Electromodulation of Luminescence in Organic Photoconductors

Abstract

The modulating electric field effect on the luminescence (EFEL) of a series of organic photoconductors is observed and results discussed in terms of various theoretical models. A physical interpretation of EFEL is proposed on the basis of the Onsager and macrotrap models. It is found that EFEL is, in major part, due to the field‐induced change in the hopping rate of optically excited charge carriers between localized sites (microtraps) forming an extended defect (macrotrap) for molecular solids with excited states characteristic of neutral Frenkel excitons, whereas the field modification of the carrier diffusion in the separation process (Onsager model) seems to be of crucial importance for the photoconductors revealing low‐energy charge‐transfer excitons formed upon optical excitation.