Electroluminescence from triplet excited states of benzophenone derivatives

This paper investigated electroluminescent (EL) characteristics of multilayer organic light emitting diodes (LEDs) utilizing poly(methylmethacrylate) films containing typical phosphorescent benzophenone (BP) derivatives such as BP or 4,4'-dichlorobenzophenone as an emitting layer. The EL spectra exhibit agree well with the phosphorescence spectra of emitting materials at a low temperature. Combined analysis of temperature dependence of EL intensity, EL spectra, and EL decay time indicate that the EL of these LEDs originates from the triplet excited states of the BP derivatives.