Annihilation upconversion: harvesting the entire deep-red spectral range of the sun irradiation

Solar energy storage and conversion is a key technology for the future realization of a sustainable energy production worldwide. The utilization of low-energy photons by means of upconversion (UC) processes has the main advantage of the upconversion process and solar energy-harvesting devices being considered and optimized independently, without affecting the particular physical characteristics of the operating sunlight excited material or device architectures. The UC-device must function efficiently with noncoherent light excitation, under light intensities comparable with those obtainable from moderate concentrated sunlight (1 to 20 suns, AM1.5); such a low degree of concentration allows usage of Fresnel-type focusing systems. We report chemical synthesis and efficient functioning of a triplet–triplet annihilation upconversion-based device, harvesting the entire deep-red spectral range of the sun irradiation (Δλ∼142 nm) in a gap-free manner.