Emerging DSSC designs: Comparative insights into purified and crude natural dyes as sensitisers

Dye-sensitised solar cells (DSSCs) sensitised with natural dyes are among the emerging solar cell technologies that have attracted significant interest among researchers due to their abundance, ease of preparation, and biodegradability. This review highlights emerging DSSC technologies, with emphasis on the use of purified and crude natural dyes as sensitisers. Few available literature reviews surveyed on purified versus crude dyes as sensitisers indicate that crude dyes outperform purified dyes in DSSC applications. Since most crude dyes contain pigments that support both the absorption spectrum and the adsorption of the dye onto semiconductor oxides. Moreover, research findings on limitations and future prospects of using purified or crude natural dyes as sensitisers in DSSCs are uncertain. This shows that the more efforts that are being explored require further future work to improve the performance of both crude and/or purified natural DSSC devices. To boost the efficiency of natural dyes, some strategies, such as co-sensitisation, co-adsorbents, and cocktail dye techniques, have been suggested and used in the literature and are surveyed and discussed in this paper. Furthermore, cocktail dyes comprising natural and synthetic organic dyes can be superior, as many synthetic dyes have high molar extinction coefficients, and their flexible modifications can enable probing some DSSC issues, such as bonding to semiconductor oxides and dye aggregation.