High-performance perovskite solar cells by incorporating a ZnGa₂O₄:Eu³⁺ nanophosphor in the mesoporous TiO₂ layer

ZnGa₂O₄:Eu³⁺ nanophosphor was synthesized through a hydrothermal method and used as an effective light down-shifting/converting material in mesoporous TiO₂ layer of perovskite solar cells (PSCs). The nanophosphor can convert the high energy incident photon into the photon(s) with lower energy, which can excite CH₃NH₃PbI₃ to generate more photo generated electron-hole pairs, and thus promote the incident light use ratio and increase the power conversion efficiency (PCE) of PSCs. After the incorporation of suitable amount of ZnGa₂O₄:Eu³⁺ into PSCs, the cell PCE is increased to 13.80% with a photocurrent density of 23.68 mA cm^-2 and a highest PCE of 14.34% with a photocurrent density of 25.02 mA cm^-2 is achieved, much higher than those of the cell without ZnGa₂O₄:Eu³⁺ (PCE of 10.67% and photocurrent density of 20.2 mA cm^-2). The enhanced photovoltaic performance by incorporating the nanophosphor into PSCs should be ascribed to the increased incident light use ratio and improved exciton generation rate.