Spanning the Solar Spectrum: Azopolymer Solar Thermal Fuels for Simultaneous UV and Visible Light Storage

A UV-sensitive azopolymer and a visiblelight-sensitive azopolymer are combined with a fluorescent dye and a filter to create a four-layer solar thermal cell with record efficiency gravimetric energy density. While most azopolymers discharge under visible irradiation, this device can use a true solar spectrum because fluorescent down-conversion enables storage of light that would otherwise cause discharging.