Affiliation:
1. Department of Chemistry Education Graduate Department of Chemical Materials Institute for Plastic Information and Energy Materials and Sustainable Utilization of Photovoltaic Energy Research Center Pusan National University Busan 46241 Republic of Korea
2. Department of Chemistry Graduate School of Semiconductor Materials and Device Engineering and Graduate School of Carbon Neutrality Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Republic of Korea
3. Advanced Materials Division Korea Research Institute of Chemical Technology Daejeon 34114 Republic of Korea
Abstract
AbstractTwo green heteroleptic Ir(III) complexes are reported, namely, bis[5‐(2‐ethylhexyl)‐8‐trifluoromethyl‐5H‐benzo[c][1,5]‐naphthyridin‐6‐one](2‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)phenolate)iridium (III) (Ir(CF3BNO)2‐pop) and bis[5‐(2‐ethylhexyl)‐5H‐benzo[c][1,5]naphthyridin‐6‐one](2‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)phenolate)iridium (III) (Ir(BNO)2‐pop) for solution‐processed phosphorescent organic light‐emitting diodes (PHOLEDs). Both the Ir(III) complexes exhibit high external quantum efficiency (EQE) and intense green emission upon using poly(3,4‐ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) as a hole injection layer (HIL); Ir(CF3BNO)2‐pop based PHOLEDs perform better with an EQE of 23% and a current efficiency of 82 cd A−1 than Ir(BNO)2‐pop based PHOLEDs. In addition, to improve device operational lifetime, a crosslinkable HIL material, 9,9'‐(cyclohexane‐1,1‐diylbis(4,1‐phenylene))bis(N‐phenyl‐N‐(4‐(((4‐vinylbenzyl)oxy)methyl)phenyl)‐9H‐carbazol‐3‐amine) (CPCzDPAX‐1) is designed and synthesized. Device operational lifetimes of Ir(CF3BNO)2‐pop and Ir(BNO)2‐pop PHOLEDs incorporating the CPCzDPAX‐1 HIL show 14‐fold and 6‐fold improvement, compared to the corresponding devices incorporating the PEDOT:PSS HIL. To the best of the authors’ knowledge, this is the best device lifetime performance by using the combination of new Ir(III) complexes and HIL materials for solution‐processed green PHOLEDs.
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials