SUPPLEMENTAL MATERIAL
Internal structure of tunable ternary CdSe x S 1-x quantum dots unraveled
by X-ray absorption spectroscopy
Liang-Yih Chen (陳良益), a) Po-An Yang(楊普安), Chia-Hong Tseng(曾家
泓), and Bing-Joe Hwang(黃炳照) b)
Department of Chemical Engineering, National Taiwan University of Science
and Technology, 43, Section 4, Keelung Road, Taipei, 106, Taiwan.
Ching-Hsiang Chen(陳景翔)
Protrustech Corporation Limited, 3F.-1, No.293, Sec. 3, Dongmen Rd. East
District, Tainan, 701, Taiwan.
I. Transmission electron microscopy analysis:
Transmission electron microscopy (TEM) was used to investigate the structures
of CdSe x S 1-x QDs prepared by various compositional ratios of Se and S, as shown in
Figure S1. CdSe x S 1-x QDs synthesized with various compositions exhibited a
considerably uniform shape and particle size. The high-resolution TEM images and
their corresponding fast Fourier transfer (FFT) patterns are shown in the insets to
confirm the crystallinity of CdSe x S 1-x QDs as zinc-blende structure. These images
also revealed distinguished crystal planes that support the high crystallinity of
CdSe x S 1-x QDs.
FIG. S1 TEM images of 5 nm sized (a) CdSe 0.5 S 0.5 ; (b) CdSe 0.3 S 0.7 ; (c) CdSe 0.2 S 0.8
QDs. The insets are high-resolution atomic images and corresponding fast Fourier
transfer patterns. (scale bar: 20 nm)
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FIG S2. Diameter statistics of (a) CdSe 0.5 S 0.5 , (b) CdSe 0.35 S 0.7 , (c) CdSe 0.2 S 0.8 QDs
prepared with varied Se content of injection solution and (d) average sizes and size
distribution of CdSe x S 1-x QDs.
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FIG S3. The time variation of PL-QY of the synthesized CdSe 0.5 S 0.5 QDs, which
dispersed in toluene.
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II. Extended X-ray absorption fine structure (EXAFS) spectroscopy analysis:
CdSe x S 1-x
x
r
No
N
1.00
0.50
0.30
0.20
0.00
0.0017
0.0118
0.0199
0.0191
0.0001
R
Cd-S
Cd-Se
Cd-Cd
Se-Cd
3.50
2.48
(0.100) (0.009)
3.70
3.76
(0.090) (0.004)
3.50
2.53
(0.060) (0.004)
Se-S
Se-Se
3.60
3.57
(0.060) (0.005)
N
R
N
R
N
2.00
(0.070)
1.7
(0.13)
3.60
(0.160)
3.40
(0.310)
1.10
(0.110)
2.50
(0.120)
2.48
(0.0130)
2.53
(0.0110)
3.74
(0.008)
2.50
(0.007)
3.41
(0.009)
3.55
(0.011)
2.70
(0.080)
1.0
(0.110)
3.40
(0.210)
3.20
(0.190)
1.70
(0.170)
2.10
(0.150)
2.48
(0.009)
2.53
(0.014)
3.74
(0.008)
2.50
(0.012)
3.41
(0.008)
3.55
(0.013)
3.10
(0.040)
0.6
(0.110)
3.30
(0.150)
3.00
(0.220)
2.40
(0.110)
1.60
(0.090)
R
N
R
2.39
4.00
2.35
(0.022) (0.090) (0.005)
2.54
(0.009)
3.68
3.90
3.67
(0.011) (0.040) (0.006)
2.51
(0.011)
3.44
(0.008)
3.55
(0.012)
x: composition fraction of Se ; N: coordination number; R: bonding distance (Å); r: fitting residual
factor.
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