Highly-efficient thermoelectric pn-junction device based on bismuth telluride (Bi2Te3) and molybdenum disulfide (MoS2) thin films fabricated by RF magnetron sputtering technique

Layered structure bismuth telluride and molybdenum disulfide thin films were successfully deposited on different substrates using radio-frequency magnetron sputtering technique. The structural, morphological, and thermoelectric transport properties of bismuth telluride and molybdenum disulfide thin films have been investigated systematically to fabricate high-efficient thermal energy harvesting thermoelectric device. The magnitude of the Seebeck coefficient of bismuth telluride thin films decreases with increase in film thickness. Bismuth telluride grown at 350 degrees C for 10 min, which is approximately 120 nm, displays a maximum Seebeck coefficient of -126 mu VK-1 at 435 K. The performance shows strong temperature dependence when the films were deposited at 300 degrees C, 350 degrees C, and 400 degrees C. The power factor increases from 0.91 x 10(-3) W/mK(2) at 300 K to about 1.4 x 10(-3) W/mK(2) at 350 K. Molybdenum disulfide films show the positive Seebeck coefficient values and their Seebeck coefficient increases with film thickness. The AFM images of bismuth telluride thin films display a root-mean-square (rms) roughness of 32.3 nm and molybdenum disulfide thin films show an rms roughness of 6.99 nm when both films were deposited at 350 degrees C. The open-circuit voltage of the pn-junction thermoelectric generator (TEG) device increases with increase in Delta T to about 130 mV at Delta T = 120 degrees C. We have demonstrated a highly efficient pn-junction TEG device for waste heat recovery applications. Published by AIP Publishing.