Excitation mechanisms in dye-doped organic light-emitting devices
نویسندگان
چکیده
In an organic light-emitting device with a polymeric matrix concurrently doped with two different dyes, the photoluminescence ~PL! and electroluminescence ~EL! spectra are observed to be very different, with both dyes emitting in PL and only one in EL at room temperature. A simple model based on charge trapping and thermal excitation is introduced to explain this observation. The EL spectral change of a device at 77 K is consistent with this model. In addition, using the same model, the strong dependence of the EL efficiency ~but not PL! on the concentration of a single dye in an organic film can be understood. The materials used in this experiment are the polymer poly~9-vinylcarbazole! combined with electron transport molecules, and the dyes coumarin 47, coumarin 6, and Nile red. © 2001 American Institute of Physics. @DOI: 10.1063/1.1427746#
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