Thin-film thermoelectric generator with ball lens for using near-infrared solar energy

A thin-film thermoelectric generator (TEG) with ball lenses which enable the visible light to pass through was designed and fabricated. When diameters of the ball lens and the pinhole were 6 mm and 200 μm, respectively, 76% of the visible light and 36% of the infrared light were transmissive to the TEG under the condition that the ball lens position from the device substrate was 0 μm. Thin-film TEGs were fabricated using lithography and thermoelectric thin film deposition processes. The thin film thermoelectric elements were formed on the glass substrate without removal by inserting the Cr buffer layers between the thermoelectric thin films and the substrate. The width of the elements were up to 10 μm greater than that of the designed one. The difference between the fabricated and the designed one was less than 10%, which is negligible value for the internal resistance of the TEGs.