Thiazolo[5,4-d]thiazole-based organic sensitizers with improved spectral properties for application in greenhouse-integrated dye-sensitized solar cells

Organic photosensitizers especially designed for producing semitransparent dye-sensitized solar cells (DSSCs) for greenhouse integration were prepared by introduction of different heterocyclic moieties into the thiazolo[5,4-d]thiazole molecular scaffold. The aim was that of improving their light absorption capability in the green part of the visible spectrum while maintaining a good transparency in the blue and red regions, where the photosynthetic response is maximized. A short and efficient synthetic approach, featuring two consecutive C–H activation reactions in a one-pot procedure as key steps, was used. Based on their spectroscopic and electrochemical characterization, two of the dyes prepared appeared especially suitable for greenhouse-integrated photovoltaics. The corresponding semitransparent DSSCs yielded 5.6–6.1% power conversion efficiencies, which were largely superior to those provided by other organic dyes previously proposed for the same application.