Hysteresis-less mesoscopic CH₃NH₃PbI₃ perovskite hybrid solar cells by introduction of Li-treated TiO₂ electrode

A great current density-voltage (J-V) hysteresis with respect to the scan direction is important issue in perovskite hybrid solar cells because the power conversion efficiency is sometimes incorrect. Here, we demonstrated >17% mesoscopic CH₃NH₃PbI₃ (MAPbI₃) perovskite hybride solar cells without significant J-V hysteresis with respective to the scan direction and rated by using Li-treated mesoscopic TiO₂ electrode. The Li-treated mesoscopic TiO₂ electrode improved charge separation/injection from MAPbI₃ into mesoscopic TiO₂, charge transport in mesoscopic TiO₂, and surface traps because the conduction band edge of mesoscopic TiO₂ was lowered by ~0.1eV, the mobility of charge carriers was increased from ~1.1×10^-6cm²/Vs to ~2.5×10^-6cm²/Vs, the conductivity of mesoscopic TiO₂ was increased from ~5.6×10^-7S/cm to ~1.6×10^-6S/cm, and the trap density was reduced from ~1.2×10¹⁶cm^-3 to ~9.3×10¹⁵cm^-3 through Li-treatment. Therefore, the average power conversion efficiency was significantly enhanced from 14.84% to 17.26% at 1sun condition by the Li-treatment of mesoscopic TiO₂.