Highly Efficient Wideband Solar Energy Conversion Employing Singlet-Triplet Transitions

Abstract

Panchromatic sunlight energy harvesting is one of the key technologies to improve the performance of photovoltaics; however, while the near-infrared (NIR) light energy is easily converted into heat, energy conversion has proven difficult. In this study, we synthesize a new type of photosensitizer that exhibits singlettriplet transitions (spin inversion transition, S-T transition) in the NIR region. Using these sensitizers, we achieved highly efficient wideband photoenergy conversion, exceeding 1000 nm, with dye-sensitized solar cells. With only one type of small molecule, this was able to capture half of the photons in sunlight and convert them into electrical energy. This account describes the highly efficient panchromatic energy conversion, and solution-processed multijunction cells using perovskite solar cells.