Funct. Mater. 2025; 32 (3): 323-347.

J-aggregates, highly ordered molecular assemblies, continue to attract significant attention in hybrid nanophotonic research owing to their strong absorption, efficient energy transfer, and pronounced fluorescence properties. When combined with nanostructured materials, their spectral properties – such as quantum yield, lifetime, and exciton dynamics – can be substantially modified. This review discusses various aspects of J-aggregates′ interactions with different nanostructured materials, focusing on their impact on the aggregates′ optical properties, particularly fluorescence. Strategies for enhancing the spectral response of J-aggregates in both liquid and solid media are highlighted.