Fig. 2: Identification of temperature-driven polarization ripple in transverse pyroelectricity.

a Temperature profiles of a single conventional (stripe) and TPG devices. The upper and lower dashed lines refer to the maximum and half maximum temperatures of the TPG device. FWHM stands for the full width at half maximum of the temperature distribution. b, c Measured spatiotemporal temperatures (b) and polarization ripples (c) of TPG device. d The absolute current response for conventional (blue lines) and TPG (red lines) devices. The dashed line marks the maximum amplitude of absolute current for the conventional device. e The voltage response of a single conventional and TPG device. The time-differential voltage indicates the temperature-dependent voltage dynamics under the rising, saturation, falling, and decay stages. f The voltage varies with charge, and harvested energy (integration as shown in the shadow area) of a single conventional (stripe) and TPG devices, where W > W’ indicates the harvested energy of TPG is greater than that of conventional device. The dashed line masks zero voltage at thermal equilibrium, and the equivalent voltage relative to the cooling stage is negative, specifying the voltage consumption/decrease shown in Fig. 2e and Supplementary Fig. 7. The illumination intensity for measurement is 0.1 sun.