Photoelectric conversion beyond sunny days: all-weather carbon quantum dot solar cells

Abstract

Since the birth of solar cells, photovoltaic devices have experienced persistent breakthroughs in either crucial materials or technologies. However, the ability for power generation is only limited under sunlight illumination, i.e., all state-of-the-art solar cells can realize high-efficiency electricity outputs on sunny days. The power conversion efficiencies are zero at nights because of relatively low visible-light intensity. We present here a simple hydrothermal conversion from strawberry powders to carbon quantum dots (CQDs) for all-weather solar cell applications. Using green-emitting long persistence phosphors (LPPs) as light placeholders, the unabsorbed light ranging from visible to infrared light across CQD sensitized mesoscopic titanium dioxide (m-TiO₂) can be converted into green fluorescence, allowing for persistent CQD irradiation and therefore electricity generation at nights.