Despite the remarkable performance progress being made, environmental concerns remain for lead halide perovskite solar cells (PSCs) because of the possible water dissolution of lead ions (Pb2+) into the environment. Herein, we succeed in mitigating Pb leakage of PSCs, for the first time, via implanting in situ polymerized networks into perovskites. We strategically transform the dormant monomer additives into chelating polymer networks within perovskite layers, which not only passivate the defects of perovskite but also protect Pb2+ from water dissolution. The resultant perovskite–polymer hybrids have successfully enabled state-of-art power conversion efficiencies (PCEs) for inverted PSCs (PCE of 22.1%) and large-area modules (PCE of 15.7%). More importantly, up to 94% rejection rate of Pb2+ dissolution is achieved upon directly immersing the unencapsulated devices into water, which reasonably simulates the exposure of the broken and unprotected panels to torrential rain for 24 h.

Although the 2D spacer modification is widely studied in perovskite solar cells (PVSCs), the energy level alignment between the 2D/3D interfaces makes it unfavorable for top surface passivation in the inverted p-i-n device structure. To address this issue, the effect of bottom interface modification is studied with three representative 2D spacers, i.e., the Ruddlesden-Popper 2D spacer, Dion-Jacobson 2D spacer, and strong passivation 2D spacer, in inverted p-i-n PVSCs. After optimization, the PVSCs with these 2D spacer modifications universally exhibit the best efficiencies of ≈21.6%, which constitutes dramatic improvement compared to the control device (20.7%). By lifting off the perovskite layer, the optoelectronic properties of the bottom surface are studied, and the mechanism underlying the improved device performance is unveiled to be uniformly originated from the formation of 2D/3D heterojunction, where the cascade valence band facilitates the hole collection and electron back scattering field suppresses the charge recombination at the anode interface. Besides, the unencapsulated device retains 90% of initial efficiency after 30 days of storage in ambient air with a relative humidity of 30 ± 5%, indicating excellent stability against moisture and oxygen. This study provides insight into the bottom interface modification with diverse 2D spacers for high-performance p-i-n structured PVSC devices.