Synergistic Buried-Interface Dipole Modulation and Conductive Nanofiber Engineering for High-Performance Flexible Perovskite Solar Cells

Flexible perovskite solar cells (f-PSCs) suffer from buried-interface energy-level mismatch, severe interfacial recombination, and inefficient charge transport, which limit both device efficiency and stability. Herein, we develop a synergistic strategy by integrating a trimethoxy[3-(phenylamino)propyl] silane (TEPAPS) dipole interlayer with conductive SnOx/C nanofibers (NFs) to simultaneously regulate the buried interface and perovskite bulk. The TEPAPS interlayer reduces the work function, improves energy-level alignment, and passivates interfacial Pb2+ defects. Meanwhile, TEPAPS-modified SnOx/C NFs act as conductive one-dimensional frameworks and crystallization templates, promoting grain growth, reducing defect density, and establishing efficient charge-transport pathways throughout the perovskite layer. As a result, nonradiative recombination is effectively suppressed and carrier extraction is accelerated. Owing to the synergistic effects of interfacial dipole modulation and conductive nanofiber engineering, the optimized rigid device and flexible devices achieve power conversion efficiencies (PCEs) of 24.11% and 21.63%, respectively. Moreover, the flexible device retains 88.2% of its initial efficiency after 600 bending cycles. This work provides an effective approach for simultaneously engineering buried-interface energetics and bulk charge transport for high-performance flexible perovskite photovoltaics.