Efficient non-doped deep blue organic light emitting diodes with high external quantum efficiency and a low efficiency roll-off based on donor-acceptor molecules

• Novel emissive molecules containing phenanthroimidazole, triphenylamine, carbazole and pyrene units are developed.
• Deep blue emission is exhibited by these fluorescent materials.
• High thermal stability of materials and low operating voltage of device are observed.
• Non-doped OLEDs are constructed with high efficiency and low roll-off.

Two phenanthroimidazole derivatives containing triphenylamine, carbazole and pyrene units were designed and synthesized. Highly efficient non-doped deep blue organic light emitting diodes (OLEDs) were fabricated by using these materials as emissive layer. The non-doped devices demonstrated high efficiency (4.24 cd/A, 3.67 lm/W, 4.66%), low efficiency roll-off at higher current densities, and stable deep blue emissions with CIEy around 0.10, which are excellent results for deep-blue OLED devices. This study reveals that the combination of phenanthroimidazole and donor-linker-acceptor strategy has a great potential for developing high performance deep-blue OLEDs.