Realizing ultrahigh room-temperature seebeck coefficient and thermoelectric properties in SnTe-based alloys through carrier modulation and band convergence

Seebeck coefficient is a crucial parameter in the field of thermoelectricity as it directly impacts the output power of thermoelectric devices. Intrinsic SnTe thermoelectrics exhibit excellent electrical conductivity but suffer from its low Seebeck coefficient, significantly impeding the advancement of the performance in both materials and devices. Herein, we focus on improving the Seebeck coefficient to favor the output voltage and power of SnTe thermoelectrics. Through a stepwise optimization strategy involving carrier concentration modulation and energy band convergence, we have substantially improved the performance of p-type SnTe thermoelectrics and enhanced the Seebeck coefficient across the entire temperature range. An ultrahigh Seebeck coefficient exceeding 103 μV K⁻¹ at ambient temperature, a highest ZT value of 1.3 at 823 K, and a maximum ZT_ave of ∼ 0.7 among 300–823 K were obtained in the Sn_0.82Mn_0.18Bi_0.03Te_0.91I_0.09 sample. Our study provides a universal strategy for advancing SnTe-based thermoelectrics and enhancing the power generation performance, which can be well broadened and implemented in various thermoelectric systems.