Currently, energy and greenhouse gas emissions are the biggest problems. As a result of overpopulation and high energy consumption, non-renewable energy sources are continuously depleting. Greenhouse gases are also being emitted at a very high rate. The modern world must use renewable energy sources, among which solar energy is safe and available everywhere. Solar energy is efficiently transformed into electrical energy by photovoltaics (solar cells). During the past decades, DSSC the type of thin-film photovoltaics, gained importance due to cost-effectiveness, durability, ease fabrication, and low toxicity. These cells convert sunlight into electricity with power conversion efficiency approximately 20%. Glass substrate, photo-anode, sensitizer, electrolyte and counter electrode are the key components of DSSCs. Among these, sensitizers are the most important part of these cells that absorb photons, generate electrons, create electron-hole-pair and produce electricity. In the beginning, only ruthenium metal complexes were used as dyes, but now a large number of organic, inorganic and natural compounds are widely used to enhance the overall performance of these cells. This is in-depth review on solar cells but mainly focus on construction, operating principle, and performance of DSSCs. In this review, we not only presented a library of sensitizers used in DSSCs but also give a brief comparison between these sensitizers to help future research.