Dyed sensitized solar cells: A technically and economically alternative concept to p-n junction photovoltaic devices

Nanocrystalline dyed sensitized solar cells (DSSC) are photo-electrochemical cells based on principles similar to the processes in natural photosynthesis. They are based on photo sensitization of nanocrystalline semiconductor electrodes by absorbed dyes. The DSSC provides a technically and economically credible alternative concept to present day p–n junction photovoltaic devices. The DSSC work on a different principle, whereby the processes of light absorption and charge separation are differentiated. This is in contrast to the conventional systems where the semiconductor assumes both the task of light absorption and charge carrier transport. In the DSSC, the bulk of the semiconductor is used solely for charge transport; the photoelectrons are provided from a separatephotosensitive dye. Charge separation occurs at the surfaces between the dye, semiconductor and electrolyte. This paper introduces the structure and operating principles of dye sensitized solar cells (DSSC). The key components including the semiconductor oxides, conducting substrates, the dye sensitizers, the electrolytes and the counter electrodes used in dye sensitized solar cell was reviewed in details. The result of various researches done especially to improve the performance and the conversion efficiency of the dye cell was presented. Hence this paper reviews the progress which has been made and the mechanism involved in the operation of dye sensitized solar cell.   Key words: Dye sensitized solar cell, nanocrystalline oxide semiconductor, counter electrodes, electrolytes, dyes.