Green/Yellow-emitting Conjugated Heterocyclic Fluorophores for Luminescent Solar Concentrators

In recent years, direct conversion of sunlight into electricity by means of photovoltaics has been identified as a promising renewable solution for energy production. Nevertheless, large diffusion of PV panels is still limited by the elevated costs for materials and installations. For this reason, research on new technologies leading to cheaper PV devices is currently ongoing. In this context, sunlight concentration by Luminescent Solar Concentrators (LSC) appears a particularly promising concept. In our project, we developed compounds bearing the benzo[1,2-d:4,5-d']bisthiazole heterocyclic unit as organic fluorophores for LSC applications. The new compounds (CP03 and CP07) had a D-?-D structure, in which the central heterocyclic unit was decorated with triphenylamine donor groups to extend light absorption and emission wavelengths. The new compounds displayed light absorption in the 400-460 nm range and emission at 500-600 nm, with large Stokes shifts (92-149 nm) and good fluorescence quantum yields (0.42-0.68). CP07 was employed in the production of LSC devices, providing a remarkable optical efficiency value at the highest concentration tested (6.42% at 1.4%wt).