Structural Engineering of Iridium(III) Phosphors with Imidazo[4,5-b]pyrazin-2-ylidene Cyclometalates for Efficient Blue Electroluminescence.

Autor: Yan J; Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG., Wu C; Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China., Tong KN; Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China., Zhou F; Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG., Chen Y; Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG., Pan Y; Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG., Xie G; The Institute of Flexible Electronics (Future Technologies), Xiamen University, Xiamen, 361005, China., Chi Y; Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG., Lau KC; Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, 999077, HONG KONG., Wei G; Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China.
Jazyk: angličtina
Zdroj: Small methods [Small Methods] 2024 Nov; Vol. 8 (11), pp. e2301555. Date of Electronic Publication: 2024 Jan 07.
DOI: 10.1002/smtd.202301555
Abstrakt: Iridium(III) complexes are particularly noted for their excellent potentials in fabrication of blue organic light-emitting diodes (OLEDs), but the severe efficiency roll-off largely hampered their practical applications. To reveal the underlying characteristics, three Ir(III) complexes, namely f-ct5c, f-ct5d, and f-ct11, bearing imidazo[4,5-b]pyrazin-2-ylidene cyclometalates are prepared and characterized in detail. Both f-ct5c and f-ct5d (also their mixture f-ct5mix) gave intensive blue emissions peaking at ≈465 nm with short radiative lifetimes of 1.76 and 2.45 µs respectively, in degassed toluene. Alternatively, f-ct11 with two 4-tert-butylphenyl substituents on each imidazo[4,5-b]pyrazin-2-ylidene entity, possessed a bluish-green emission (508 nm) together with an extended radiative lifetime of 34.3 µs in the dispersed PMMA matrix. Consequently, the resulting solution-processed OLED with f-ct11 delivered a maximum external quantum efficiency (EQE max ) of 6.5% with serious efficiency roll-offs. In contrast, f-ct5mix based device achieved a high EQE max of 27.2% and the EQE maintained at 23.0% of 1000 cd m -2 . Furthermore, the hyper-OLEDs with f-ct5mix as the sensitizer and v-DABNA as the terminal emitter afford narrowed emission with a considerably high EQE max exceeding 32%, affirming the potential of f-ct5mix to serve as both the emitter and sensitizer in OLEDs.
(© 2024 Wiley‐VCH GmbH.)
Databáze: MEDLINE
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