In-Situ Crosslinked Fluorene Polymer for Efficient Perovskite Photovoltaics with Mitigated Lead Leakage

Abstract

Perovskite solar cells (PSCs) face challenges of interfacial defects, mechanical instability, and lead leakage. Here, we introduce a fluorene-based bisacrylate monomer (BPEFDA) that forms a crosslinked multifunctional polymer interlayer (P-BPEFDA) on the perovskite surface via in situ radical polymerization. This interlayer enhances interfacial adhesion and shear strength, while its carbonyl/ether groups and conjugated backbone passivate surface defects through Lewis acid–base and metal–π interactions. Additionally, P-BPEFDA optimizes energy-level alignment, boosts hole extraction, and suppresses ion migration. As a result, n i p PSCs and modules achieve efficiencies of 26.19% (0.09 cm2) and 22.24% (20.5 cm2), respectively, with excellent stability under various aging tests and a lead leakage suppression rate of ~97%. This work offers a versatile interfacial strategy for high efficiency, durable, and environmentally friendly perovskite photovoltaics.