Photoinduced change of dielectric permittivity in molecular doped polymer layer

Abstract

We demonstrate a large photoinduced change of dielectric permittivity due to the charge separated (CS) state of an electron donor-acceptor linked molecule, 6- [4′ -(N,N -diphenylamino)phenyl]-3-ethoxycarbonylcoumarin (DPA-CM), doped in a polymethylmethacryrate (PMMA) matrix. Dielectric permittivity of DPA-CM in PMMA film increases from 4.1 to 7.5 under photoirradiation. Electron spin resonance spectra of the films measured under photoirradiation clearly show the formation of the CS state of DPA-CM in PMMA matrix. The origin of the photoinduced change of the dielectric permittivity is ascribed to the realignment of dipole of the CS state of DPA-CM. © 2009 American Institute of Physics.