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.