Effects of Zn²⁺ ion doping on hybrid perovskite crystallization and photovoltaic performance of solar cells

To achieve a reproducible perovskite film with full surface coverage, Zn²⁺ ions are introduced to partially replace Pb²⁺ ions in this work. Results indicate that the crystallization and formation of CH₃NH₃Pb_1−xZn_xI₃ film with micrometer grain size could be changed by the micro-strain for lattice shrink. The bandgap and optical properties of perovskite films are improved due to trace amounts of Zn²⁺ ion dopant. More importantly, the solar cell device based on the Zn-doped perovskite film shows an increment in photocurrent of 21.13 mA cm⁻² and power conversion efficiency (PCE) of 16.6%. Electrochemical impedance spectroscopy (EIS) measurements reflect that the charge recombination resistance and charge accumulation capacitance of devices based on MAPb_0.98Zn_0.02I₃ film are lower than that of the control device. However, present results also implied that MAPb_1−xZn_xI₃ films are still necessary to be extensively developed and optimized for further enhancing the device photovoltaic performance.