cm4024309_si_002.cif (34.16 kB)
Rational Design of Strongly Blue-Emitting Cuprous Complexes with Thermally Activated Delayed Fluorescence and Application in Solution-Processed OLEDs
dataset
posted on 2013-10-08, 00:00 authored by Xu-Lin Chen, Rongmin Yu, Qi-Kai Zhang, Liu-Jiang Zhou, Xiao-Yuan Wu, Qing Zhang, Can-Zhong LuA new series of strongly greenish-blue
to blue emitting Cu(NN)(POP)+ (POP = bis[2-(dipenylphosphino)phenyl]ether)
complexes containing
N-linked 2-pyridyl pyrazolate diimine ligands [Cu(pypz)(POP)]BF4 (1), [Cu(pympz)(POP)]BF4 (2), and [Cu(pytfmpz)(POP)]BF4 (3) (pypz =
1-(2-pyridyl)pyrazole, pympz = 3-methyl-1-(2-pyridyl)pyrazole, and
pytfmpz = 3-trifluoromethyl-1-(2-pyridyl)pyrazole) have been designed
and synthesized. Their structural, electrochemical, and photophysical
properties have been characterized. The complexes 1–3 exhibit high photoluminescence quantum yields (PLQYs) at
room temperature both in nitrogen-saturated CH2Cl2 (up to 45%) and in neat solid (up to 87%), which are comparable
to the reported highest values for the cuprous complexes. The temperature
dependence of spectroscopic properties and emission decay behaviors
reveal the presence of two thermally equilibrated emitting states.
At temperatures below 150 K, the lowest triplet state (T1) is the predominant emitting state resulting in the typical phosphorescence
with the emission decay times in the order of hundreds of microseconds.
However, at ambient temperature, the lowest singlet state (S1), which lies only about 0.17–0.18 eV above the T1 state, is populated thermally and in turn generates efficient thermally
activated delayed fluorescence (TADF), and the emission decay times
are reduced dramatically to, e.g., 12.2 μs for 2. Solution-processed OLEDs containing 1–3 in the emissive layer demonstrated excellent device performances
by taking advantage of the singlet harvesting mechanism, among which
the electroluminescent device using 3 shows a peak external
quantum efficiency (EQE) of 8.47%, a peak current efficiency (CE)
of 23.68 cd/A, and a maximum brightness of 2033 cd/m2.
History
Usage metrics
Categories
Keywords
emission decay timestemperature dependencetriplet stateOLEDelectroluminescent deviceEQEpyridylsinglet statephotophysical propertiesambient temperatureThermally Activatedphotoluminescence quantum yields150 Kemission decay behaviorsTADFT 1 statequantum efficiencyPLQYemissive layerCHsinglet harvesting mechanismdevice performancescuprous complexesCuspectroscopic propertiesCEPOPRational Designroom temperature
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC