Figure 5.

Outdoor demonstration of a large-scale prototype module. (a) Photograph of the thermogalvanic cell prototype with an active area of 100 cm². The device is fixed by an aluminum foil-covered foam box to decrease thermal losses and avoid sunlight absorption around the device. (b) Maximum current-voltage and power-voltage curves of the device at daytime and nighttime, respectively. (c) Temperature (upper) of the top electrode and bottom electrode and open-circuit voltage (lower) versus time. The upper and lower insets show the measured natural solar intensity and ambient relative humidity, respectively. The device operated continuously from 8:00 (October 31, 2018) to 8:00 (November 1, 2018) at the Wuhan National Laboratory for Optoelectronics (WNLO), China (30°30′49′′ N, 114°25′13′′ E, 35 m altitude).