% larger than those of Bi₂Te_2.69Se_0.33Cl_0.03, respectively. This work proves that the incorporation of AgBiSe₂ is an efficient way to improve the thermoelectric performance of bismuth telluride-based materials.