Targeted Passivation of Perovskite Defects Using Multifunctional 2D Composite Nanostructures to Reduce Recombination Losses in Photovoltaic Cells

Defect‐induced recombination dynamics remain an essential factor hindering the efficiency and stability of perovskite solar cells (PSCs). Herein, an upgraded solvent posttreatment strategy is proposed to simultaneously improve the quality and related electronic properties of absorbers by introducing the black phosphorus–graphene oxide (BP–GO) composites with a unique microscopic heterojunction stacking structure, high charge mobility, tunable bandgap, and excellent surface chemical properties into the grain boundaries and surface of the perovskite. The BP–GO composites block the layer‐to‐layer diffusion of active ions while directionally passivating uncoordinated defects in the perovskite, thereby accelerating the carrier extraction/transfer at the perovskite interface, ultimately significantly reducing the nonradiative recombination and interfacial charge recombination losses of the devices. The BP–GO composites improve Oswald ripening, guaranteeing the formation of high‐crystallinity and large‐grain perovskites, thereby significantly enhancing the lattice stability, interface quality, and light‐harvesting capacity of the absorbers. Benefiting from the synergistic action of the unique lattice structure of BP–GO, excellent passivation/isolation effect, and enhanced charge dynamics, the photovoltaic output performance of the BP–GO‐modified PSCs is significantly higher than that of conventional n– i –p planar PSCs, and the corresponding unencapsulated device exhibits good stability. This work provides theoretical and technical guarantees for achieving more efficient and stable planar PSCs.