Optimizing thermoelectric properties of Bi₂Te₃ via Sb and Se Co-doping: experimental insights and finite elemental simulations using COMSOL

In this study, we investigated the impact of antimony (Sb) and selenium (Se) co-dopants on the thermoelectric properties of bismuth telluride (Bi₂Te₃). Our findings reveal that Sb doping significantly enhances the electrical conductivity of the material, increasing it by a factor of 2.83 for (Bi_0.98Sb_0.02)₂Te_2.7Se_0.3, primarily due to an increase in carrier concentration. The electrical resistivity of pristine Bi₂Te₃ at 300 K is 2.79 × 10⁻⁴ Ω·m, which decreases substantially to 0.006 × 10⁻⁴ Ω·m at 303 K with Sb doping at x = 0.02. Additionally, (Bi_0.96Sb_0.04)₂Te_2.7Se_0.3 composition achieves the highest power factor of 9.744 × 10⁻⁵ W/m·K² at 300 K, a 3-times improvement over the pristine Bi₂Te₃ (3.143 × 10⁻⁵ W/m·K²). The ZT value of Bi₂Te_2.7Se_0.3 is 3.5 times higher than that of the pristine material at 350 K. COMSOL simulations support the experimental findings, revealing a maximum temperature gradient of 35 °C (hot end: 20 °C, cold end: − 15 °C) for the (Bi_0.98Sb_0.02)₂Te_2.7Se_0.3 module with comparable p-type and n-type parameters. The increased temperature gradient in the COMSOL simulation correlates with the improved thermoelectric performance observed experimentally, indicating that co-doping Bi₂Te₃ with Sb and Se effectively enhances its thermoelectric properties.