Enabling a 6.5% External Quantum Efficiency Deep-Blue Organic Light-Emitting Diode with a Solution-Processable Carbazole-Based Emitter

• Published in: Journal of physical chemistry. C 2018-10, Vol.122 (42), p.24295-24303
• Main Authors: Jou, Jwo-Huei, Li, Jheng-Lin, Sahoo, Snehasis, Dubey, Deepak Kumar, Kumar Yadav, Rohit Ashok, Joseph, Vellaichamy, Thomas, K. R. Justin, Wang, Ching-Wu, Jayakumar, Jayachandran, Cheng, Chien-Hong
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.8b07641

Highly efficient deep-blue emission is crucial to realize energy-efficient and high-quality display and solid-state lighting applications. A solution-processable deep-blue emitter is essential for producing cost-effective large-area devices via roll-to-roll fabrication. Here, we demonstrate a highly efficient solution-processable deep-blue organic light-emitting diode by utilizing a carbazole-based fluorescent emitter 6-((9,9-dibutyl-7-((7-cyano-9-(2-ethylhexyl)-9H-carbazol-2-yl)­ethynyl)-9H-fluoren-2-yl)­ethynyl)-9-(2-ethylhexyl)-9H-carbazole-2-carbonitrile (JV55). The resultant device showed a maximum external quantum efficiency (EQE) of 6.5% and an EQE of 5.5% at 100 cd/m2 with CIE coordinates of (0.16, 0.06). The optimized device showed a maximum EQE of 6.5%. Additionally, the deep-blue emission also realized a 101% color saturation according to the NTSC standard. The high efficiency may be attributed to engineering appropriate device architecture and enabling balanced carrier injection, effective host-to-guest energy transfer, the emissive layer having a very high quantum yield of 91%, utilizing a host with high triplet energy so as to confine exciton on the guest, and low doping concentration inhibiting efficiency roll-off due to concentration quenching.