Dye-sensitised solar cells: Development, structure, operation principles, electron kinetics, characterisation, synthesis materials and natural photosensitisers

The energy economy is highly dependent on oil, coal and natural gas, which constitute 37%, 27% and 20% of energy usage, respectively. However, the reserves of fossil fuels (e.g., crude oil) are limited and could run out in approximately 40 years based on a daily consumption of 82.5 million barrels and the current reserves to production (R/P) ratio. Solar energy is the source of nearly all energy on Earth. Of all renewable power sources, solar energy is the most easily exploitable, inexhaustible, quiet, and adaptable to different applications. Photovoltaic cells (PVCs) are devices that directly convert sunlight into electricity without pollution, sound, or moving parts, which makes them long-lasting and dependable. PVCs use an elegant method to take advantage of sunlight. Solar cells offer one of the most promising and environmentally friendly methods for producing electricity. This paper reviews the emergence, principles, electron kinetics and components of PVCs with a focus on the molecular engineering of several metal complexes, organic dyes and natural dyes that are used as photosensitisers in dye-sensitised solar cells (DSSCs).