Optically and Mechanically Engineered Anti‐Reflective Film for Highly Efficient Rigid and Flexible Perovskite Solar Cells

Abstract Sticker‐type anti‐reflective (AR) film is a powerful route to achieve the highest efficiency and commercialization of perovskite solar cells (PSCs) by improving the light transition efficiency (LTE). However, conventionally used AR film has high flexural rigidity owing to its limitation of material and thickness, thereby hindering its application to high‐efficiency flexible devices. This paper proposes a sticker‐type ultra‐thin perfluoropolyether (PFPE) AR film (SUPA) made of PFPE ( n = 1.34) that is fabricated through a well‐designed two‐step peeling propagation method. The proposed SUPA demonstrates superior properties in terms of LTE (≈98.3%) and film thickness (≈20 µm), exhibiting the best performance among the existing AR films for PSCs. The SUPA‐assisted rigid and flexible PSC guarantees high short‐circuit current density (rigid ≈26.63 mA cm −2 , flexible ≈23.05 mA cm −2 ) and power conversion efficiency (rigid ≈24.31%, flexible ≈20.05%). The SUPA sustains over 97.5% of its initial transmittance under exposure to the light (168 h) and damp heat condition (1000 h), and devices with SUPA show remarkable flexibility maintaining their initial efficiency after 10 000 cycles of a bending test (2 mm radius).