Studies on the Bi₂Te₃–Bi₂Se₃–Bi₂S₃system for mid-temperature thermoelectric energy conversion

TLDR

Bismuth telluride and its alloys are widely studied thermoelectric materials for cooling near room temperature. The study systematically investigates compounds in the Bi₂Te₃–Bi₂Se₃–Bi₂S₃ system. Samples were fabricated by high‑energy ball milling followed by hot pressing. Bi₂Te₂S₁ reaches a peak ZT of ~0.8 at 300 °C and Bi₂Se₁S₂ ~0.8 at 500 °C, showing that these n‑type materials can enable mid‑temperature power generation with segmented leg efficiencies up to 12.5 % (25 °C cold, 500 °C hot) that rival state‑of‑the‑art n‑type thermoelectrics.

Abstract

Bismuth telluride (Bi2Te3) and its alloys have been widely investigated as thermoelectric materials for cooling applications at around room temperature. We report a systematic study on many compounds in the Bi2Te3–Bi2Se3–Bi2S3 system. All the samples were fabricated by high energy ball milling followed by hot pressing. Among the investigated compounds, Bi2Te2S1 shows a peak ZT ∼0.8 at 300 °C and Bi2Se1S2 ∼0.8 at 500 °C. The results show that these compounds can be used for mid-temperature power generation applications. The leg efficiency of thermoelectric conversion for segmented elements based on these n-type materials could potentially reach 12.5% with a cold side at 25 °C and a hot side at 500 °C if appropriate p-type legs are paired, which could compete well with the state-of-the-art n-type materials within the same temperature range, including lead tellurides, lead selenides, lead sulfides, filled-skutterudites, and half Heuslers.