Organometal perovskite light absorbers toward a 20% efficiency low-cost solid-state mesoscopic solar cell

Recently, perovskite CH₃NH₃PbI₃ sensitizer has attracted great attention due to its superb light-harvesting characteristics. Organometallic or organic materials were mostly used as sensitizers for solid-state dye-sensitized solar cells at early stages. Inorganic nanocrystals have lately received attention as light harvesters due to their high light-absorbing properties. Metal chalcogenides have been investigated with solid-state dye-sensitized solar cells; however, the best power conversion efficiency was reported to be around 6%. CH₃NH ₃PbX₃ (X = Cl, Br, or I) perovskite sensitizer made a breakthrough in solid-state mescoscopic solar cells, where the first record efficiency of around 10% was reported in 2012 using submicrometer-thick TiO ₂ film sensitized with CH₃NH₃PbI₃. A rapid increase in efficiency approaching 14% followed shortly. In this Perspective, recent progress in perovskite-sensitized solid-state mesoscopic solar cells is reviewed. On the basis of the recent achievements, a power conversion efficiency as high as 20% is expected based on optimized perovskite-based solid-state solar cells.