Benzoisoquinoline-1,3-dione acceptor based red thermally activated delayed fluorescent emitters

Article abstract of DOI:10.1016/j.dyepig.2017.05.036

A strong electron deficient moiety, benzoisoquinoline-1,3-dione, was applied as an electron acceptor of donor-acceptor type thermally activated delayed fluorescent (TADF) emitters. The connection of the benzoisoquinoline-1,3-dione acceptor moiety with a d

Full text of DOI:10.1016/j.dyepig.2017.05.036

Accepted Manuscript
Benzoisoquinoline-1,3-dione acceptor based red thermally activated delayed
fluorescent emitters
Ju Hui Yun, Jun Yeob Lee
PII:
S0143-7208(17)30042-6
10.1016/j.dyepig.2017.05.036
DYPI 5998
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 7 January 2017
Revised Date: 16 May 2017
Accepted Date: 17 May 2017
Please cite this article as: Yun JH, Lee JY, Benzoisoquinoline-1,3-dione acceptor based red thermally
activated delayed fluorescent emitters, Dyes and Pigments (2017), doi: 10.1016/j.dyepig.2017.05.036.
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ACCEPTED MANUSCRIPT
Benzoisoquinoline-1,3-dione acceptor based red thermally activated delayed
fluorescent emitters
Ju Hui Yun, Jun Yeob Lee*
School of Chemical Engineering, Sungkyunkwan University
2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 440-746, Korea
Fax: (+) 82-31-299-4716
E-mail: leej17@skku.edu
*
To whom correspondence should be addressed
Abstract
A strong electron deficient moiety, benzoisoquinoline-1,3-dione, was applied as an electron acceptor of
donor-acceptor type thermally activated delayed fluorescent (TADF) emitters. The connection of the
benzoisoquinoline-1,3-dione acceptor moiety with a dimethylacridine donor moiety prepared 6-(9,9-
dimethylacridin-10(9H)-yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione
and
5-(9,9-
dimethylacridin-10(9H)-yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione as red TADF emitters
by strong electron deficiency of the benzoisoquinoline-1,3-dione acceptor. Device optimization of the
red TADF emitters based on the delayed fluorescent behaviour of the red TADF emitters could offer
high quantum efficiency of 11.2% in the red TADF devices.
Key words : red device, delayed fluorescence, quantum efficiency, benzoisoquinoline-1,3-dione
1

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Introduction
The demand for high efficiency organic light-emitting diodes (OLEDs) is getting stronger as the
power consumption is one of key issues of OLEDs. Although there have been great advances made in
the development of low power OLEDs, the power consumption of the OLEDs is still a challenging
issue.
The accomplishment of the low power consumption in the OLEDs was mainly made by high
efficiency phosphorescent emitters which show high external quantum efficiency (EQE) close to
30%[1-5]. Red and green phosphorescent emitters already applied in commercial OLED products were
main contributors to the development of low power consuming OLEDs[2,5]. However, the high price
of the phosphorescent emitters by Ir metal was a hurdle to full utilization of the phosphorescent
emitters in mass production. One approach to overcome the cost issue of the phosphorescent emitters is
to use high efficiency emitters made up of pure organic moieties without any precious metal.
E-type delayed fluorescent emitters which are known as thermally activated delayed fluorescent
(TADF) emitters can be a candidate as the pure organic based high efficiency emitters[6-11]. There has
been a big progress of EQE of the TADF emitters for the last three years and the best EQE of the
TADF device was as high as 30% in the green device[7,12-15]. As a result, the TADF emitters are
promising as the organic type high efficiency emitters replacing phosphorescent emitters. However, the
EQE of the red TADF device is not as high as that of green or blue devices[6-11,16-18] although high
EQE of 17.5% (HAP-3TPA)[11] was known in the red device, which is mostly due to lack of strong
electron acceptors for the red TADF emitters. Therefore, new strong electron accepting moieties are
needed to reach the EQE level of the green and blue TADF devices.
In this work, an imide type electron deficient moiety, benzoisoquinoline-1,3-dione (BIQ), was used
as an electron acceptor of a TADF emitter and was used to synthesize 6-(9,9-dimethylacridin-10(9H)-
yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (6AcBIQ) and 5-(9,9-dimethylacridin-10(9H)-
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yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (5AcBIQ) as red TADF emitters. Preparation,
characterization, and device application of the TADF emitters were comprehensively covered. The
6AcBIQ red TADF emitter exhibited high EQE of 11.2%, red color coordinate of (0.55, 0.44), and
peak wavelength of 597 nm.
Experimental
General information
4
-Bromo-1,8-naphthalic anhydride was purchased from TCI Co. and aniline was supplied from Sigma-
Aldrich Co.. 3-Bromo-1,8-naphthalic anhydride and sodium tert-butoxide were products of Alfa Aesar.
,9-Dimethyl-9,10-dihydroacridine, tri-tert-butylphosphine, tris(dibenzylideneacetone) dipalladium (0),
9
palladium (II) acetate were provided from P&H tech Co.. Molecular sieve, magnesium sulfate, ethanol,
toluene, methylene chloride, ethyl acetate, and n-hexane from Duksan Sci. Co. were used without
further purification.
The ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectra were obtained using
Jasco V-730 UV spectrophotometer and Perkin Elmer LS 55 luminescence spectrometer, respectively.
Electrochemical analysis was carried out using Ivium Vertex with 0.1 M tetrabutylammonium
perchlorate electrolyte in acetonitrile, Ag reference and Pt counter electrodes. Ferrocene was an internal
standard material of the electrochemical measurement. Absolute PL quantum yields (PLQYs) of
materials were measured using a doped solid film with a Hamamatsu Quantaurus-QY C11347-11
spcetrometer.
Synthesis
Synthetic scheme of 6AcBIQ and 5AcBIQ compounds is described in Scheme 1.
6-Bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione
4-Bromo-1,8-naphthalic anhydride (3.0 g, 10.83 mmol) was dissolved in distilled ethanol (150 mL).
3

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Aniline (1.20 mL, 12.99 mmol) was added to the solution, and then the solution was refluxed overnight
under nitrogen. The solution was cooled and the precipitate was filtered with no further purification.
1
The product was an ivory powder (2.8 g, yield 74%)[19,20]. H NMR (500 MHz, DMSO-d ):δ 8.637-
6
8.590 (m, 2H), 8.363 (d, 1H, J=8.0 Hz), 8.277 (d, 1H, J=8.0 Hz), 8.05 (t, 1H, J=7.75 Hz), 7.533 (t, 2H,
+
J=8.0 Hz), 7.471 (t, 1H, J=7.25 Hz), 7.396 (d, 2H, J=7.0 Hz). MS (m/z): found, 354.0 ([M + H] );
Calcd. for C H BrNO , 352.18.
1
8
10
2
6-(9,9-Dimethylacridin-10(9H)-yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (6AcBIQ)
6-Bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (0.7 g, 1.99 mmol), 9,9-dimethyl-9,10-
dihydroacridine (0.46 g, 2.20 mmol), sodium tert-butoxide (0.38 g, 3.95 mmol), and
tris(dibenzylideneacetone)dipalladium (0) (0.05 g, 0.05 mmol) were dissolved in toluene (40 ml). Tri-
tert-butylphosphine (0.08 g, 0.40 mmol) was added into the solution, and then the solution was refluxed
overnight under nitrogen. The reaction mixture was cooled and extracted with methylene chloride and
distilled water. The organic layer was dehydrated with magnesium sulfate and the solvent was
evaporated. The crude powder was purified by column chromatography with ethyl acetate and n-
1
hexane. An orange powder was obtained as a product after purification (0.62 g, yield 65%)[21,22]. H
NMR (500 MHz, DMSO-d ):δ 8.748 (d, 1H, J=8.0 Hz), 8.556 (d, 1H, J=8.5 Hz), 8.001-7.957 (m, 2H),
6
7
7
1
1
1
.846 (t, 1H, J=7.75 Hz), 7.635 (d, 2H, J=7.5 Hz), 7.567 (t, 2H, J=7.5 Hz), 7.497 (t, 1H, J=7.25 Hz),
.445 (d, 2H, J=8.5 Hz), 6.941 (t, 2H, J=8.25 Hz), 6.891 (t, 2H, J=8.5 Hz), 5.909 (d, 2H, J=8.0 Hz),
1
3
.820 (s, 3H), 1.725 (s, 3H). C NMR (125 MHz, DMSO-d ):δ 163.47, 163.18, 143.09, 139.53, 135.98,
6
32.29, 131.31, 130.99, 130.25, 129.98, 129.47, 129.32, 129.09, 128.93, 128.53, 128.29, 126.78,
26.37, 124.13, 123.38, 121.06, 113.53, 35.64, 33.06, 32.46. MS (m/z): found, 481.1917 ([FAB+]);
Calcd. for C H N O , 481.1916.
3
3
24
2
2
5-Bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione
5-Bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione was synthesized according to the
4

ACCEPTED MANUSCRIPT
synthetic method of 6-bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione except that the
reactant was 3-bromo-1,8-naphthalic anhydride (1.0 g, 3.61 mmol). The reaction mixture was extracted
with methylene chloride and distilled water, and dehydrated with magnesium sulfate. A white powder
was obtained as a product after purification by column chromatography with methylene chloride and n-
1
hexane (0.65 g, yield 51%). H NMR (300 MHz, DMSO-d ):δ 8.813 (s, 1H), 8.513-8.441 (m, 3H),
6
7.938 (t, 1H, J=7.8 Hz), 7.551-7.460 (m, 3H), 7.38 (d, 2H, J=8.4 Hz). MS (m/z): found, 354.0 ([M +
+
H] ); Calcd. for C H BrNO , 352.18.
18
10
2
5-(9,9-Dimethylacridin-10(9H)-yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (5AcBIQ)
5-(9,9-dimethylacridin-10(9H)-yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione was synthesized
by
benzo[de]isoquinoline-1,3(2H)-dione.
0.65 g, 1.85 mmol) was used instead of 6-bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione
and palladium (II) acetate (0.02 g, 0.06 mmol) was used instead of
the
same
synthetic
method
of
6-(9,9-dimethylacridin-10(9H)-yl)-2-phenyl-1H-
5-Bromo-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione
(
tris(dibenzylideneacetone)dipalladium (0). The crude product was purified by column chromatography
1
using methylene chloride instead of ethyl acetate (0.55 g, yield 62%). H NMR (500 MHz, DMSO-
d6):δ 8.692 (s, 1H), 8.614-8.588 (m, 2H), 8.302 (s, 1H), 8.003 (t, 1H, J=7.75 Hz), 7.572-7.524 (m, 4H),
7.471 (t, 1H, J=8.0 Hz), 7.430 (d, 2H, J=8.5 Hz), 6.999-6.943 (m, 4H), 6.204 (d, 2H, J=9.5 Hz), 1.688
1
3
(
s, 6H). C NMR (125 MHz, DMSO-d ):δ 163.52, 163.07, 140.06, 139.07, 136.83, 135.92, 134.33,
6
1
1
4
33.68, 133.09, 131.36, 129.98, 129.06, 128.89, 128.28, 127.99, 127.40, 126.60, 126.36, 125.74,
22.93, 121.10, 113.81, 35.65, 31.34. MS (m/z): found, 481.1910 ([FAB+]); Calcd. for C H N O ,
33
24
2
2
81.1916.
Device fabrication and measurements
Device structure and device fabrication process of red TADF devices were described below.
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ITO/PEDOT:PSS (60 nm)/TAPC (20 nm)/mCP (10 nm)/ CBP:TPBI:red TADF emitter (25 nm, 5%
doping)/TSPO1 (5 nm)/TPBI (40 nm)/LiF (1.5 nm)/Al (200 nm)
ITO
represents
indium
tin
oxide,
TAPC
PEDOT:PSS
is
poly(3,4-
ethylenedioxythiophene):poly(styrenesulfonate),
is
4,4’-cyclohexylidenebis[N,N-bis(4-
methyphenyl)benzenamine], mCP is 1,3-bis(N-carbazolyl)benzene, CBP is 4,4'-di(9H-carbazol-9-yl)-
,1'-biphenyl and TPBI is 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene, TSPO1 is
diphenyl(4-(triphenylsilyl)phenyl)phosphine oxide. Emitting layer of the TADF devices was 5%
AcBIQ or 5AcBIQ doped CBP:TPBI. PEDOT:PSS was coated on the ITO substrate by spin coating
1
6
and other organic layers were layered by vacuum evaporation. Device characterization was performed
using CS1000 spectroradiometer and Keithley 2400 source meter.
Results and discussion
The electron deficient BIQ moiety has two carbonyl units conjugated to a naphthalene backbone
structure to allow electron accepting character and low emission energy for red emission. The two
carbonyl units are responsible for the strong electron accepting property and the extended conjugation
structure is for the long wavelength emission. A strong dimethylacridine donor was combined with the
BIQ acceptor for small singlet-triplet energy splitting (∆E ) and red-shift of emission wavelength.
ST
Two BIQ based acceptors with different substituent positions of 5- and 6- were prepared to investigate
the effect of substitution position on the material and device characteristics. Synthesis of the 6AcBIQ
and 5AcBIQ started from brominated naphthalic anhydride, which reacted with aniline to synthesize
the BIQ core. The brominated BIQ core was modified with dimethylacridine to prepare the final
6AcBIQ and 5AcBIQ products.
The 6AcBIQ and 5AcBIQ were reviewed as TADF emitters by figuring out the molecular orbital
represented by the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular
6

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orbital (LUMO) in Figure 1. B3LYP functional 6-31G basis set embedded in the Gaussian package
was used to calculate the molecular orbital. The BIQ electron acceptor and acridine donor isolated the
HOMO on the acridine and LUMO on the BIQ. In particular, the perpendicular orientation of the
acridine donor to the BIQ acceptor plane by steric hindrance between hydrogen of acridane and BIQ
resulted in the isolation of the HOMO and LUMO. The HOMO and LUMO pictures of 6AcBIQ and
5AcBIQ were of little difference.
The similar separation of the HOMO and LUMO from molecular calculation resulted in the similar
HOMO and LUMO levels estimated from electrochemical cyclic voltammetry measurements in Figure
. The HOMO/LUMO values of 6AcBIQ and 5AcBIQ were -5.89/-3.89 eV and -5.85/-3.85 eV,
2
respectively. The substitution position of the BIQ acceptor moiety had nothing to do with the
HOMO/LUMO levels of the 6AcBIQ and 5AcBIQ. The LUMO level of the BIQ compounds was
relatively deep compared to that of other TADF emitters, demonstrating strong electron accepting
character of the BIQ acceptor[11, 23, 24]. The calculated HOMO/LUMO level of the BIQ moiety was -
6.47/-2.39 eV.
PL behaviour 6AcBIQ and 5AcBIQ was analysed by recording fluorescence and phosphorescence in
Figure 3. Fluorescence spectra were collected at room temperature and phosphorescence spectra were
gathered at 77k after delay time of 100 µs. Broad charge transfer (CT) emission spectra with a peak
emission wavelength of 570 nm were commonly observed in the 6AcBIQ and 5AcBIQ emitters. From
the onset of the fluorescence spectra, singlet energy values of 2.38 and 2.41 eV in the 6AcBIQ and
5AcBIQ, respectively, were determined. The origin of fluorescence was CT emission in both 6AcBIQ
and 5AcBIQ, and that of phosphorescence was also CT emission. This experimental result was
coincided with the electronic transition calculation results proposing CT excited state for the lowest
triplet excited state. The onset wavelength of the phosphorescent spectra provided triplet energy values
of 2.30 and 2.32 eV in the 6AcBIQ and 5AcBIQ emitters. ∆E values of 6AcBIQ and 5AcBIQ from
ST
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the PL data were 0.08 and 0.09 eV, respectively. The ∆E of the two emitters was less than 0.1 eV,
ST
which suggests the potential of 6AcBIQ and 5AcBIQ as up-converting emitting materials.
The up-conversion process from triplet excited state to singlet excited state was analysed by absolute
PL quantum yield (PLQY) and delayed fluorescence decay of the emitters doped in the host materials.
Absolute PLQYs of 6AcBIQ and 5AcBIQ were 38.9 and 21.5% under nitrogen, while they were 16.8
and 5.2% without nitrogen. The PLQY of 6AcBIQ was higher than that of 5AcBIQ with and without
nitrogen, suggesting high radiative transition probability of 6AcBIQ. The 6- position modification of
the BIQ backbone was advantageous for light emission by linear orientation of the donor and acceptor
unit, while the 5- position modification of the BIQ backbone was disadvantageous by kinked
arrangement of the donor and acceptor. Transient PL decay data provided further information about the
prompt fluorescence and delayed fluorescence. The transient PL data in Figure 4 compared PL decay
of 6AcBIQ and 5AcBIQ doped in a mixed host of CBP and TPBI. The PL data of the two materials
agreed each other, stating similar triplet to singlet up-conversion behaviour through delayed
fluorescence. In general, the up-conversion by TADF process relies on the ∆E of the emitters. In the
ST
case of the 6AcBIQ and 5AcBIQ emitters, it seems that the similar ∆E below 0.1 eV brought about
ST
the same TADF behaviour. Excited state lifetime values of the TADF emission was 20.3 and 23.4 µs in
the 6AcBIQ and 5AcBIQ emitters. All material related data are summarized in Table 1.
The transient PL behaviour of 6AcBIQ was further studied by recording temperature dependent PL
decay at different temperatures (Figure 5). As the delayed fluorescence of 6AcBIQ TADF emitter is
activated by thermal energy, gradual increase of the delayed PL intensity according to temperature was
apparent in the PL decay data, confirming that the origin of delayed fluorescence is TADF.
The PL characterization results of 6AcBIQ and 5AcBIQ suggested that they would serve as TADF
emitters in the devices. As the peak wavelength of the PL emission of 6AcBIQ and 5AcBIQ was in
between 578 nm and 601 nm, they can be regarded as red TADF emitters. Therefore, they were applied
as red emitters in the TADF devices by doping in the mixed host of CBP and TPBI. Device data at 5%
8

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doping concentration were used to characterize the device performances of the 6AcBIQ and 5AcBIQ
devices. Device data of the 6AcBIQ and 5AcBIQ are displayed in Figure 6 and 7. The current density
of the two devices was quite similar because the emitters were doped in the same host material at the
same doping concentration and had similar HOMO/LUMO levels. However, the luminance was
relatively high in the 6AcBIQ device due to better quantum efficiency of the device.
The better exciton generation efficiency of the 6AcBIQ device was confirmed by EQE of the
6AcBIQ and 5AcBIQ devices in Figure 7. The maximum EQE of the 6AcBIQ device was 9.5%, which
was much higher than 4.6% of the 5AcBIQ device. The EQE was more than doubled just by changing
the substitution position of the acridine donor to the BIQ acceptor core. The EQE is closely associated
with the PLQY of the emitters, and the relative high EQE of the 6AcBIQ device is also caused by
relatively higher PLQY of 6AcBIQ than that of 5AcBIQ.
Electroluminescence (EL) spectra of the 6AcBIQ and 5AcBIQ devices in Figure 8 demonstrate that
the two TADF emitters are red emitters with a peak wavelength around 600 nm. Although the peak
wavelength was slightly red-shifted in the 6AcBIQ, the EL spectra were quite similar. The EL emission
behaviour was in agreement with the PL emission of the emitters. Color coordinates of the 6AcBIQ and
5AcBIQ were (0.56, 0.44) and (0.54, 0.46), respectively.
The EQE of the 6AcBIQ was further studied by changing the host material from the CBP:TPBI host
to a bipolar host material[25]. A bipolar host material reported in the literature, 3-(3-(9H-carbazol-9-
yl)phenyl)furo[2,3-b:5,4-b']dipyridine (mCPPFP)[15], was used to enhance the EQE of the 6AcBIQ
emitters. The EQE of the mCPPFP:6AcBIQ was 11.2% as shown in Figure 9. The EQE was reduced
according to doping concentration and maximum EQE was obtained at low doping concentration.
Although the EQE was reduced at high doping concentration, the EL spectra moved to long wavelength
and color purity was improved. Device characteristics of the red TADF devices are summarized in
Table 2.
9

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Conclusions
In summary, a benzoisoquinoline-1,3-dione based acceptor, BIQ, was developed as a strong electron
acceptor for the material design of red TADF emitters. 6AcBIQ and 5AcBIQ emitters derived from the
BIQ acceptor functioned as the red TADF emitters by activating delayed fluorescence transition
induced by small ∆E . 6AcBIQ performed better than 5AcBIQ by achieving high EQE of 11.2% as a
ST
red TADF emitter. Although the EQE value is not as high as the state of the art red TADF devices,
further design and device engineering may improve the EQE further.
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for blue phosphorescent organic light-emitting diodes. Dyes and Pigments 2016;134:285-90.
24] Im YR, Kim MG, Cho YJ, Seo JA, Yook KS, Lee JY. Molecular Design Strategy of Organic
Thermally Activated Delayed Fluorescence Emitters. Chem. Mater. 2017;29:1946-63.
25] Yoo SG, Jeon SK, Hwang SH, Lee JY. A strong hole transport type host material for high
quantum efficiency blue phosphorescent organic light-emitting diodes. J. Ind. Eng. Chem. 2015;32;72-
[
[
6.
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List of tables
Table 1. Photophysical properties of 6AcBIQ and 5AcBIQ
Table 2. Device characteristics of 6AcBIQ and 5AcBIQ
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List of figures
Scheme 1. Synthetic scheme of 6AcBIQ and 5AcBIQ
Figure 1. HOMO and LUMO distribution of (a) 6AcBIQ and (b) 5AcBIQ
Figure 2. CV curves of 6AcBIQ and 5AcBIQ
Figure 3. UV-Vis, fluorescence and phosphorescence spectra of (a) 6AcBIQ and (b) 5AcBIQ
Figure 4. Transient PL curves of 6AcBIQ and 5AcBIQ
Figure 5. Transient PL curves of 6AcBIQ at different temperatures
Figure 6. Current density-voltage-luminance plots of 6AcBIQ and 5AcBIQ at 5% doping concentration
Figure 7. Quantum efficiency plots of 6AcBIQ and 5AcBIQ devices against luminance
Figure 8. EL spectra of 6AcBIQ and 5AcBIQ devices
Figure 9. Quantum efficiency-luminance plots of the 6AcBIQ devices with a mCPPFP host according
to doping concentration
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Table 1. Photophysical properties of 6AcBIQ and 5AcBIQ
[
a]
Excited state
lifetime
PLQY (%)
N2
HOMO/LUMO
eV)
ES/ET
(eV)
ΔEST
(eV)
(
O2
21.5
5.2
(μs)
6
5
AcBIQ
AcBIQ
-5.89/-3.89
-5.85/-3.85
2.38/2.30
2.41/2.32
0.08
0.09
38.9
16.8
20.3
23.4
[
a] PLQYs measured in film
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Table 2. Device characteristics of 6AcBIQ and 5AcBIQ
Maximum EQE
%)
Maximum PE
EQE
(%)
PE
(LmW )
CIE (x,y)
-1
[a]
-1 [b]
(
(LmW )
6
AcBIQ
AcBIQ
0.56, 0.44
0.54, 0.46
0.55, 0.44
9.5
4.6
18.7
9.9
3.4
3.0
5
1.0
4.4
0.8
3.5
[
c]
6AcBIQ
11.2
23.0
-
2
[
[
[
a] External quantum efficiency measured at 1000cdm
-2
b] Power efficiency measured at 1000cdm
c] Device performances of mCPPFP:6AcBIQ at 3% doping concentration
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Scheme 1. Synthetic scheme of 6AcBIQ and 5AcBIQ
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LUMO
HOMO
(a)
(b)
Figure 1. HOMO and LUMO distribution of (a) 6AcBIQ and (b) 5AcBIQ
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Figure 2. CV curves of 6AcBIQ and 5AcBIQ
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(a)
(b)
Figure 3. UV-Vis, fluorescence and phosphorescence spectra of (a) 6AcBIQ and (b) 5AcBIQ
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Figure 4. Transient PL curves of 6AcBIQ and 5AcBIQ
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Figure 5. Transient PL curves of 6AcBIQ at different temperatures
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Figure 6. Current density-voltage-luminance plots of 6AcBIQ and 5AcBIQ at 5% doping concentration
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Figure 7. Quantum efficiency plots of 6AcBIQ and 5AcBIQ devices against luminance
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Figure 8. EL spectra of 6AcBIQ and 5AcBIQ devices
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Figure 9. Quantum efficiency-luminance plots of the 6AcBIQ devices with a mCPPFP host according
to doping concentration
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-
-
-
Benzoisoquinoline-1,3-dione as an acceptor of red thermally activated delayed
fluorescent emitters
Combination of benzoisoquinoline-1,3-dione and dimethylacridine in the donor-
acceptor type molecular design
High quantum efficiency of 11.2% in red thermally activated delayed fluorescent
devices