LAUSR

White light-emitting phenothiazine-poly(dimethylsiloxane) (PTZ–PDMS) composites are formed by a photooxidation reaction. The oxidized PTZ species, i.e., PTZ cation radicals and dication species, are created by electron transfer from the PTZ molecules to PDMS under UV irradiation. In situ UV– vis and electron spin resonance (ESR) spectroscopies are carried out after UV exposure of PTZ–PDMS, and the results provide evidence for the spontaneous ionization of PTZ. The spectral changes indicate the formation of PTZ•+ (radical cation) and PTZ2+ (dication) within the PDMS matrix. Moreover, a combination of PTZ, PTZ•+, and PTZ2+, together with the PDMS matrix, show an unexpected emission of white light with Commission Internationale de L'Eclairage coordinates of 0.34 and 0.32, which are close to those of pure white light. These findings potentially offer a new route and strategy for the development of flexible white light-emitting materials.