Ruthenium doped mesoporous titanium dioxide for highly efficient, hysteresis-free and stable perovskite solar cells

The electron transporting layer (ETL) plays a vital role in the power conversion efficiency (PCE) of perovskite solar cells (PSCs). We have demonstrated the synthesis of ruthenium doped mesoporous TiO₂ (Ru-TiO₂) and their utility as ETLs for PSCs. The doping effects of Ru⁴⁺ on the electronic and photovoltaic properties of mesoporous TiO₂ (mp-TiO₂) have been investigated as well. The highest PCE of 18.94% was obtained with 0.1 M Ru-TiO₂ PSCs exhibiting an open circuit voltage (V_OC) of 1.128 V, current density (J_SC) of 22.55 mA cm⁻², and fill factor (FF) of 76.55%, whereas the conventional mesoporous PSCs showed PCE = 16.80%, V_OC = 1.095 V, J_SC = 21.50 mA cm⁻², and FF = 70.01%. Note that the 0.1 M Ru-TiO₂ device shows high PCE with negligible hysteresis index, high reproducibility and more stability as compared to conventional mesoporous PSCs.