Synthesis, properties, and application as emitters in organic electroluminescence devices of quinacridone- and squarylium-dye-centred dendrimers

The UV-vis absorption and fluorescence spectra, solubility, and application as emitters in single-layer organic electroluminescence (EL) devices of novel quinacridone- and squarylium-dye-centred dendrimers (G(n)-QAs and G(n)-SQs) were examined. The respective dendrimers showed no remarkable differences in the UV-vis absorption (lambda(max)) and photoluminescence (PL) maxima (lambda(em)). The solubility of dendrimers drastically increased at higher generation. The EL maxima of G(n)-QAs and G(n)-SQs were observed at 522 and 710 nm, respectively. In the case of G(n)-QAs, the EL intensity under the fixed bias voltage decreased at higher generation due to a decrease in energy transfer from the host molecules to QA. Meanwhile, in the case of G(n)-SQs, the EL intensity increased upon higher generation because of increased current density and the improvement of concentration quenching.