Copper Indium di-Selenium, CuInSe2 (CISe) is the most promising absorber material for thin-film solar cells. CISe based solar cells have shown long-term stability and the highest conversion efficiencies of all thin-film solar cells, above 19%. Moreover, CISe based solar cells are very stable and thus their operational lifetimes are long. The deposition method generally has a large impact on the resulting film properties as well as on the production costs. CISe can be prepared by a variety of methods like physical and chemical methods. The present review discusses first the liquid phase synthesis method like chemical bath deposition (CBD), electro-deposition (ED), spray pyrolysis (SP), and successive ionic layer adsorption and reaction method (SILAR), etc. Next, the structural, optical, electrical, and photo-electrochemical properties of CISe, as well as features of solar cells made thereof are reviewed. The last part of the text deals with the application of CISe thin-film absorbers in solar cells. The photo-response properties of the CISe are discussed how they can improve the efficiency and reduce the cost in potential applications.