Energy Transfer in Nanodroplet‐Based Luminescent Solar Concentrators

Luminescent solar concentrators are promising devices for building-integrated photovoltaics, but their efficiency is limited by aggregation-induced quenching at high fluorophore concentrations and reabsorption losses during lightguide propagation. Here, we present a nanoconfinement strategy that addresses these challenges by embedding organic dyes within oil nanodroplets dispersed in polyvinyl alcohol coatings. The use of six commercial dyes demonstrated the versatility of this approach, which allows millimolar dye loadings while preventing aggregation, resulting in LSCs with excellent optical quality, low haze, and high optical efficiency. We further demonstrated Förster resonance energy transfer (FRET) systems by co-encapsulating donor-emitter pairs within single nanodroplets. Time-resolved spectroscopy confirmed efficient energy transfer, while measurements on LSCs with longer optical paths revealed that intradroplet FRET reduces distance-dependent losses. This sustainable and scalable approach, utilizing only commercial materials and simple processing techniques, offers a practical and cost-effective preparation of efficient and aesthetically suitable LSCs for building architecture.