Review on natural dye sensitized solar cells: Operation, materials and methods

Dye sensitized solar cells (DSSC) have become a topic of significant research in the last two decades because of their fundamental and scientific importance in the area of energy conversion. Ease of fabrication with widely available materials coupled with reasonable efficiency has made DSSC a promising candidate in low cost solar cells and its research. The use of synthetic dyes as sensitizer in DSSC provide better efficiency and high durability, but they suffer from several limitations such as higher cost, tendency to undergo degradation, and usage of toxic materials. These limitations have opened up for alternate sensitizers that are bio compatible natural sensitizers. Natural sensitizers contain plant pigments such as anthocyanin, carotenoid, flavonoid, and chlorophyll that are responsible for chemical reactions such as absorption of light as well as injection of charges to the conduction band of TiO2 by the sensitizer. Therefore, dyes containing these pigments can easily be extracted from natural products like fruits, flowers, leaves, seeds, barks etc and can be employed as sensitizer for DSSC.

The main objective of this review is to discuss the operation of natural dye based DSSC along with the various components that are present in it. It also details and tabulates the various plant pigments present in the natural products which are employed as sensitizer in DSSC. Furthermore, a detailed summary of the work carried out by different research groups on natural dye based DSSC is also reviewed. Issues on stability and future development of natural dye based DSSCs have been addressed.