Abstract: To investigate effective means of improving the efficiency of organic light-emitting devices (OLEDs) by making full use of triplet emission,a phosphorescent material Pt (II) Octaethylporphine (PtOEP) is doped into polymer host polyspirobifluorene (Spiro) to allow radiative recombination of triplet excitons.The current and brightness characteristics of the devices are tested and the electroluminescent spectra are described.Both fluorescence and phosphorescence are observed,and an obvious increase in external quantum efficiency is realized compared to undoped devices when different phosphorescent dopant concentrations are tried.Thus,the phosphorescent emission from triplet excited states might be an effective way to increase the efficiency of OLEDs when the concentration of the phosphorescent dopant is properly controlled.

Key words: external quantum efficiency, triplet, organic light-emitting device