Investigations on Organic Push-Pull Dyes for Luminescent Solar Concentrator Applications

In recent years, the focus on luminescent solar concentrator (LSC) materials has been renewed thanks to their properties that support their integration into PV technologies in buildings and in the urban environment. In this work, three dyes bearing push-pull units and presenting anthracene (compound 1) or 2,1,3-benzothiadiazole (BTZ-P6t, compound 2, and TBTZ-P12t, compound 3) as the central chromophore module are investigated as luminophores for the LSCs based on polyacrylate. The optical and luminescence characterization of the dyes in solution and in polyacrylate panels has been carried out to examine the impact of medium polarity and stiffening on the photophysical behavior of the dyes. The photoluminescence quantum yield (PLQY), decay times, and radiative and nonradiative rate constants have been evaluated together with the overlap integral to rationalize the reabsorption phenomena. The photophysical parameters highlight that medium polarity and matrix stiffening have an impact on the photoluminescence properties. The evaluation of the photovoltaic performance, performed by placing an edge of dye panels in contact with a silicon PV device, shows that the panels act as LSCs. In particular, compound 3 exhibits the highest value of PLQY (81%), resulting in the highest value of PV light-to-energy conversion efficiencies (η_opt%, 2.8%). This study proposes a thorough and correlated examination of the photophysical characteristics of molecular systems when the media are switched from solution to acrylate panels in order to rationalize the photovoltaic performance of the prepared LSCs. Although the prepared dye-acrylate panels fall outside accepted standard dimensions for LSC size, this study is relevant to designing chromophore architecture for enhanced efficiencies for LSCs.