Synthesis and photoelectric properties of fluorescence materials with electron donor-acceptor structures based on quinoxaline and pyridinopyrazine,carbazole,and diphenylamine derivatives
Four nitrogen heterocyclic fluorescent materials F1-F4 with electron donor-acceptor structures were synthesized based on quinoxaline and pyridinopyrazine derivatives,which were constructed by the condensation re-action of α-diketone with o-phenylenediamine and pyridine diamine.Their photophysical properties were studied in detail.By testing of the fluorescence lifetimes and low-temperature fluorescence/phosphorescence spectra of F1-F4,combined with density functional theory calculations,it can be concluded that all four molecules are fluorescent small materials.Compounds F1-F4 showed photoluminescence spectra with peaks at 529,464,568,and 507 nm,respectively,with photoluminescence quantum efficiencies(PLQYs)of up to 98.2％in toluene.Additionally,posi-tive solvatochromism was recorded from the emission spectra of four compounds in solvents with different polarities,further confirming their intramolecular charge transfer nature.Furthermore,the lifetimes of four compounds were 12.21,2.61,9.76,and 6.03 ns,respectively.To further explore the functionalized applications of these fluorescent molecules,they were doped as luminescent materials in organic light-emitting diodes(DF1-DF4).Among them,devices DF1 and DF3 achieved maximum current efficiencies of 13.38 and 11.98 cd·A-1 and maximum external quantum efficiencies of 4.8％and 4.5％with low-efficiency roll-off,which are related to the high PLQYs of mole-cules F1 and F3.
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