Photothermal-Stable Flexible Perovskite Solar Cells Enabled by PbI2 Suppression with Amino-Functionalized Graphene Quantum Dots

Abstract

The upper interface of inverted flexible perovskite solar cells (FPSCs) is prone to degradation under photothermal stress, leading to the formation of lead iodide (PbI2) that severely compromises both device efficiency and operational stability. Herein, we propose amino-functionalized graphene quantum dots (A-GQDs) as a versatile upper interface modifier to address this critical challenge. The abundant Lewis base groups on A-GQDs establish strong coordinated bonding with uncoordinated Pb2+ and form synergistic hydrogen bonding networks with iodide ions and organic cations, enabling effective defect passivation, favorable energy level alignment, and substantial residual stress release. Remarkably, the A-GQDs layer consistently inhibits photothermal-induced PbI2 generation and effectively blocks ionic migration during device operation. Benefiting from this multifunctional interface engineering, the optimized flexible devices achieve a champion power conversion efficiency (PCE) of 23.11%, along with exceptional stability under continuous photothermal aging, mechanical bending, and damp heat exposure. This work presents a new interfacial engineering paradigm that synergistically integrates defect passivation, stress relief, and Synergistic stabilization for high-performance flexible photovoltaics.