Efficient broad-temperature Ettingshausen cooling unlocked in Bismuth

The discovery of the first thermoelectric effect in bismuth (Bi) by Thomas Seebeck in 1821 ushered in an era of research that, for over a century, has been dominated by narrow-gap semiconductors, typified by Bi2Te3 and Bi1-xSbx for room temperature and low temperatures, respectively. Unlike Peltier coolers, which rely on pairs of n- and p-type semiconductors for longitudinal current and heat flows, Ettingshausen ones leverage both electrons and holes in a single material to enable heat flow transverse to the current. However, high transverse thermoelectric performance has long been confined to narrow temperature windows of only tens of kelvin. Here, we propose a strategy that tailors the intrinsic band transport landscape to optimize semimetal transverse thermoelectrics over broad temperature ranges. Guided by this strategy, historical Bi is revealed as a broadly optimized transverse thermoelectric material, showing an average power factor exceeding 350 μW cm−1 K−2 and an average figure of merit of 1.25 over 200–300 K, outperforming typical longitudinal semiconductors. The resultant Ettingshausen cooler achieves a temperature drop of up to 84 K from 300 K and a specific cooling power density five times that of Peltier coolers under 8 T. This work might enlighten Ettingshausen cooling an alternative and competitive route for advancing thermoelectricity.