Hydrophobic surface release and energy-level alignment of PTAA enables stable flexible perovskite solar modules

The fabrication of efficient and stable flexible perovskite solar modules (F-PSMs) using poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) remains a significant challenge due to its hydrophobic properties and the mismatch in interface energy-level alignment. Here, we introduced [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) to modify the PTAA layer, which effectively suppressed surface potential fluctuations and aligned energy levels at the interface of PTAA/perovskite. Additionally, MeO-2PACz enhanced the hydrophilicity of PTAA, facilitating the fabrication of dense, uniform, and pinhole-free perovskite films on large-area flexible substrates. As a result, we achieved an F-PSM with a power conversion efficiency (PCE) of 16.6% and an aperture area of 64 cm², which is the highest reported value among F-PSMs with an active area exceeding 35 cm² based on PTAA. Moreover, the encapsulated module demonstrated outstanding long-term operational stability, retaining 90.2% of its initial efficiency after 1000 bending cycles (5 mm radius), 87.2% after 1000 h of continuous illumination, and 80.3% under combined thermal and humid conditions (85 °C and 85% relative humidity), representing one of the most stable F-PSMs reported to date.