Luminescent solar concentrators based on energy transfer in polyurethane matrices

For a more sustainable energy transition, the use of solar energy has become of paramount importance, and Luminescent Solar Concentrators (LSC) represent an important solution for a smarter and more integrable photovoltaic. LSC are transparent slabs, generally made of glass, coated with a thin polymeric film containing a luminescent dye, that absorbs and re-emits a portion of the solar radiation. The emitted light is concentrated at the edges and converted into electricity by small photovoltaic cells. Luminescent perylene diimide and benzothiadiazole dyes have been considered because of the possibility to improve the LSC performance through a Förster Energy Transfer (FRET) process, leading to enhanced light-harvesting efficiency and cost effectiveness [1]. Also, their covalent incorporation into a polymeric backbone allows a homogeneous distribution in the matrix, hence allowing an efficient energy transfer, and it also offers a reduced molecular aggregation, thus, a reduced aggregation-caused quenching [2]. Here we present new LSC devices in which the donor, benzothiadiazole B1, and the acceptor, perylene diimide PDI1, are covalently incorporated into innovative polyurethanes. In particular, an LSC device realized with a polymer incorporating both B1 and PDI1 in a 1.00:0.15 ratio exhibited a photovoltaic efficiency of 0.63 % and an impressive external photon efficiency of 3.97 %. Therefore, covalent incorporation of B1 and PDI1 in a polyurethane matrix and the FRET process represents a step forward in the development of LSC. References: [1] B. Balaban, S. A. Carter, Journal of Luminescence 2014, 146, 256 – 262. [2] S. P. Russo, W. W. H. Wong, Journal of Material Chemistry C 2020, 8, 8953 – 8961.