Porphyrins in bio-inspired transformations: Light-harvesting to solar cell

Almost two decades after the outstanding X-ray crystallographic studies of light-harvesting antenna complex LH2 of the photosynthetic bacterium Rhodopseudomonas acidophila. a plethora of artificial mimics have been developed. It is well known that, in green plants, sophisticated self-assembled polypyrrolic architectures of photosynthetic units lead to efficient photo-induced electron transfer and by subsequent processes solar energy is stored in terms of chemical fuel in a very efficient way. The beauty and accuracy of light harvesting as well as the electron transfer process in natural photosynthesis are sources of inspiration for chemists, physicists and researchers of other disciplines to design artificial systems in order to convert solar energy into electricity or other forms of energy. More importantly, the understanding of the fundamentals of these processes is necessary in order to improve the design and the efficiency of artificial photoconversion systems, especially for photovoltaic applications. Porphyrins being ubiquitous in most of the natural pigments are an important building block for developing artificial molecular assemblies for solar photoconversion. The simplest mimicking unit of the natural photosynthetic center could be a porphyrin-derivative where an electron donor and an electron acceptor moiety are covalently linked or self-assembled via weak interactions. Intrinsic light-harvesting properties of porphyrins made them the best choice as sensitizers for organic photovoltaics, especially in photo-electrochemical dye-sensitized solar cells (DSSCs) or in hybrid solar cells. It is worth mentioning that, twenty years after the discovery of DSSC by Gratzel, a porphyrin based sensitizer has exhibited one of the highest efficiency (11.9%) reported so far. In this review, our aim is to highlight mostly the recent studies on porphyrin based bio-inspired materials for solar energy utilization. (C) 2012 Elsevier B.V. All rights reserved.