Keratin‐Based Skin‐Tone Camouflage Coating for Aesthetic Integration of Perovskite Solar Cells

Abstract Perovskite solar cells (PSCs) offer high power conversion efficiency and low‐cost fabrication, yet their use in wearable and consumer‐facing technologies is limited by aesthetic constraints. This study introduces keratin‐based coatings as skin‐tone camouflage layers that preserve photovoltaic performance. Inspired by the stratum corneum, three formulations are developed: pure keratin (KER), keratin–melanin (KML), and keratin–KerMel (KKM), the latter incorporating synthetic melanin‐mimetic particles. These coatings may serve as UV‐protective top layers for PSCs. Characterization revealed that KKM exhibited nanoscale uniformity and enhanced durability, contributing to superior light management. KML showed the strongest UV‐blocking capacity but reduced transparency, while KER offered high transparency with limited protection. Mechanical testing confirmed the robustness of all coatings, with tensile strengths of ≈3 MPa (KML), ≈2.5 MPa (KKM), and ≈1.7 MPa (KER). The KKM coating achieved a power conversion efficiency of ≈12%, compared to ≈15% in the uncoated reference, and outperformed both KER (≈10%) and KML (≈8%). Stability testing showed KKM retained ≈79% of its initial performance after 14 days, exceeding KER and KML, though slightly below the uncoated device. These results highlight keratin‐based coatings as viable materials for merging functionality and aesthetics in renewable energy and biomedical applications.