Dye-Sensitized Solar Cells

Although photovoltaic devices have been evolving for several decades but early 1990s witnessed an interesting development that of dye-sensitized solar cells (DSSCs). DSSCs significantly impacted further course of development of newer solar cell technologies. These photovoltaic devices (DSSCs) were radically different from all those that had been existing before. Though efforts had been made to use dye-sensitized photoelectrochemical cells to convert light into electricity in the past, it was with the work of O’Regan and Gratzel (Nature 353:737–740, 1991) that showed the feasibility of achieving significant photovoltaic conversion efficiency with use of dye-sensitized cells. There is an apparent similarity between the phenomenon of photosynthesis and working of dye-sensitized solar cells in which light harvested by dyes is converted into chemical and electrical energy, respectively. DSSCs are comprised of a dye-sensitized electrode which absorbs the light and generates the charge carriers, an electrolyte that serves as a hole transporter and establishes electrical continuity between electrodes, a counter-electrode at which the electron from the external circuit is transferred to the redox species in the electrolyte. The redox species helps in regeneration of the oxidized dye such that the photovoltaic cycle continues. In the past three decades extensive work has been carried out in understanding and improving the working of each component of the DSSCs yet owing to poor lifetime of the devices, limited conversion efficiency their commercialization has not taken place.