Toward Scalable Light Management in Fragile Thin Film Energy Materials via Self-Organized Photonic Interfaces

Light management is critical for thin-film energy devices, where interfacial optical losses can exceed 10-20% of incident photons. Despite well-established photonic concepts, implementation remains limited by the incompatibility of conventional nanopatterning with fragile energy materials, restricting the scalable performance gains. In this perspective, we argue that effective light management requires decoupling optical functionality from material constraints. We highlight laser-induced periodic surface structures generated by femtosecond-laser processing as a scalable, maskless approach to create photonic interfaces while preserving optoelectronic quality. Using CsPbI₃ thin films as a model system, we demonstrate direct formation of surface gratings leading to reduced reflectivity and enhanced absorption (∼10%) through diffraction-driven light coupling and optical path-length extension. Self-organized photonic interfaces thus provide a general strategy for scalable optical optimization across a broad range of thin-film energy technologies.