Perovskite solar cells (PSCs) have attained considerable attention owing to their high-power conversion efficiency (PCE) and low manufacturing costs. However, the inadequate stability and lead leakage issues of PSCs remain as critical challenges impeding their practical implementation. In this work, we adopt an in situ self-polymerization strategy, with three monomers (N-Methylol acrylamide (NMA), N-(2-Hydroxypropyl) methacrylamide (2-HPMA), and N-(4-Hydroxyphenyl) methacrylamide (4-HPhMA)) introduced into the perovskite film. NMA and 2-HPMA undergo self-polymerization during the thermal annealing of the perovskite films, forming internal encapsulation within the perovskite film. In addition, the hydrogen bonding and chelating interactions between the perovskite and the polymers effectively suppress the defect states and significantly enhance the quality of perovskite films. Thus, the efficiency of devices increases from 22.41% to 25.06% after 2-HPMA modification. Moreover, the internal encapsulation effect induced by 2-HPMA endows PSCs with better long-term stability and humidity resistance. The unencapsulated device can retain 88% of its original PCE after storage in ambient air for 1000 h, and 86% of its pristine PCE after aging for 100 h at 60%‒80% relative humidity (RH) conditions. Furthermore, the interaction between the polymers and lead can largely inhibit lead leakage from unencapsulated PSCs.

CsPbI₂Br perovskite solar cells have achieved rapid development owing to their exceptional optoelectronic properties and relatively outstanding stability. However, open-circuit voltage (V_oc) loss caused by band mismatch and charge recombination between perovskite and charge transporting layer is one of the crucial obstacles to further improve the device performance. Here, we proposed a bilayer electron transport layer ZnO(bottom)/SnO₂(top) to reduce the V_oc loss (E_loss) and promote device V_oc by ZnO insert layer thickness modulation, which could improve the efficiency of charge carrier extraction/transfer and suppress the charge carrier recombination. In addition, guanidinium iodide top surface treatment is used to further reduce the trap density, stabilize the perovskite film and align the energy levels, which promotes the fill factor, short-circuit current density (J_sc), and stability of the device. As a result, the champion cell of double-side optimized CsPbI₂Br perovskite solar cells exhibits an extraordinary efficiency of 16.25% with the best V_oc as high as 1.27 V and excellent thermal and storage stability.