Lead fixation by spider web-like porphyrin polymer for stable and clean perovskite solar cells

Inhabiting the escape and migration of lead ions of perovskite films is crucial for the stable and clean perovskite solar cells (PSCs). The spider web is strong and sticky to catch the prey. Inspired by that, we employed an in-situ polymerized Zinc porphyrin (ZnP) with carbonyl group to fix lead into perovskite lattice to encapsulate the perovskite films. The carbonyl group can coordinate with lead ions in the modified perovskite films to inhibit the lead leakage when soaked into water, which could also reduce the trap density and suppressed non-radiative recombination within the modified film demonstrated by the space-charge-limited current, photoluminescence intensity and the electronic impedance spectroscopy measurements. Thus, the stabilities of the treated PSCs against heating and lighting improved obviously, and the optimal Power conversion efficiency (PCE) of PSCs also increased to 20.53% with the passivation of ZnP. This finding has provided an effective method to fix lead ions in the perovskite lattice.