TY - JOUR
T1 - Regioselective Syntheses of Imidazo[4,5-b]pyrazin-2-ylidene-Based Chelates and Blue Emissive Iridium(III) Phosphors for Solution-Processed OLEDs
AU - Yan, Jie
AU - Xue, Qin
AU - Yang, Hui
AU - Yiu, Shek-Man
AU - Zhang, Ye-Xin
AU - Xie, Guohua
AU - Chi, Yun
PY - 2022/6/13
Y1 - 2022/6/13
N2 - Six homoleptic Ir(III) complexes bearing imidazo-[4,5-b]pyrazin-2-ylidene chelates were successfully designed and synthesized. Narrowband blue emission (λmax = 466-485 nm) and broadened green emission (λmax = 518-532 nm) in degassed toluene solution with high photoluminescent quantum yields in the range of 75-81 and 45-48% were observed for ƒ-timpz, t2impz, and t2empz as well as m-timpz, t2impz, and t2empz, respectively. In addition, the tert-butylphenyl cyclometalate is more electron donating than N-phenyl cyclometalate and, hence, all tert-butylphenyl-substituted derivatives, that is, m- and ƒ-t2impz and m- and ƒ-t2empz, give more red-shifted emission in comparison to that of m- and ƒ-timpz. Moreover, solution-processed OLED with ƒ-t2empz (20 wt %) as the dopant gave electrophosphorescence at 474 nm with maximum external quantum efficiency (max. EQE) of 5.1%, while hyper-OLED with assistant sensitizer ƒ-t2empz (10 wt %) and the multi-resonance thermally activated delayed fluorescence emitter BCzBN (0.5 wt %) afforded narrowband emission centered at 485 nm and max. EQE up to 17.4%, confirming the high potential of this class of Ir(III) metal phosphors.
AB - Six homoleptic Ir(III) complexes bearing imidazo-[4,5-b]pyrazin-2-ylidene chelates were successfully designed and synthesized. Narrowband blue emission (λmax = 466-485 nm) and broadened green emission (λmax = 518-532 nm) in degassed toluene solution with high photoluminescent quantum yields in the range of 75-81 and 45-48% were observed for ƒ-timpz, t2impz, and t2empz as well as m-timpz, t2impz, and t2empz, respectively. In addition, the tert-butylphenyl cyclometalate is more electron donating than N-phenyl cyclometalate and, hence, all tert-butylphenyl-substituted derivatives, that is, m- and ƒ-t2impz and m- and ƒ-t2empz, give more red-shifted emission in comparison to that of m- and ƒ-timpz. Moreover, solution-processed OLED with ƒ-t2empz (20 wt %) as the dopant gave electrophosphorescence at 474 nm with maximum external quantum efficiency (max. EQE) of 5.1%, while hyper-OLED with assistant sensitizer ƒ-t2empz (10 wt %) and the multi-resonance thermally activated delayed fluorescence emitter BCzBN (0.5 wt %) afforded narrowband emission centered at 485 nm and max. EQE up to 17.4%, confirming the high potential of this class of Ir(III) metal phosphors.
KW - LIGHT-EMITTING-DIODES
KW - HIGH-EFFICIENCY
KW - ENERGY-TRANSFER
KW - COMPLEXES
KW - DOPANT
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U2 - 10.1021/acs.inorgchem.2c00750
DO - 10.1021/acs.inorgchem.2c00750
M3 - RGC 21 - Publication in refereed journal
SN - 0020-1669
VL - 61
SP - 8797
EP - 8805
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 23
ER -