Abstract
Yellow emission is crucial in RGBY display technology and in fabricating physiologically-friendly low color temperature lighting source. Emitters with both wet- and dry-process feasibility are highly desirable to fabricate, respectively, high quality devices via vapor deposition and cost effective large area-size devices via roll-to-roll fabrication. We demonstrate in this report high-efficiency organic light-emitting diodes with a novel wet- and dry-process feasible yellow emitting iridium complex, bis[5-methyl-7-fluoro-5H- benzo(c)(1,5) naphthyridin- 6-one]iridium (picolinate). By spin coating, the device shows, at 1,000 cd /m2 for example, an external quantum efficiency (EQE) of 18.5% with an efficacy of 52.3 lm/W, the highest among all reported yellow devices via wet-process, while using vapor deposition, the EQE is 22.6% with a 75.1 lm/W efficacy, the highest among all dry-processed counterparts. The high efficiency may be attributed to the replacement of the hydrogen atom with a fluorine atom on a 2-substitutional site in the emitter to prevent dense molecular packing caused self-quenching and reduce radiationless deactivation rate, leading to a high quantum yield (71%).