Highly Efficient Yellow Organic Light Emitting Diode with a Novel Wet‐ and Dry‐Process Feasible Iridium Complex Emitter

Abstract

Yellow emission is crucial in RGBY display technology and in fabricating physiologically friendly, low color‐temperature lighting sources. 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 devices via roll‐to‐roll fabrication. Here, 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), are demonstrated. By spin coating, the device shows, at 1000 cd m−2, an external quantum efficiency (EQE) of 18.5% with an efficacy of 52.3 lm W−1, 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−1 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 to reduce radiationless deactivation rates, leading to a high quantum yield (71%).

Self‐Protective Room‐Temperature Phosphorescence of Fluorine and Nitrogen Codoped Carbon Dots

“…The introduction of fluorine atoms is a promising technique for improving hydrogen bonding interactions, which may provide steric protection around the phosphor and effectively enhance the stability of RTP emissions . Moreover, the strong electron withdrawing effect of fluorine atoms can lower of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels and reduce the energy gap between singlet (S 1 ) and triplet (T 1 ) states . So these results motivated us to carry out self‐protective RTP properties of CDs through the doping of fluorine and nitrogen.…”

Recent progress in the use of fluorescent and phosphorescent organic compounds for organic light-emitting diode lighting

“…71 As shown in Fig. 12, the synthesized material (78) substituting hydrogen in the 2 position with fluorine not only blocked molecular packing, but also decreased self-quenching, and provided a high PLQY of 71%.…”

Anomalously Long-Lasting Blue PhOLED Featuring Phenyl-Pyrimidine Cyclometalated Iridium Emitter

“…[7][8][9][10] Among various metal-containing phosphors, cyclometalated iridium(III) complexes are considered to be one of the most promising triplet emitters because of their versatile color tunability as well as high photoluminescence quantum yield (PLQY). [11][12][13][14][15][16][17] Efficient and stable red and green Ir-based phosphorescent materials have been successfully introduced into commercial OLED displays. Yet, practical applications of blue-emitting Ir(III) complexes still lag behind, mostly because of stability issues.…”