Alternative sources of natural pigments for dye-sensitized solar cells: Algae, cyanobacteria, bacteria, archaea and fungi.

• Pigments from algae, cyanobacteria, bacteria, archaea and fungi can be used in DSSC. • Proteins, photosystems and reaction centers from organisms also act as sensitizers. • Biotechnological methods to obtain pigments are an ecofriendly alternative for DSSC. • Production, harvesting and scalability of these sensitizers can be controlled. • The range of photoconversion efficiency reached in DSSC vary between 0.001 and 4.6 %. Dye-sensitized solar cells have been of great interest in photovoltaic technology due to their capacity to convert energy at a low cost. The use of natural pigments means replacing expensive chemical synthesis processes by easily extractable pigments that are non-toxic and environmentally friendly. Although most of the pigments used for this purpose are obtained from higher plants, there are potential alternative sources that have been underexploited and have shown encouraging results, since pigments can also be obtained from organisms like bacteria, cyanobacteria, microalgae, yeast, and molds, which have the potential of being cultivated in bioreactors or optimized by biotechnological processes. The aforementioned organisms are sources of diverse sensitizers like photosynthetic pigments, accessory pigments, and secondary metabolites such as chlorophylls, bacteriochlorophylls, carotenoids, and phycobiliproteins. Moreover, retinal proteins, photosystems, and reaction centers from these organisms can also act as sensitizers. In this review, the use of natural sensitizers extracted from algae, cyanobacteria, bacteria, archaea, and fungi is assessed. The reported photoconversion efficiencies vary from 0.001 % to 4.6 % for sensitizers extracted from algae and microalgae, 0.004 to 1.67 % for bacterial sensitizers, 0.07−0.23 % for cyanobacteria, 0.09 to 0.049 % for archaea and 0.26–2.3 % for pigments from fungi. [ABSTRACT FROM AUTHOR]