Synthesis and characterization of solubility enhanced metal-free phthalocyanines for liquid crystal display black matrix of low dielectric constant

Article abstract of DOI:10.1016/j.dyepig.2011.08.001

For the liquid crystal display (LCD) black matrix (BM) with a low dielectric constant and high light absorption property, it is advantageous to employ dyes instead of carbon black or pigments. For this purpose, the dyes should have high solubility in indu

Full text of DOI:10.1016/j.dyepig.2011.08.001

Dyes and Pigments 92 (2012) 942e948
Contents lists available at ScienceDirect
Dyes and Pigments
journal homepage: www.elsevier.com/locate/dyepig
Synthesis and characterization of solubility enhanced metal-free phthalocyanines
for liquid crystal display black matrix of low dielectric constant
Woosung Lee a, Sim Bum Yuk a, Jun Choi a, Dong Hyun Jung b, Seung-Hoon Choi b,
,
Jongseung Park c, Jae Pil Kim a
*
a Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, Republic of Korea
b Insilicotech Co. Ltd., A-1101, Kolontripolis, 210, Geumgok-Dong, Bundang-Gu, Seongnam-Shi, Gyonggi-Do 463-943, Republic of Korea
c Department of Textile Industry, Dong-A University, Busan 604-714, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
For the liquid crystal display (LCD) black matrix (BM) with a low dielectric constant and high light
absorption property, it is advantageous to employ dyes instead of carbon black or pigments. For this
purpose, the dyes should have high solubility in industrial organic solvents. For improved solubility in
industrial solvents, three metal-free phthalocyanines (PC), peripherally substituted with bulky groups,
were synthesized and dye-based BMs were fabricated. The solubility as well as the spectral and thermal
properties of the dyes were examined, and the optical, thermal and dielectric properties of a dye-based
black matrix were tested. The greenish phthalocyanine dyes with high molar extinction coefficients and
high thermal stability showed enhanced solubility in industrial solvents as a result of the greater steric
hindrance among the dye molecules and higher affinity between the dye molecules and solvents. The
dye-based BMs had low dielectric constants and exhibited superior optical properties and satisfactory
thermal stability.
Received 22 July 2011
Received in revised form
3 August 2011
Accepted 3 August 2011
Available online 16 August 2011
Keywords:
Black matrix
Dyes
Phthalocyanine
Dielectric constant
Light absorption
Solubility
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
overcome. On the other hand, dyes generally have low thermal
stability compared to carbon black and organic pigments. Therefore,
The black matrix (BM), a component of LCD color filters, divides
the red, green and blue (RGB) pixels of the color filter and blocks
light leaking from the areas between the RGB color patterns
enhancing contrast ratio of color filters [1]. According to the
component materials, BM can be divided into metal oxide, carbon
black, titanium black and organic pigment types [2]. Among the
various types of BMs, a carbon black BM manufactured by spin-
coating is generally employed in industry. The advantage of using
carbon black as a BM component arises from its high light
absorption property, high thermal stability and low cost [2,3]. On
the other hand, malfunctions of the thin film transistor (TFT) of
a LCD can occur due to the high dielectric constant of carbon black.
To avoid this problem, an organic pigment BM with a low dielectric
constant can be used despite its low spectral property due to the
lower molar extinction coefficient of organic pigments [4].
the dyes for BM need to be structurally stable [5,6]. They also should
have good solubility in industrial solvents, such as propylene glycol
methyl ether acetate (PGMEA) and cyclohexanone [6].
In this study, green phthalocyanine (PC) dyes with high thermal
stability and high solubility were designed. Three metal-free PC
dyes were synthesized by introducing substituents including alkyl
or alkoxy groups to the peripheral position of the PC rings, and their
spectral properties, solubilities and thermal stabilities were
measured. Dye-based BMs were fabricated and their optical and
dielectric properties were examined.
2. Experimental
2.1. General
If dyes are used for the manufacture of the BM, the high dielectric
constant and low light absorption of conventional BMs can be
2,5-bis-(1,1-dimethylbutyl)-methoxyphenol,
4-hydroxy-3-tert-
butylanisole, 2,4-bis(1,1-dimethylpropyl)phenol were purchased from
TCI and, dimethyl sulfoxide (DMSO), potassium carbonate anhydrous,
dichloromethane, m-xylene anhydrous, ethanol anhydrous and
lithium granule purchased from Sigma Aldrich were used as received.
* Corresponding author. Tel.: þ82 2 880 7187; fax: þ82 2 880 7238.
E-mail address: jaepil@snu.ac.kr (J. P. Kim).
0143-7208/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.dyepig.2011.08.001

W. Lee et al. / Dyes and Pigments 92 (2012) 942e948
943
All reagents and solvents were of reagent-grade quality and obtained
from commercial suppliers. Transparent glass substrates were
provided by Paul Marienfeld GmbH & Co. KG and acrylic binder
LC20160 were supplied by SAMSUNG Cheil industries Inc.
nitrogen at a heating rate of 10 ꢀC minꢁ1 using a TA Instruments
Thermogravimetric Analyzer 2050. Dielectric constants were
measured using Edward E306 thermal evaporator and HP 4294A
precision impedance analyzer.
1H NMR spectra were recorded on a Bruker Avance 500 spec-
trometer at 500 MHz using chloroform-d and tetramethylsilane
(TMS), as the solvent and internal standard, respectively. Matrix
Assisted Laser Desorption/Ionization Time Of Flight (MALDI-TOF)
mass spectra were collected on a Voyager-DE STR Biospectrometry
2.2. Synthesis
2.2.1. Preparation of 4-(2,5-bis(1,1-dimethylbutyl)-4-
methoxyphenoxy)phthalonitrile (1a)
Workstation with a-cyano-4-hydroxy-cynamic acid (CHCA) as the
4-Nitrophthalonitrile (1 g, 5.77 mmol) and 2,5-bis-(1,1-
dimethylbutyl)-methoxyphenol (1.68 g, 5.77 mmol) were dis-
solved in dry DMSO (30 ml) and anhydrous K2CO3 (1.06 g,
7.66 mmol) was added in portions during 4 h. The mixture was
stirred at 40 ꢀC for 24 h under nitrogen atmosphere. After filtering
the reaction mixture, the residue was extracted with CH2Cl2 and
matrix. Fourier transform infrared (FT-IR) spectra were recorded in
the form of solid on a Thermo Scientific Nicolet 6700 FT-IR spec-
trometer. Elemental analysis was done on CE Instrument EA1112.
Absorption spectra were measured using a HP 8452A spectropho-
tometer. Thermogravimetric analysis (TGA) was conducted under
Scheme 1. Synthesis of the prepared dyes.

944
W. Lee et al. / Dyes and Pigments 92 (2012) 942e948
Table 1
dried by rotary evaporation. Pure product (2.19 g, 5.23 mmol) was
collected by column chromatography on silica gel using EA/hexane
(10:1) mixture as an eluent.
Solubility of the dyes at 20 ꢀC.
Dye
PGMEA
Cyclohexanone
Yield 91%; 1H NMR (CDCl3, ppm): 7.69 (d, 1H), 7.22 (s, 1H), 7.14
(d, 1H), 6.82 (s, 1H), 6.63(s, 1H), 3.08 (s, 3H, eOeCH3), 1.71 (m, 2H),
1.56 (m, 2H), 1.26(d, 12H), 1.04 (m, 2H), 0.96 (m, 2H), 0.81 (t, 3H),
0.71 (t, 3H).
1b
2b
3b
PB 16
4 wt%
2.2 wt%
Less than 1.0%
Insoluble
10 wt%
2.8 wt%
Less than 1.0%
Insoluble
2.2.2. Preparation of 4-(3-tert-butyl-4-methoxyphenoxy)
phthalonitrile (2a)
coated black matrix was then dried at 80 ꢀC for 20 min, prebaked
at 150 ꢀC for 10 min, and postbaked at 230 ꢀC for 1 h. After each
step, the coordinate values of the black matrix were measured.
2a was synthesized following the same procedure for 1a using 2
(1 g, 5.54 mmol), 4-nitrophthalonitrile (0.96 g, 5.54 mmol), DMSO
(30 ml), and anhydrous K2CO3 (1.06 g, 7.66 mmol).
Yield 85%; 1H NMR (CDCl3, ppm): 7.71 (d, 1H), 7.26 (s, 1H), 7.22
(d,1H), 7.01 (s, 1H), 6.77 (m, 2H), 3.83 (s, 3H, eOeCH3), 1.30 (m, 9H).
2.4. Measurement of spectral and chromatic properties
The absorption spectra of the synthesized dyes and the trans-
mittance spectra of the dye-based BM were measured using
a UVevis spectrophotometer. The chromatic values were recorded
on a color spectrophotometer (Scinco colormate).
2.2.3. Preparation of 4-(2,4-bis(1,1-dimethylpropyl)phenoxy)
phthalonitrile (3a)
3a was synthesized following the same procedure for 1a using 3
(1.2 g, 5.12 mmol), 4-nitrophthalonitrile (0.89 g, 5.12 mmol), DMSO
(30 ml), and anhydrous K2CO3 (1.06 g, 7.66 mmol).
Yield 82%; 1H NMR (CDCl3, ppm): 7.71 (d, 1H), 7.35 (s, 1H), 7.27
(s, 1H), 7.22 (d, 1H), 7.18 (d, 1H), 6.75 (d, 1H), 1.66 (m, 4H), 1.30 (d,
12H), 0.70 (t, 3H), 0.63 (t, 3H).
2.5. Measurement of solubility
Small amounts of the dyes (0.05 g) were added to the solvents
(0.5 g). The solutions were stirred for 20 min and left to stand for
24 h at room temperature. Precipitations were visually checked and
additional solvents (0.25 g) were added into the solutions until it
made clear solutions. The solubility of the dye was recorded as
weight percentage of dyes in the clear solutions.
2.2.4. Preparation of tetrakis(2,5-bis(1,1-dimethylbutyl)-4-
methoxyphenoxy)-phthalocyanine (1b)
1a (0.9 g, 2.38 mmol) was dissolved in anhydrous xylene (50 ml)
and ethanol (10 ml) under nitrogen atmosphere and Li (0.13 g,
18.7 mmol) was added in the solution. The reaction mixture was
stirred at 150 ꢀC for 5 h. After cooling the solution, the resulting
slurry was extracted with CH2Cl2 (100 ml) and washed with satu-
rated NaCl solution. The pure product (0.53 g, 0.31 mmol) was
obtained by column chromatography on silica gel using CH2Cl2 as
an eluent.
2.6. Measurement of thermal stability
The thermal stability of the synthesized dyes was evaluated by
thermogravimetry (TGA). The prepared dyes were heated to 110 ꢀC
and held at that temperature for 10 min to remove the residual
water and solvents. The dye was then heated to 230 ꢀC and held at
that temperature for 60 min to simulate the processing thermal
conditions of color filter manufacturing. The dyes were finally
heated to 500 ꢀC to determine their degradationꢁt1emperature. The
heating was carried out at the rate of 10 ꢀC min under nitrogen
atmosphere. To check the thermal stability of the dyes in black
matrix, the fabricated black matrix was heated to 230 ꢀC for 1 h in
a forced convection oven (OF-02GW Jeiotech Co., Ltd.). The color
Yield 54%; MALDI-TOF MS: m/z 1675.9 (100%, [M þ 2K]þ). FT-IR
(KBr, cmꢁ1): 3289 (N-H). Calcd for C108H138N8O8: C, 77.38; H, 8.30;
N, 6.68; O, 7.64%. Found: C, 77.36; H, 8.27; N, 6.66; O, 7.69%.
2.2.5. Preparation of tetrakis(3-tert-butyl-4-methoxyphenoxy)-
phthalocyanine (2b)
2b was synthesized following the same procedure for 1b using
2a (1 g, 3.26 mmol), Li, ethanol (10 ml), and anhydrous xylene
(50 ml).
Yield 41%; MALDI-TOF MS: m/z 1227.1 (100%, [M þ 2K]þ). FT-IR
(KBr, cmꢁ1): 3289 (N-H). Calcd for C76H74N8O8: C, 74.37; H, 6.08;
N, 9.13; O, 10.43%. Found: C, 74.37; H, 6.08; N, 9.12; O, 10.45%.
difference values (DEab) before and after heating were measured on
a color spectrophotometer (Scinco colormate) in CIE L’a’b’ mode.
2.7. Geometry optimization of the synthesized dyes
2.2.6. Preparation of tetrakis(2,4-bis(1,1-dimethylpropyl)phenoxy)-
phthalocyanine(3b)
3b was synthesized following the same procedure for 1b using
3a (1.1 g, 3.05 mmol), Li, ethanol (10 ml), and anhydrous xylene
(50 ml).
The geometry and electric structure of the studied dyes are
optimized by the hybrid density functional theory (DFT) method at
the PBE/DNP theory level performed on Materials Studio 5.0 DMol3
program package.
Yield 41%; MALDI-TOF MS: m/z 1443.7 (100%, [M þ 2K]þ). FT-IR
(KBr, cmꢁ1): 3293 (N-H). Calcd for C96H114N8O4: C, 79.85; H, 7.96; N,
7.76; O, 4.43%. Found: C, 79.88; H, 8.75; N, 6.33; O, 4.25%.
N
N
N
H
H
N
2.3. Preparation of dye-based black matrix
N
N
N
N
The ink for a black matrix was composed of the dye (0.01 g),
cyclohexanone (4.0 g), and LC20160 (14 g) as a binder based on
acrylate. The prepared dye-based inks were coated on a transparent
glass substrate using a MIDAS System SPIN-1200D spin coater. The
coating speed was initially 100 rpm for 5 s, which was then
increased to 200 rpm and kept constant for 20 s. The wet dye-
PB 16
Fig. 1. Structure of Pigment Blue 16.

W. Lee et al. / Dyes and Pigments 92 (2012) 942e948
945
3. Results and discussion
between nitro phthalonitriles and phenols including functional
groups (1,2,3) [7]. Each reaction was conducted under similar
conditions and all products were obtained in high yield over 80%.
The structures of the synthesized precursors were confirmed by 1H
NMR.
3.1. Synthesis of dyes
Three metal-free PCs with enhanced solubility were designed
and synthesized, as shown in Scheme 1. Precursors (1a,2a,3a) were
synthesized through a nucleophilic aromatic substitution reaction
The metal-free PCs (1b,2b,3b) were synthesized by a cyclo-
tetramerization reaction of the precursors and purified by column
Fig. 2. Geometry-optimized structures of the prepared dyes.

946
W. Lee et al. / Dyes and Pigments 92 (2012) 942e948
Table 3
1b
Electronic energies of the prepared dyes.
2b
1b
2b
3b
3b
PB 16
1.5
1.0
0.5
0.0
HOMO þ 3
HOMO þ 2
HOMO þ 1
HOMO
ꢁ5.061
ꢁ4.972
ꢁ4.958
ꢁ4.432
1.316
ꢁ5.086
ꢁ5.002
ꢁ4.934
ꢁ4.445
1.318
ꢁ3.127
ꢁ3.093
ꢁ1.733
ꢁ1.531
ꢁ5.506
ꢁ5.258
ꢁ5.233
ꢁ4.501
1.326
ꢁ3.175
ꢁ3.133
ꢁ1.783
ꢁ1.573
ΔE
LUMO
ꢁ3.116
ꢁ3.076
ꢁ1.722
ꢁ1.515
LUMO ꢁ 1
LUMO ꢁ 2
LUMO ꢁ 3
ΔE means the energy gap difference between HOMO and LUMO.
anti-aggregation effects between the PC molecules as well as the
affinity between the ether linkages of the dyes and solvent mole-
cules [6]. The solubility of dye 2b was relatively lower than that of
dye 1b because of its less bulky alkyl substituents. Dye 3b was
barely soluble in industrial solvents due to little affinity between
the dyes and solvent molecules.
400
500
600
700
800
Wavelength(nm)
Fig. 3. Absorption spectra of the synthesized dyes in CH2Cl2 (10ꢁ5 mol lꢁ1) and PB 16
in sulfuric acid (10ꢁ5 mol).
The solubility of the dyes corresponded to the simulation data
optimized by the Materials Studio 5.0 DMol3 program. Fig. 2 shows
the optimized structures of the dyes with bulky substituents out of
the planar core. The bulky substituents of dyes 1b and 2b were
twisted perpendicular to upward and downward directions of the
molecular plane, whereas those of dye 3b were twisted toward one
side of the molecular plane. Therefore, dyes 1b and 2b were more
soluble in industrial solvents than dye 3b.
chromatography [8]. Theoretically, metal-free PCs synthesized by
monosubstituted phthalonitriles can have 4 constitutional isomers:
C4h,C2v,Cs,D2h. Assuming a statistical distribution, the 4 isomers are
expected to be mixed in the ratio of 1:2:4:1 [9]. No attempts to
separate these isomers were made and all metal-free PCs were
obtained in relatively high yield. The structures of synthesized PCs
were confirmed by MALDI-TOF spectroscopy, FT-IR spectroscopy,
and elemental analysis.
3.3. UVevis absorption spectra
3.2. Solubility
Fig. 3 and Table 2 show the absorption spectra of dye 1be3b in
CH2Cl2 and PB 16 in sulfuric acid, respectively. To apply a dye to
a BM, it should have strong and broad absorptions in the visible
region. The greenish dyes exhibited absorption maxima in the
706e708 nm range, displaying typical Q-band absorptions in the
600e750 nm range as well as B-band absorptions in the
300e450 nm range [11]. The characteristic Q and B bands were due
The dyes need to be dissolved in industrial solvents, such as
PGMEA and cyclohexanone, to a concentration of at least 4e5 wt%
to be applied for BM [6]. Generally, non-substituted PCs tend to
form various crystal structures due to molecular interactions
caused by their planar structures. Therefore, non-substituted PCs
have low solubility in most organic solvents, which has limited
their applications [9].
Substituents including bulky alkyl groups or alkoxy groups were
introduced at their peripheral positions to enhance the solubility of
PCs. As a result, the solubility of metal-free PCs increased signifi-
cantly compared to that of non-substituted metal-free PC (PB 16).
This is due to the steric hindrance between the planes of the PC
molecules caused by the bulky aromatic substituents rotated out of
the plane of the molecule. In addition, as previously mentioned, the
synthesized dyes would exist in a mixture of 4 isomers, which
would increase their solubility due to the unsymmetrical isomers Cs
and C2v among them [10]. Table 1 lists the solubility of the PC dyes
and PB 16, and Fig. 1 shows the structure of PB 16.
to
pep* transitions in the heteroaromatic 18-p electron system
[12]. The dyes showed similar spectral properties, indicating that
the conjugations of the dyes were not much affected by the change
in introduced substituents [11]. The molar extinction coefficients of
the dyes were approximately 140,000e150,000, which significantly
exceeded those of the pigments. Therefore, the amounts of the dyes
needed for BM can be reduced.
100
80
60
40
20
0
Dyes 1b and 2b, which included alkyl and alkoxy groups at their
terminal positions, showed higher solubility than dye 3b, which
contained only alkyl groups as substituents. In particular, the
solubility of dye 1b in cyclohexanone reached 10 wt% due to the
Table 2
Absorption maxima and extinction coefficients of the prepared dyes in CH2Cl2 and
PB 16 in sulfuric acid.
Dye
lmax
3
max
(nm)
(L molꢁ1 cmꢁ1
)
1b
2b
3b
PB 16
708
706
706
774
140,875
142,473
152,855
10,756
400
500
600
700
Wavelength
Fig. 4. Transmittance spectra of the spin-coated black matrix with dye 1b.

W. Lee et al. / Dyes and Pigments 92 (2012) 942e948
947
Table 5
100
90
80
70
60
50
40
30
20
10
0
Dielectric constants and constitutions of the dye-based black matrix.
Frequency (kHz)
Dielectric constant( 3 r, average)
1b-00
1b-20
1b-40
1b-60
1b-80
1b-100
0.1
1
10
100
200
500
700
1000
26.39
25.47
20.65
18.72
18.22
17.57
17.34
17.11
1.2013
20.07
19.44
16.10
14.78
14.41
13.94
13.77
13.61
13.94
13.56
11.60
10.89
12.61
10.44
10.35
10.25
6.90
6.78
6.16
5.95
5.87
5.78
5.74
5.70
6.92
6.81
6.25
6.04
5.96
5.86
5.83
5.79
4.96
4.84
4.23
4.12
4.08
4.02
3.99
3.99
1b
2b
3b
Thickness
Electrode radius
mm
280, 285, 280 mm
1b-00
(wt%)
1b-20
(wt%)
1b-40
(wt%)
1b-60
(wt%)
1b-80
(wt%)
1b-100
(wt%)
0
100
200
300
400
Binder
Carbon black
Dye 1b
50
50
50
40
10
50
30
20
50
20
30
50
10
40
50
Temperature
50
Fig. 5. Thermogravimetric analysis (TGA) of the prepared dyes.
3.5. Dielectric properties
These results corresponded to the simulation data optimized by
the Materials Studio 5.0 DMol3 program. As shown in Table 3, the
orbital lobes and HOMO-LUMO energy gaps of the dyes were
almost identical. Accordingly, the changes in substituents did not
affect the absorption maxima of the dyes. Fig. 4 shows the trans-
mittance spectra of the dye-based BM fabricated with the dye 1b.
The fabricated BM absorbed light broadly in the 400e450 nm and
600e700 nm ranges. Therefore, compensatory dyes absorbing light
in the 450e600 nm range will be needed for complete absorption
of light in the visible range.
The dielectric constant of BM needs to be <7 for satisfactory
industrial applications with a current thickness of BM (1e1.5 m). On
m
the other hand, carbon black BM has a high dielectric constant >20,
which can cause malfunctions of LCD TFTs due to interference of the
TFT electric signal with carbon black [4]. Therefore, to reduce the
dielectric constant of BM, dye-based BM and carbon black-dye hybrid
type BMs were fabricated and their dielectric properties were tested.
Table 5 lists the dielectric constants and constitutions of the
prepared BMs. The 6 hybrid type BMs were fabricated with varied
compositions of dye 1b and carbon black. The BM 1b-00 prepared
with carbon black only had the highest dielectric constant. The
dielectric constant of BM decreased significantly with decreasing
carbon black and increasing dye concentration due to the low
dielectric character of the dye. In particular, BM 1b-100 prepared
with the dye only had the lowest dielectric constant of 3.99 at
a frequency of 1000 kHz. In addition, the dielectric constants of the
samples were a function of the applied electric field frequency. The
dielectric constant of BM decreased gradually with increasing
frequency from 0.1 kHz to 1000 kHz. This was attributed to the lag
in charge transfer inside the dye molecule caused by the rapid
change in the external electronic field [17]. Among the 6 BMs
prepared, those containing more than 30 wt% of dye had a dielec-
tric constant <7 at the working frequency range (100e300 Hz).
3.4. Thermal properties
Phthalocyanines are highly stable dyes due to the strong
pep
stacking interactions from their planar structures [13]. In addition,
their high molecular weight is favorable for intermolecular inter-
actions, such as Van der waals forces. On the other hand, phtha-
locyanines including substituents show reduced stability due to
anti-aggregation effects.
For the current LCD manufacturing process, dye molecules need to
be stable up to 230 ꢀC [6]. As shown in Fig. 5, dyes 1b and 2b showed
<1% weight loss after 1 h at 230 ꢀC, whereas dye 3b showed
approximately 10% weight loss and degraded gradually with
increasing temperature. This was attributed to the initial decompo-
sition of phthalocyanines from the terminal groups at 230e250 ꢀC. As
PC dyes containing alkoxy groups as substituents were reported to be
more stable than those containing terminal alkyl groups, dye 1b and
2b showed higher stability than dye 3b [14].
4. Conclusion
Three solubility enhanced phthalocyanine dyes were synthe-
sized, and the dye-based BMs were fabricated with the most
soluble dye. The increase in solubility of the prepared dyes was
attributed to bulky functional substituents at the peripheral posi-
tions of them. Since all dyes had high molar extinction coefficients,
dye-based BMs absorbed light in the visible region with the small
amounts of the dyes. In addition, the dyes including terminal
alkoxy groups showed suitable thermal stability for commercial use
due to terminal alkoxy groups are stable at postbaking tempera-
ture. The dielectric constants of the BMs containing more than
30 wt% of dyes were significantly lower than that of the BM
prepared with carbon black only.
To measure the thermal stability of BM film, dye 1b was spin
coated on a glass and the
DEab value of the film was measured. As
shown in Table 4, the Eab value of the film was 3.434 after heating
D
for 90 min at 230 ꢀC. This suggests that the original color of the BM
was well maintained due to little degradation of the dye [15]. The
thermal stability of dye-based BMs would be improved further if
a commercial binder, adjusted for the pigments, can be optimized
to the dye [16].
Table 4
The coordinate values corresponding to the CIE 1931 chromaticity diagram of the
dye-based black matrix.
Acknowledgments
Black matrix
1b Prebake
Postbake
L
a
b
D
Eab
This study was supported by a grant from the Strategy project
funded by the Ministry of Knowledge Economy (MKE), Republic of
Korea.
74.6417
77.3913
ꢁ65.6547
ꢁ66.2442
6.851
8.824
3.434

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W. Lee et al. / Dyes and Pigments 92 (2012) 942e948
ˇ
[9] Erdogmus¸ A, Nyokong T. Novel, soluble, fluxoro functional substituted zinc
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