Ultrahighly-efficient and stable luminescent solar concentrators enabled by FRET-based carbon nanodots

Luminescent solar concentrators (LSCs) as an optical device to concentrate light from large areas illuminated by sunlight into small-area photovoltaic cells, can greatly reduce the cost of solar energy generation, thus showing promise in building-integrated photovoltaics. Here, we report the synthesis of a novel type of composite nanoparticle via the simple sol-gel method. Starting from hydroxyl-rich carbon nanodots (CDs), Rhodamine B (RhB) molecules were embedded into a silica matrix shell, forming a composite core-shell system, where the CDs represent the core and RhB embedded in SiO 2 are the shell of the final CDs/RhB@SiO 2 structure. These nanoparticles were successfully employed in high-performance LSC fabrication. The Förster resonant energy transfer (FRET) between the CDs and the dye was successfully exploited to improve the light absorption efficiency and power conversion efficiency ( η PCE ) of LSC devices. The solid-state photoluminescence quantum yield of the as-synthesized composite nanoparticles can reach ∼ 57 % due to the effective suppression of the aggregation-induced quenching. These fluorescent composite nanoparticles were used for fabricating LSC devices with an ultrahigh η PCE of ∼ 3.8 % for 5 × 5 cm 2 devices, thanks to the high loading of luminophores and effective FRET. • Synthesis of novel composite nanoparticle via the simple sol-gel method. • Core-shell nanoparticles composed of carbon dots (CDs) surrounded by Rhodamine B (RhB)-embedded silica matrix (CDs/RhB@SiO 2 ). • FRET between CDs and RhB dyes exploited. • Quantum yield of CDs/RhB@SiO 2 as high as 57 %. • High efficiency of the LSC devices (5 × 5 cm 2 area) ∼ 3.8 %.