A novel bipolar carbazole/ phenanthroimidazole derivative for high efficiency nondoped deep-blue organic light-emitting diodes.

Abstract It is still a matter of worldwide continuous concern about how to obtain efficient, stable, pure blue light emitting materials and apply them in industrialized OLED devices. Here, a novel deep blue fluorescent material 2-(4'-(9 H -carbazol-9-yl)-[1,1′-biphenyl]-4-yl)-1-(4-methoxyphenyl)-1 H -phenanthro [9,10-d]imidazole(CzB-MOPPI) was firstly designed, synthesized and employed as emitters for deep-blue OLEDs. CzB-MOPPI, with carbazole as donor, twisted biphenyl bonded phenanthroimidazole which contains rigid plane structure as acceptor, exhibits high thermal stability with decomposition temperature (T d) of 480 °C. Weak donor carbazole unit and twist biphenyl both make the compound emit less red shift meanwhile maintain in deep blue region. The non-doped OLEDs based on the CzB-MOPPI as emitter show maximum emission at 435 nm, maximum luminance of 6450 cd/m2, maximum current efficiency (CE) of 3.34 cd/A. The chromaticity coordinate is (0.16, 0.08) which is extremely close to the NTSC standard blue. In Particular, the devices show an impressive external quantum efficiency (EQE) as high as 5.97%. Graphical abstract Image 1 Highlights • A donor-acceptor type deep blue fluorescent material was firstly designed and synthesized. • Compound exhibits high thermal stability and bipolar properties. • OLED devices were fabricated, showing deep blue emission and impressive high EQE of 5.97%. [ABSTRACT FROM AUTHOR]