A Solution Processed Flexible Nanocomposite Electrode with Efficient Light
Extraction for Organic Light Emitting Diodes
Lu Li+, Jiajie Liang+, Shu-Yu Chou, Xiaodan Zhu, Xiaofan Niu, ZhibinYu, Qibing Pei1
Department of Materials Sciences and Engineering, California NanoSystems Institute, Henry
Samuli School of Engineering and Applied Science, University of California, Los Angeles,
California 90095
Correspondence and requests for materials should be addressed to Q.B.P (qpei@seas.ucla.edu).
1
Author to whom correspondence should be addressed, Email: qpei@seas.ucla.edu
[+] L.L. and J.L. contributed equally to this work
1
Scanning electron microscope (SEM) measurement (Figure S1)
(a)
(b)
Figure S1. (a) SEM image of backside of an SWNT/AgNW-nanocomposite film, and (b) SEM
cross-sectional image of an SWNT/AgNW-nanocomposite film.
2
Simulated and experimental enhancement factor changing with doping concentration
increasing (Figure S2)
Figure S2. Comparison of enhancement factor changing with doping concentration increasing
The device structure simulated was set up based on the definition of the software. The refractive
indices of glass, ITO, PEDOT:PSS, AgNW and Al were selected from the database of the
software. The refractive indices of BST nanoparticles and active layer materials were measured
by Gaertner L116B automatic ellipsometer. For the light source, incoherent isotropic dipole
sources were used and three separate simulations of the same dipole oriented along the x/y/z axes
were carried out and the results were summed up incoherently. The simulation region was 1 μm
by 10 μm and the PML (absorbing) boundaries were used on sides. The far field projection was
used to monitor the electric field intensity changing of the device. The far field distribution was
integrated to calculate the fraction of light that escapes into the air. The light extraction ratio was
obtained by calculating the ratio between the PLED based on ITO/glass and nanocomposite
substrate for the power transmitted into a 3 degree cone normal to the surface.
3
Current density versus voltage and luminance versus voltage characteristics of the white
polymer light-emitting device (Figure S3)
（a）
（b）
Figure S3. (a) The current density-bias voltage and (b) luminance-bias voltage characteristics of
the white polymer light-emitting diodes based on different types of substrates.
4
EL spectra of the green and white PLEDs based on ITO/glass and nanocomposite substrate
(Figure S4)
(a)
(b)
Figure S4. EL spectra of the green (a) and white (b) PLEDs based on ITO/glass and
nanocomposite substrate.
5
CIE coordinate changing of white PLED with different viewing angle and different
substrate (Figure S5)
Figure S5. CIE coordinates at different viewing angles of white PLEDs based on the
ITO/glass substrate and nanocomposite substrate. The x coordinate of the white PLED on
ITO/glass substrate changes from 0.336 at the normal angle to 0.439 at 90o. Both x and y
coordinates of the white PLED on nanocomposite substrate are fairly stable with the viewing
angle.
6
EL spectra of the green polymer light-emitting diode based on ITO/glass and
nanocomposite substrate (Figure S6)
（a）
（b）
）)）
Figure S6. EL spectra measured at different view angles of green PLEDs based on ITO/glass
(a) and nanocomposite (b) substrate. The ITO/glass device shows rather large angular
dependence. The intensity of the shoulder at 540 nm increases with viewing angle from. At 90º,
the emission color is almost white due to the waveguide mode in glass. For the device on
nanocomposite substrate, there is almost no change in the emission spectrum at all the viewing
angles tested.
7
Normalized luminance and photographs of green PLEDs (Figure S7)
(a)
(b)
(c)
(d)
Figure S7. (a) Angular distribution of the luminance of green PLEDs based on ITO/glass
substrate (black dot) and SWNT/AgNW-nanocomposite substrate (red square); Photographs
taken from the cathode side of PLEDs based on ITO/glass substrate (b, third finger from right is
lit) and SWNT/AgNW-nanocomposite substrate (c, two right fingers are lit); (d) Photograph of a
flexible green PLED driven at 5000 cd/m2.
8
Stress test under constant voltage driving of white polymer light-emitting diodes based on
ITO/glass and nanocomposite substrate (Figure S8)
Figure S8. The lifetimes of white PLEDs on ITO/glass and nanocomposite substrates were
tested by constant driving voltages in a nitrogen-filled glovebox without additional encapsulation.
The white PLEDs based on ITO/glass and nanocomposite substrates exhibit similar pattern of
degradation. For the device based on ITO/glass substrate, the luminance decreased by 50% of
from the initial brightness of 5000 cd/m2 in 200 min of continuous operation. For the device on
nanocomposite substrate, the luminance decreased by 45%.
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Luminance uniformity of a white PLED based on SWNT/AgNW-nanocomposite substrate
(Figure S9)
Figure S9. Luminance uniformity of a white PLED based on SWNT/AgNW-nanocomposite
substrate. The red circles represent the measurement spots of the Photoresearch PR-655.
Luminance of each is indicated in cd/m2. The variation of the emission intensities is less than
0.7% across the entire luminous area.
10
Transmittance of ITO/glass and composite substrates (Figure S10)
Figure S10. Transmittance (inclusive of substrate) and conductivity of ITO/glass, AgNWpolymer and SWNT/AgNW-polymer used in this work. In most of the visible wavelength range,
the transmittances of the polymer composite substrates are comparable to those of ITO/glass
substrate of the same sheet resistance.
11
Mechanical bending test in both compressive and tensile modes (Figure S11)
(a)
(b)
Figure S11. The results of compressive and tensile bending tests of SWNT/AgNWnanocomposite substrate are shown in Figure S11 (a). After 1000 cycles of bending, the sheet
resistance increased by 12% in compressive bending and 16% in tensile bending. Figure S11 (b)
shows the compressive and tensile strains of a SWNT/AgNW-nanocomposite substrate in
bending tests. The sheet resistance of the substrate shows a trend gradual degree with
compressive strain. The resistance change is very small. In the case of tensile deformation, the
resistance increases monotonically with strain, and increases by 92% at 20%. The resistance
change is reversible.
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