Synthesis, physical properties and OLED performance of azatetracenes

• Two new azatetracenes were synthesized and fully characterized.
• The monoazatetracene showed higher fluorescence than rubrene, while diazatetracenes show very low fluorescence.
• The OLED devices have been fabricated for the high fluorescent monoazatetracene dye.

Two novel azatetracenes: 5,7,8,9,10,12-hexaphenyl-2-azatetracene (2) and 1,4,6,11-tetraphenyl-2,3-diazatetracene (3), were synthesized and characterized. Comparing to Rubrene, 2 and 3 show blue-shifted absorptions. Interestingly, 2 displays stronger emission than rubrene in CH2Cl2, while the fluorescence of 3 is almost quenched. The electrochemical studies suggested that inserting sp2 N atoms into the backbone of tetracene could decrease both HOMO and LUMO orbital energies and more sp2 N atoms would result in lower HOMO orbital energy level. Since 2 has stronger fluorescence than rubrene, organic light emitting devices with 2 as emitters have been fabricated and the as-fabricated devices show a maximum current efficiency as high as 6.6 cd A−1. Our results indicated that the number of sp2 N atoms in the backbone of parent oligoacenes did have strong effect on the properties of as-resulted azaoligoacenes and this research could provide some guides to design and synthesize novel larger azaacenes.

Two novel azatetracenes have been synthesized through [4 + 2] cycloaddition reaction and shown different emission properties.Figure optionsDownload as PowerPoint slide