Bismuth-telluride-based alloys have been the state-of-art thermoelectric candidates near room temperature. However, sintered samples with higher ZT values in a wide temperature range are still urgently needed for further applications. Especially owing to the small band gap, the minority carriers are boosted at higher temperature and the thermoelectric properties are severely deteriorated. Here, we prepared p-type Bi_0.35Sb_1.65Te_3-xSe_x samples by hot pressing to enlarge the band gap and suppress the bipolar excitation. Although the carrier concentrations are slightly increased by the tiny Se alloying, the Seebeck coefficients above 400 K are significantly improved, and the bipolar and lattice contributions to thermal transport are obviously reduced. The x = 0.04 sample thus achieves an average value of 1.1 between 300 and 500 K, and the constructed thermoelectric device produces an output power density of 0.36 W cm⁻² and conversion efficiency of 5.24% at a temperature difference of 200 K. These results suggest that Se-doped Bi_0.35Sb_1.65Te₃ is a robust candidate for low-grade heat harvest near room temperature.

碲化铋基合金一直是接近室温的最先进的热电候选材料。然而，仍然迫切需要在较宽的温度范围内具有较高ZT值的烧结样品以进一步应用。特别是由于带隙小，少数载流子在较高温度下被提升，热电性能严重恶化。在这里，我们制备了p型 Bi _0.35 Sb _1.65 Te _{3- x} Se _x热压样品以扩大带隙并抑制双极激发。尽管微小的Se合金化使载流子浓度略有增加，但400 K以上的塞贝克系数显着提高，双极和晶格对热传输的贡献明显降低。因此，x  = 0.04 样品在 300 和 500 K 之间实现了 1.1 的平均值，并且构建的热电装置在 200 K 的温差下产生 0.36 W cm ^-2的输出功率密度和 5.24% 的转换效率。这些结果表明掺杂 Se 的 Bi _0.35 Sb _1.65 Te ₃是接近室温的低品位热收集的有力候选者。