“…To solve problems found in both metal-based complex and metal-free organic dyes, researchers have focused on natural plant pigment-based photosensitizer [71]. As a result, metal-free dyes, such as natural dyes (natural pigments) from different plant sources such as fruits, roots, flowers, leaves, wood, algae, and bacterial pigments [72,73], coupled with their organic derivatives, have attracted considerable research interest, owing to their low-cost, simple synthesis procedure, abundance in nature, nontoxicity, and high molar absorption coefficient [35,74] It is important to note that the stable natural plant pigments extracted by effective solvents can absorb a broad range of visible light [79,80], because the two most significant drawbacks of DSSCs are their narrow spectral response and short-term stability. Therefore, in this review work, different natural plant pigments are extracted from different plant parts such as leaves, roots, steam, parks, peel waste, flowers, various spices, and a mixture of them with various solvents, and their stability and various experimental factors are effectively discussed.…”