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. Their successful use in nature during photosynthesis must be the inspiration for new artificial antenna systems. 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. 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. 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. 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 β-positions. Also, the influence of the anchoring groups in the cell performance is discussed. Studies containing chromophores other than porphyrin derivatives are not included in this work.

We report the fabrication and characterization of photovoltaic devices using a bulk heterojunction (BHJ) photoactive layer consisting of a small molecule (T), which contains a central p-phenylenevinylene unit, intermediate thiophene moieties, and terminal cyano-vinylene 4-nitrophenyls as the donor and a perylene–pyrene bisimide (PPI) as the acceptor. The difference in the LUMO levels (0.5 eV) of these materials is sufficient for the photoinduced charge transfer in the bulk heterojunction active layer. The optimum blend ratio (by weight) between T and PPI is 1 : 3.5 with a power conversion efficiency (PCE) of about 1.87%, beyond that the PCE starts to decrease. The incorporation of a thin ZnO layer between the organic BHJ layer and the top Al electrode increases the PCE to 2.46%, which is attributed to the enhanced light absorption due to the optical interference between incident light and reflected light from the Al electrode. It is also attributed to the improved electron transport in the device, since the conduction band of ZnO closely matches the work function of the Al electrode. The PCE is further increased to 3.17% when the device with the ZnO layer is annealed at a temperature of 100 °C for 5 min. This PCE is among the highest values reported to date for solar cells using solution processable small molecules.