Luminescent solar concentrators based on thermally activated delayed fluorescence dyes

Thermally activated delayed fluorescence (TADF) dyes are third-generation light emitting materials. With impressive photophysical properties, TADF dyes are now widely recognized as successful emitters in organic light emitting diodes (OLEDs). However, their use in photovoltaic applications has not been realized. In this study, we for the first time present a TADF dye based luminescent solar concentrator device for efficient sunlight harvesting. We synthesized two carbazole dicyanobenzene (CDCB) derivative dyes and employed them in a bulk LSC device. Due to the charge transfer characteristics and twisted structures, TADF dyes help to achieve reduced reabsorption losses in the LSC. The photovoltaic measurements showed that the optical conversion efficiency (η_opt) and power conversion efficiency (η_PCE) of the champion device are 10.4% and 2.2%, respectively. Additionally, the superior resistance against photodegradation of TADF dyes facilitates their long-term use in LSCs. The results demonstrate that TADF dye-based LSCs provide a promising route for high-efficiency and low-cost solar energy generation.