photoluminescence of mesoporous silica film impregnated with an erbium complex oun-ho park †, jae...
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Photoluminescence of Mesoporous Silica Film Impregnated with an Erbium ComplexOun-Ho Park†, Jae Young Bae, Ji-in Jung, and Byeong-Soo Bae
Laboratory of Optical Materials and Coating (LOMC), Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea
E-mail: oh-park@kaist.ac.kr http://www.sol-gel.net/lomc
Research direction
The 5th International Meeting of Pacific Rim Ceramic Societies
September 29 – October 2 2003, Nagoya Congress Center, Nagoya, Japan
Sample preparation of the mesoporous silica film impregnated with ErQ
Conclusions
References
FT-IR Spectra
Since planar optical amplifiers have a smaller interaction length with respect to erbium-
doped fiber amplifiers, higher erbium concentration is required to obtain a sufficient
optical gain.
high doping levels of erbium quench the fluorescence emission and reduce the
performance of the amplifier.
Theoretically, the most effective method for uniform dispersion is the periodic
arrangement of erbium ions in a matrix when high doping levels of Er3+ ions are required.
In this study, we impregnate Er complex into mesoporous silica film, and then measure
the photoluminescence for 1.5 m amplification.
Oun-Ho Park, Se-Young Seo, Ji-In Jung, Jae Young Bae, and Byeong-Soo Bae, J. Mater.
Res. 18[5], 1039 (2003)
Jae Young Bae, Ji-in Jung, Oun-Ho Park, Byeong-Soo Bae, Koodali T. Ranjit, L. Kevan, S
tudies in Surface Science and Catalyst 146, 65 (2003)
Jae Young Bae, Oun-Ho Park, Ji-in Jung, Koodali T. Ranjit, Byeong-Soo Bae, Micropor.
Mesopor. Mat., in press
Preparation of mesoporous silica films
- Precursor : Tetramethylorthosilicate
(TMOS)
- Solvent : Methanol (CH3OH)
- Surfactant : n-Cetyltrimethylammonium
Chloride [CH3(CH2)15N(CH3)3]Cl (CTACl)
Transparent mesoporous silica films are successfully fabricated using a sol-gel spin coating
method.
The obtained mesoporous silica films have hexagonal structure with 2 nm pore size.
Er complex is homogeneously impregnated into the mesoporous silica films by an immersing
technique, and its concentration can be easily controlled by changing the concentration of Er
complex solution.
Schematic Structure
PL intensity increases as the concentration of ErQ solution
increases due to the impregnation of ErQ into the pore.
Thermogravimetric Analysis
Abrupt weight losses take place at 280 & 310 oC due to the desorption
and the decomposition of CTACl, respectively.
Temperature profile is determined to calcine the residual
organic surfactants effectively.
XRD Result
Photoluminescence
Pore size : 2 nm Expected molecular size of ErQ : >1 nm It is expected that the impregnated ErQ
molecules are homogeneously distributed
due to the periodic pore arrangement.
FT-IR spectra of (a) as-synthesized and (b) calcined mesoporous
silica films Residual OH and organic templates are almost removed.
Synthesis of Mesoporous Silica Film
XRD patterns of (a) as-synthesized and (b)
calcined hexagonal mesoporous silica films
Characterization of Mesoporous Silica Film
Optical Properties of Mesoporous Silica Film Impregnated with ErQ
Temperature Profile for Calcination
N2 Adsorption Er distribution & Concentration Concentration Effect
Microstructure High Resolution TEM images
Obtained mesoporous silica films are optically
transparent in the range of visible wavelength. TEM cross-sectional images of perpendicular (a, b) and through (c) the pores of hexagonal
mesoporous silica thin films Pore size : ~ 2 nm
Transmittance
Erbium 8-hydroxyquinoline (ErQ) was incorporated
into the mesoporous silica films by impregnation. The
silica films were placed into 10 ml of 1.5 10-3–1.5
10-2 M erbium 8-hydroxyquinoline in ethanol. Ethanol
was removed by flowing nitrogen gas over the sample.
TMOS + HCl
Stirring for 1hr
Add methanol and
stirring for 1 hr
Add CTACl and stir for 24 hrs
Filtering and spin coating
Drying at 60, 130, & 200oC
Calcination at 550oC
for 12 hrs in air
NO
Er
N
ON
O
ErQ
Dissolve ErQ in EtOH
Immersion of mesoporous silica film
Ultrasonic treatment
Surface Cleaning
EtOH
Mesoporous silica film
0 100 200 300 400 500 600 70060
70
80
90
100
Der
iv. W
eig
ht
(%/o C
)
Temperature (oC)
Wei
gh
t (%
)
0.0
0.1
0.2
0.3
0.4
Water
Decomposition
of CTACl
Desorption of CTACl
0 4 8 12 16 20 24 280
100
200
300
400
500
600
700
Furnace cooled
Decomposition of CATCl
Desorption of CATCl
Tem
per
atu
re (
o C)
Time (hr)4000 3000 2000 1000
0.0
0.1
0.2
0.3
0.4Si-O-Si
Si-OCH3Organic templates
OH
(b)
(a)
Abs
orba
nce
(a.u
.)
Wavenumber (cm-1)
2 4 6 8 10
X 10
X 10
(a)
(b)
Inte
nsi
ty (
a.u
.)
2 / o
433 ± 2 nm
(a)
(b)
Average Roughness : 2 nm
50nm 20nm 20nm
(c)(b)(a)
Substrate
(a) SEM & (b) ARM Images
200 300 400 500 600 700 80040
50
60
70
80
90
100
Fused silica Coated film
Tra
nsm
itta
nce
(%
)
Wavelength (nm)
Silica wall
ErQ
Pore
Si wafer
ErQ impregnatedmesoporous silica film
1400 1450 1500 1550 1600 1650
0.0
0.2
0.4
0.6
0.8
1.0
Nor
mal
ized
PL
inte
nsit
y
Wavelength (nm)
1.5*10-2 N
0.7*10-2 N
1.5*10-3 N 0 N
0.0 0.2 0.4 0.6 0.8 1.0
100
200
300
400
500
600
700
800
adsorption desortion
ErQ Doped
ErQ undoped
Vol
ume
Ads
orbe
d cm
3 /g S
TP
Relative Pressure (P/P0)
Surface area (m2/g)
Pore size(nm)
ErQ undoped 920 2.1
ErQ doped 725 2.0
ErQ is impregnated into the pore!
500 1000 1500 20000
500
1000
1500
O
Si
Er
Yie
ld (
a.u.
)
Energy (keV)
Measured Silmulated
Depth profile and composition was
obtained by RBS measurements. Er is impregnated up to ~1021 ions/cm3.
0.0 0.4 0.8 1.2 1.6 2.0
0.0
0.2
0.4
0.6
0.8
1.0
Max
imum
PL
inte
nsit
y
Er atomic density ( 1021 ions/cm3)
PL is linearly proportional to erbium
atomic density., which implies No concentration quenching was
found up to ~1021 ions/cm3 of erbium
concentration.
ErQ impregnated mesoporous silica film shows a clear 1.5 m photoluminescence.
Impregnation of ErQ into the pore is confirmed by N2 adsorption.
Homogeneous distribution of ErQ in depth is confirmed by RBS measurement.
High concentration of erbium is impregnated without concentration quenching
PL is linearly proportional to the erbium concentration.
ErQ concentrationin ethanol solution
Er/Si ratio
Er atomic density (cm-
3)
1.5 10-3 N 0.012 1.8 1020
0.7 10-2 N 0.052 0.8 1021
1.5 10-.2 N 0.12 1.8 1021
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