Fabrication of Colorless Organic Materials Exhibiting White Luminescence Using Normal and Excited-State Intramolecular Proton Transfer Processes

Organic, white luminescent materials were fabricated using a mixture of proton-transfer and nonproton-transfer fluorophores. 2'-Methoxy and 2'-hydroxy derivatives of 2-phenylimidazo[1,2-a]pyridine (PIP) have similar UV-absorption properties; however, they exhibit mechanistically different luminescence respectively ascribable to the normal (∼420 nm) and excited-state intramolecular proton transfer processes (∼530 nm) in the solid state. UV-irradiation of mixed solids excites both components concurrently and results in efficient white luminescence composed of two independent emissions without involving energy transfer process. White luminescent solids are easily transformed into vapor-deposited films under mild conditions, and a colorless and transparent thin film by dissolving in PMMA.