Simultaneous Charge Extraction Enhancement and Defect Passivation Via a Planar Conjugated Molecular Interface Enable...

Rational molecular design at the perovskite/hole transport layer (HTL) interface presents a viable strategy to suppress nonradiative recombination in CsPbI_3-xBr_x-based perovskite solar cells (PSCs). However, simultaneously achieving efficient defect passivation and rapid charge extraction with a single molecular modifier remains challenging. Herein, we employ a planar conjugated molecule, 1,8-naphthyridin-2-amine (2-NA), as a multifunctional interfacial modifier that concurrently enhances charge extraction and suppresses interfacial recombination in CsPbI_3-xBr_x PSCs. Combined density functional theory (DFT) calculations and experimental analyses reveal that 2-NA forms a dense protective layer via noncovalent interactions (e.g., π-π stacking and hydrogen bonding), effectively passivating undercoordinated Pb²⁺ while inhibiting ion migration. Remarkably, 2-NA incorporation facilitates hot-carrier extraction, reducing the carrier cooling time from 515 to 240 fs and quadrupling the carrier diffusion length, thereby improving charge transport. As a result, the optimized device achieves a power conversion efficiency (PCE) of 22.49%, the highest reported value for this class of PSCs to date. Furthermore, the device retains 93.6% of its initial PCE after 1008 h under ambient conditions, demonstrating exceptional stability. This work offers a promising molecular engineering approach for enhancing the performance and durability of inorganic PSCs through interfacial modification.