Dye sensitized solar cells go beyond using perovskite and spinel inorganic materials: A review

The inorganic perovskite and spinel materials have exhibited lots of desirable characteristics which make them promising materials for usage in dye sensitized solar cells (DSSCs). Photoanode in DSSCs is made up of a metal oxide semiconductor (usually TiO2). To attain high power conversion efficiency (PCE) for a DSSC, photoanode should reveal high amounts of dye adsorption, light scattering and photoelectron injection. The TiO2 photoanode displays several drawbacks such as long dye absorption time, low electron mobility, formation of complex with the dye molecules, and relatively high recombination of charges at its interface with the electrolyte. Accordingly, other metal oxides such as spinel and inorganic perovskite compounds could be utilized to replace and/or modify the TiO2 photoanode of DSSCs. The mineral spinel is zinc aluminate (ZnAl2O4) and the spinel materials have the general AB(2)X(4) formula, where A, B show metal cations while X represents anions such as O(2-)and halide (F-, Cl-, Br-, I-) anions. The mineral perovskite is calcium titanate (CaTiO3) and the formula of the perovskite materials is commonly illustrated as the ABX(3), where X represents the anions and A, B display metal cations. Herein, a comprehensive review was accomplished on using the perovskite and spinel materials in photoanodes of DSSCs. The studied inorganic perovskite materials were BaSnO3, BaTiO3, SrTiO3, CdSnO3, CoTiO3, Ba3Ti4Nb4O21 and A(2)LuTaO(6) (A = Ba, Sr, Ca) and the spinel materials included Zn2SnO4, CuBi2O4, NiCr2O4, SrAl2O4 and ZnFe2O4 structures. It was displayed that the PCEs of the fabricated DSSCs were enhanced upon employing certain amounts of the perovskite or spinel materials.