Microbial Screening for Solar Energy Suppliers Production via Fermentation Processes

Environmental sustainability and circular economy are gaining more and more attention by the scientific and industrial communities. This is leading to the implementation of new eco-friendly materials in several sectors. The development of new third-generation photovoltaic cells, named dye-sensitized solar cells (DSSCs), produced by using microbial dyes, is recently gaining more interest in meeting the demand of sustainable devices. The present research is aimed to the screening of different microbial strains, cultivated under controlled fermentation processes, for producing dyes for DSSCs development. The microbial pigments obtained have been characterized by HPLC-DAD-ESI-MS analyses and evaluated for their suitability as photosensitizers. The absorbance intensity was measured by UV-vis, while the devices' photovoltaic parameters and impedance characteristics were obtained by applying Photoelectrochemical and Electrochemical Impedance Spectroscopy (EIS) analyses and IV measurements. Among the microbial pigments evaluated, the best results have been reached out both when the single carotenoidic extract enriched in astaxanthin, produced by Paracoccus carotinifaciens, and when the extracts from Talaromyces atroroseus GH2 and Paracoccus bogoriensis BOG6 have been applied in co-sensitization, obtaining the highest efficiencies values of 0.36% and 0.34% respectively. Even though the photovoltaic parameters of the implemented devices are low compared with those obtained by using synthetic dyes, the presented results denote an important achievement towards the development of greener solar cells using natural dyes obtained by microbial sources.