Luminescent Solar Concentrator Utilizing Energy Transfer Paired Aggregation-Induced Emissive Fluorophores

Recently, semitransparent luminescent solar concentrators (LSCs) have attracted considerable attention because they offer an easy and cost-effective route to harvest incident light. Various fluorophores including semiconducting quantum dots and organic dyes have been prepared and utilized for LSC fabrication. However, the narrow light absorption range, reabsorption losses, and limited photostability of the fluorophores still hinder the widespread use of LSCs under outdoor and indoor light conditions. Here, we rationally designed an LSC utilizing aggregation-induced emissive fluorophores (AIEgens) and an energy transfer (ET) strategy. We employ diketopyrrolopyrrole with triphenylamine moiety as a highly stable AIEgen that functions as an emissive ET acceptor in LSC; for a donor, we use tetraphenylethene containing triphenylamine moiety that shows good aggregation-induced emission features and excellent spectral overlap with the acceptor to yield an efficient ET process. A thin-film LSC device with an optimized donor:acceptor ratio (1:0.5) was fabricated. Under AM 1.5G solar spectrum, an LSC coupled with three side reflectors and a backside diffuser exhibits 18% optical conversion efficiency and a concentration factor of 1.18. Under indoor white LED illumination, the values were 27% and 1.68%, respectively. After exposed to intense UV radiations for 5 hours, the LSCs preserved 98% fluorescence which suggests their superior long-term photostability. Our results suggest that the combination of AIEgens and ET holds the potential for enhancing the efficiency of the device and extended stability of the fluorophores, two of the major requirements to allow industrial production and large-scale use of outdoor/indoor light harvesting LSCs.