Polymerization Strategies to Construct a 3D Polymer Passivation Network toward High Performance Perovskite Solar Cells

The spontaneously formed uncoordinated Pb2+ defects usually make the perovskite films demonstrate strong n‐type with relatively lower carrier diffusion length and serious non‐radiative recombination energy loss. In this work, we adopt different polymerization strategies to construct three‐dimensional passivation frameworks in the perovskite layer. Thanks to the strong C≡N⋅⋅⋅Pb coordination bonding and the penetrating passivation structure, the defect state density is obviously reduced, accompanied by a significant increase in the carrier diffusion length. Additionally, the reduction of iodine vacancies also changed the Fermi level of the perovskite layer from strong n‐type to weak n‐type, which substantially promotes the energy level alignment and carrier injection efficiency. As a result, the optimized device achieved an efficiency exceeded 24 % (the certified efficiency is 24.16 %) with a high open‐circuit voltage of 1.194 V, and the corresponding module achieved an efficiency of 21.55 %. A three‐dimensional polymer passivation network was constructed by combining the bulk in situ polymerization and surface pre‐polymerization/secondary polymerization strategies. The all‐rounded passivation structure increased carrier diffusion length, promoted energy level alignment and carrier injection. Corresponding devices achieve a high open‐circuit voltage of 1.194 V with an efficiency over 24 %, and module also achieves an efficiency of 21.55 %.