Highly Efficient Thermoelectric Microgenerators Using Nearly Room Temperature Pulsed Laser Deposition

Thermoelectric Bi₂Te₃ and Sb₂Te₃ thin films with high power factor were successfully obtained by pulsed laser deposition (PLD). Here, we demonstrate a well-controlled deposition of Bi₂Te₃/Sb₂Te₃ structures on glass substrates, through a shadow mask with micrometer-scale features. We establish an optimal growth temperature of 45 °C to attain compounds with suitable stoichiometric composition, as well as structural and electrical properties, to achieve high thermoelectric power factor. These films are produced without additional postannealing treatment or added gases. Indeed, crystalline films with Seebeck coefficients of 624 and -78 μV K^-1 are obtained for Sb₂Te₃ and Bi₂Te₃, respectively. Microgenerators consisting of four pairs of n-type Bi₂Te₃ and p-type Sb₂Te₃ legs connected in series generate a maximum voltage of 50 mV and a power density of around 120 μW cm^-2 for a temperature difference of 30 K across the hot and cold ends of the device. This low-temperature and simple PLD-deposited device represents an important step toward practical thermoelectric materials as well as efficient and compact microgenerators for low-temperature energy-harvesting applications.