Room-Temperature Luminescence of Eosin Y and Phloxine B in Red- to Near-Infrared Optical Region

Room temperature luminescence of two far-red emitting dyes, Eosin Y and Phloxine B, embedded in polyvinyl alcohol films have been studied. Three types of luminescence emission, including prompt fluorescence, delayed fluorescence, and phosphorescence have been characterized. Fluorescence and delayed fluorescence of Eosin Y and Phloxine B appear in the orange-red optical region, whereas phosphorescence emissions cover far-red and near infra-red (NIR) spectral regions reaching over 800 nm. The millisecond phosphorescence lifetimes, high relative brightness of Eosin Y and Phloxine B, and unusually high phosphorescence anisotropy make them attractive optical room-temperature phosphorescence (RTP) materials in red to NIR spectral regions.