Configuration design of BiFeO3 photovoltaic devices for self-powered electronic watch

Photovoltaic devices based on BiFeO3 (BFO) materials offer a direct approach for converting light into electricity. However, realizing high voltage in a single BFO photovoltaic device remains challenging. Here, we greatly boost the output voltage of single BFO photovoltaic devices by configuration design, including segmentation number and distance design, for electronic watches. Changes of photoexcited carrier generation and transport are responsible for the promoted output voltage. Based on the single BFO photovoltaic device which generates voltage as high as 1.71 V at the light intensity of 48.7 mW/cm(2), a BFO-capacitor-electronic watch has been established. After 240 s photo-charging by the BFO device, a 3300 mu F capacitor can sustain the watch continuously working for 1785 s and the operation time of the watch can be increased to 4258 s by replacing capacitors with homemade solid-state Li-ion batteries. This novel configuration design for single BFO photovoltaic devices holds promise for scavenging light energy for various wearable electronics by using ferroelectric photovoltaic devices.