Light-converting polymer coatings and films are emerging passive photonic materials for spectral engineering in sustainable and protected agriculture. By absorbing ultraviolet or weakly used spectral components and re-emitting in visible bands that overlap with photosynthetic pigments and plant photoreceptor action regions, these materials can modify the radiation environment without additional electrical energy input. This critical review analyses light-converting polymer films and coatings from a materials and coatings perspective, with emphasis on photophysical mechanisms, polymer matrices, luminophore families, coating fabrication routes, optical transparency, photoluminescence, aggregation phenomena, photostability and scalability. The photobiological background is included as a concise framework that justifies the spectral targets of the conversion process. Rare-earth complexes, inorganic phosphors, quantum dots, aggregation-induced-emission systems and organic dyes are compared as candidate luminophores. Particular attention is paid to an author-developed perylene diimide (PDI)-modified poly(methyl methacrylate) (PMMA) solution-cast coating system, used here as a representative case study to discuss dispersion, optical homogeneity and aggregation-related losses. Extrusion, solution casting, spin-coating, dip-coating and sol–gel processing are evaluated as fabrication strategies for laboratory and large-area greenhouse applications. The work concludes by identifying the main gaps that must be addressed before practical deployment: quantitative UV–Vis and photoluminescence characterization, absolute quantum yield, haze and scattering, thickness and morphology mapping, accelerated UV ageing, weathering resistance, toxicity assessment and crop-specific validation.

Air purification is a key process aimed at removing harmful impurities and providing a safe and comfortable environment for human life and work. This study presents the results of an investigation into the composition, textural, and sorption properties of a multichannel carbon filtering material developed for air purification from biological (infectious) contaminants. The filtering block has a cylindrical shape and is manufactured by extrusion of a plastic composition based on carbonized rice husk with the addition of binding agents, followed by staged thermal treatment (calcination, activation, and demineralization). The filter’s effectiveness is based on the inactivation of pathogenic microorganisms as the air passes through the porous surface of the sorbent, which is modified with broad-spectrum antiseptic agents (active against bacteria, bacilli, fungi, and protozoa). X-ray diffraction analysis revealed the presence of amorphous carbon in a tubostratic structure, with a predominance of sp- and sp²-hybridized carbon atoms not incorporated into regular graphene lattices. IR spectroscopy demonstrated the presence of reactive functional groups characteristic of the developed porous structure of the material, which is capable of selective sorption of antiseptic molecules. SEM surface analysis revealed an amorphous texture with a loose structure and elements in the form of spherical semi-ring formations formed by overlapping carbon plates. An experimental setup was also developed using cylindrical multichannel carbon blocks with a diameter of 48 mm, a length of 120 mm, and 100–120 longitudinal channels with a cross-section of 1 mm². The obtained results confirm the potential of the proposed material for use in air purification and disinfection systems under conditions of elevated biological risk.

Light-converting polymer coatings and films are emerging passive photonic materials for spectral engineering in sustainable and protected agriculture. By absorbing ultraviolet or weakly used spectral components and re-emitting in visible bands that overlap with photosynthetic pigments and plant photoreceptor action regions, these materials can modify the radiation environment without additional electrical energy input. This critical narrative review analyses light-converting polymer films and coatings from a materials and coatings perspective, with emphasis on photophysical mechanisms, polymer matrices, luminophore families, coating fabrication routes, optical transparency, photoluminescence, aggregation phenomena, photostability and scalability. The photobiological background is included as a concise framework that justifies the spectral targets of the conversion process. Rare-earth complexes, inorganic phosphors, quantum dots, aggregation-induced-emission systems and organic dyes are compared as candidate luminophores. Particular attention is devoted to the general challenges associated with organic luminescent coatings, including dispersion, aggregation, optical transparency, photostability, and scalability. A PMMA/PDI coating system is discussed only as an illustrative case study demonstrating these broader materials-design considerations. Extrusion, solution casting, spin-coating, dip-coating and sol–gel processing are evaluated as fabrication strategies for laboratory and large-area greenhouse applications. The work concludes by identifying the main gaps that must be addressed before practical deployment: quantitative UV–Vis and photoluminescence characterization, absolute quantum yield, haze and scattering, thickness and morphology mapping, accelerated UV aging, weathering resistance, toxicity assessment and crop-specific validation.