Enhanced short-circuit current density of perovskite solar cells using Zn-doped TiO₂ as electron transport layer

In present work, we focused on the improvement of short-circuit current density (J_sc) by using zinc-doped TiO₂ (Zn-doped TiO₂) as electron transport layer. Various Zn-doped TiO₂ compact layers with different doping concentrations are prepared by sol-gel method followed thermal treatment, and they were then used to fabricate perovskite solar cell. Effects of zinc (Zn) on the power conversion efficiency (PCE), absorption behavior, crystal structure, electrical conductivity, and surface morphology are systemically elucidated. Charge carrier dynamics between perovskite active layer and titanium dioxide (TiO₂) compact layer is discussed too. When the dopant concentration is less than 5.0 mol%, the absorption behavior, electrical conductivity and charge separation efficiency increase with Zn doping concentration. In contrast, when the Zn dopant is 7.0 mol%, it results in the decay of these properties mentioned. According to the optimized processing of perovskite solar cells, the J_sc is increased from 18.5 to 22.3 mA/cm² so as to the PCE is significantly improved from 11.3% to 14.0%.