Efficient inverted FA–Cs perovskite solar modules fabricated by blade-coating on PET foils with robust encapsulation

Abstract

The commercial deployment of perovskite photovoltaics (PV) hinges on bridging the gap between high-efficiency lab-scale devices and scalable, reliable modules. While flexible polymeric substrates offer a pathway to high-throughput roll-to-roll (R2R) manufacturing, achieving long-term operational stability on these platforms remains a critical challenge. Here, we report a robust strategy for the scalable manufacturing of efficient inverted formamidinium-cesium (FA-Cs) flexible perovskite solar modules (FPSMs), complemented by an industrially compatible encapsulation sequence. By employing a modified gas-assisted blade-coating process, combined with a gradual annealing protocol utilizing the thermal mass of a PDMS-covered copper plate (≤100°C), we demonstrate a unified processing framework applicable to FA–Cs perovskite compositions of different bandgaps. In the device architecture, we employed a synergistic interface engineering approach utilizing the self-assembling molecule 4-((5H-diindolo[3,2-a:3',2'-c]carbazole-5,10,15-triyl)tris(butane-4,1-diyl))tris(phosphonic acid) (TRIPOD-C4) as an effective hole-transporting layer, combined with propane-1,3-diammonium iodide (PDAI2) for perovskite surface passivation. As a result, blade-coated FA–Cs PSCs with bandgaps of 1.61 eV and 1.76 eV achieved power conversion efficiencies (PCEs) of 20.4% and 17.4%, respectively. When scaled to modules, we recorded champion efficiencies of 17.0% and 15.1% for the medium- and wide-bandgap absorbers, respectively. Furthermore, we demonstrate a production-compatible vacuum lamination protocol utilizing ultra-high barrier foils. The encapsulated FPSMs exhibit promising durability, retaining 80% of their initial efficiency after 1026 hours of damp-heat aging (ISOS-D3, 85 °C/85% RH).