Synthesis and Electroluminescent Properties of OLED Green Dopants Based on BODIPY Derivatives

Abstract

Organic light-emitting diodes (OLEDs) based on the small organic molecules have gained remarkable attention for display and solid-state lighting applications over the last few years due to their well-defined molecular structures, facile syntheses and modifications, and specific structure-property correlations. One approach that has been used to improve the efficiency of the OLED devices in term of brightness and stability is the introducing of the highly fluorescent organic guest dopants into the host materials to obtain the full color display. Therefore, there is still a need for the development of new dopants with good color purity, stability and high efficiency. Difluoroboradiaza-s-indacene (BODIPY) represents an outstanding class of fluorophore with high quantum yield, large molar absorption coefficient, high chemical, thermal and photophysical stability. The development of new BODIPY derivatives has become a booming of research due to their potential applications in luminescent devices, chemical sensors, biological labeling, and photovoltaic cells. Major efforts have been devoted to obtain the welldesigned BODIPY structures by modifying of the pyrrole core, fusing some aromatic rings to the BODIPY core, and replacing the 8-carbon atom with a nitrogen atom to form aza-BODIPY. The incorporation of boron element into the π-conjugated framework may lead to the appearance of unique electronic and photophysical properties. Recently, we have successfully explored some green dopants based on arylamine 2,3-disubstituted bithiophene derivatives for OLEDs. In the course of our ongoing studies, herein we wish to report the novel green dopants based on BODIPY and two different arylamine moieties with good overall performance in the multilayer device (Figure 1). In the design of the target molecules 5a–b (Figure 1), the outstanding fluorescent BODIPY core was fused with different arylamine moieties which were expected to enhance the light emitting efficiency through the extension of the