Bi₂Te₃-based thermoelectric (TE) materials have been demonstrated to be a potential candidate for mainly thermoelectric cooling/refrigeration applications. However, minority charge carriers excitation at high temperature reduces thermopower which restricts these materials for the use in power generation. In present work, substitution of Ni on Sb site in Bi_0.5Sb_1.5-xNi_xTe₃ (x = 0, 0.01, 0.04 and 0.08) actuates the system to supress the intrinsic excitation leading to shift in highest ZT to higher temperature regime. The Density functional theory (DFT) calculations and experimental results reveal that Ni in Bi_0.5Sb_1.5Te₃ provides the extra holes and slightly reduces the band gap E_g which enhances the σ of Ni-doped Bi_0.5Sb_1.5-xNi_xTe₃ samples and α at elevated temperature. Moreover, Ni-doping in Bi_0.5Sb_1.5Te₃ also reduces κ_L which is attributed to the phonon scattering due to mass fluctuations and microstructural features such as grain boundary and strain field domain observed from HRTEM investigation. These favourable condition leads to maximum ZT∼1.38 at 433K for Bi_0.5Sb_1.46Ni_0.04Te₃ and ZT_avg ∼1.1 between 300K and 503K. Interestingly the calculated theoretical TE conversion device efficiency η of Bi_0.5Sb_1.46Ni_0.04Te₃ (η∼5.5%) was achieved to be nearly twice than the efficiency of matrix Bi_0.5Sb_1.5Te₃ (η∼3%). Experimental electronic transport is well corroborated with theoretically estimated DFT results.

Bi ₂ Te ₃基热电(TE)材料已被证明是主要用于热电冷却/制冷应用的潜在候选材料。然而，少数电荷载流子在高温下的激发会降低热电势，这限制了这些材料在发电中的使用。在目前的工作中，在 Bi _0.5 Sb _1.5-x Ni _x Te ₃ (x = 0, 0.01, 0.04 和 0.08) 中取代 Sb 位点上的 Ni 会驱动系统抑制固有激发，从而导致最高 ZT 转移到更高温度状态. 密度泛函理论 (DFT) 计算和实验结果表明，Ni 在 Bi _0.5 Sb _1.5 Te ₃提供额外的孔并略微降低带隙 E _g，这增强了 Ni 掺杂的 Bi _0.5 Sb _1.5-x Ni _x Te ₃样品的σ和高温下的α。此外，在 Bi _0.5 Sb _1.5 Te _{3 中}掺杂 Ni还降低了 κ _L，这归因于由于质量波动和从 HRTEM 研究中观察到的晶界和应变场域等微观结构特征引起的声子散射。这些有利条件导致 Bi _0.5 Sb _1.46 Ni _0.04 Te ₃和 ZT _avg在 433K 时的最大 ZT∼1.38∼1.1 在 300K 和 503K 之间。有趣的是，计算出的 Bi _0.5 Sb _1.46 Ni _0.04 Te ₃ (η~5.5%) 的理论 TE 转换装置效率 η几乎是基体 Bi _0.5 Sb _1.5 Te ₃ (η~ ₃ %)效率的两倍。实验电子传输与理论上估计的 DFT 结果得到了很好的证实。