Aggregation-induced emission
Aggregation-induced emission is a phenomenon in which certain organic luminophores exhibit stronger emission of light in their aggregated or solid state compared to when they are in solution. This counterintuitive behavior contrasts with most organic compounds, which typically show reduced photoemission in the solid state due to processes like aggregation-caused quenching. AIE is primarily attributed to restricted molecular motion in the aggregated state, which suppresses nonradiative energy dissipation and enhances fluorescence efficiency. The increase of fluorescence emission intensity was also observed upon restriction of molecular motion due to host-guest interactions and viscosity increase, which is not a common behavior of such host-guest complexes.