Organic light-emitting diodes with new dyes based on coumarin

Abstract

The results of studying the luminescent properties of organic light-emitting diodes based on new luminescent compounds containing a coumarin fragment are presented. The light-emitting diodes were fabricated by spin-coating and thermal evaporation in an argon atmosphere in a clean room. Measurements of the LED characteristics were carried out by optical spectroscopy, as well as by electrical methods. It has been experimentally shown that deposition of an OLED active layer based on luminescent compounds containing a coumarin core can lead to the formation of dimers, the luminescence spectra of which differ significantly from the corresponding spectra of the original materials in toluene. A variation in the structure of the compound leads to a change in both the current-voltage characteristics of the resulting device and the luminescence spectra. These changes appeared due to the difference in the electronic structure of these materials as well as due to different values of charge carrier mobilities and the potential barriers at the heterointerface with other OLED layers. The results obtained may serve as the basis for systematizing knowledge about the dependence of the properties of new luminescent materials, which include a coumarin core, on their structure. The developed structures can become prototypes for industrially produced light-emitting devices that specifically emit white light.

Keywords

• coumarin dyes
• organic light-emitting diodes
• electroluminescence
• structure-properties relationship
• current-voltage characteristics