High efficiencies have been achieved for TiO 2 -based devices sensitized, for example, with free-base and zinc porphyrin derivatives, presenting one or more carboxylic acid appends as anchoring groups, either in β or meso positions of the porphyrin central core, and also with multiple donor groups at the meso positions. After thorough investigations, there is a general agreement on the structural requirements of porphyrins to be used in DSSCs: 1) at least one anchoring group must be present for the covalent binding to the semiconductor surface, 2) metallic complexes (MP), especially the zinc ones, are preferred to free-base (H 2 P), because of their longer-lived singlet excited states and much lower oxidation potentials, and 3) bulky electron-donor meso-substituents favor electron injection in the semiconductor, as they originate an intrinsic dipole moment. Dye sensitized solar cells (DSSC) is one of these fields where porphyrin compounds have been widely employed, usually playing the role of sensitizing dyes. is critically analyzed which will be helpful to find a pathway in fine tuning the structure of the photosensitizer to meet the requirements of photovoltaic applications. Also, the progress in the structural modification of bio-inspired porphyrin based systems through introducing donor-acceptor moieties, metallation, nanoarchitecture designs, cosensitization strategies etc. This chapter discusses how the structural features of the porphyrin dyes are being exploited in various electron transfer processes of natural systems. From evaluation of these dyes, it is evident that 12 peripheral positions of the porphine core available for substitution makes it superior to other sensitizers. In this chapter the application of porphyrin based dyes for photovoltaics is highlighted. Light harvesting ability of these molecules finds applications in various fields such as dye sensitized solar cells, photodynamic therapy, bio-imaging and in therapeutics. Inspired from such systems, scientists have been keenly trying to mimic and elaborate it. Prior to the birth of DSSC itself, there existed porphyrins as light harvesting molecules in nature. In the era of dye sensitized solar cells (DSSC), maximum efficiency reaches up to 14.2%, achieved by using porphyrin based photosensitizers. Studies containing chromophores other than porphyrin derivatives are not included in this work. ![]() Also, the influence of the anchoring groups in the cell performance is discussed. For this reason we have attempted to describe the developments in the DSSCs of various porphyrin dyes with different anchoring groups linked through either meso or beta-positions. This review provides a summary of some of the most important developments and approaches that are used in order to improve the light collection efficiency of DSSCs based on porphyrin hybrid derivatives. ![]() Specifically, their high absorption ability in the visible region can be extended, and electron donor and anchoring groups with high chemical affinity to the cell should be part of the new design. ![]() Porphyrins offer an excellent platform for building such multi-chromophoric systems to self-assemble because of the availability of several substituent sites and their intrinsic spectroscopic properties. Their successful use in nature during photosynthesis must be the inspiration for new artificial antenna systems. In the design of new chromophores, with high efficiency, chemical stability and low cost materials for dye sensitized solar cells, porphyrin macrocycles could play a very important role.
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