Format for the IVL data:
Column 1 : data point number
Column 2 : voltage [ V ]
Column 3 : current [ A ]
Column 4 : luminance [ V ]
Format for the Spectrum data:
Column 1 : Wavelength [ nm ]
Column 2: Intensity [ arb. units ]
Your spectrum should look something like this:
Spectrum for ITO / TPD (500) / Alq3 (500) / Mg:Ag / Ag
30000
Intensity [ arb. units ]
25000
20000
15000
10000
5000
0
300
400
500
600
Wavelength [ nm ]
700
800
The photodiode detection set-up was like this:
OLED
8 mm
~ 37° cone captured
(~ 0.56 radians)
Detector (R = 5mm)
Output intensity profile from OLED: I(Θ) ~ cos2 Θ
So, fraction of light captured (α) is ~0.6
To get quantum efficiency (η) from luminance voltage (L) :
)[V ] *1e − 5[ A / V ] * R [W / A] * λ
d
max
α * I *1241
Where Rd is the responsivity
of the detector in W/A:
λ
Rd
405
6.0
530
3.0
630
2.5
Your I-L-V curves should
ultimately look something like
this:
I-V-L for ITO / TPD (500) / Alq3 (500) / Mg:Ag / Ag
1
1m
100µ
10µ
Quantum Efficiency [ % ]
background
Current [ A ]
(
L−L
η=
1µ
100n
10n
1n
100p
10p
1p
0.1
0
1
2
3
4
Voltage [ V ]
5
6
7
8
Your photovoltaic device I-V characteristics should look
something like this.
Tang, Appl Phys Lett. 48, 183 (1986).
Ag
3
PTCBI (500Å)
2
CuPc (300Å)
Current [mA/cm2]
ITO
1
VOC = 450mV
Glass
0
η = 0.95%
ff = 0.65
-1
ISC = 2.3mA/cm
2
-2
-3
-0.4
-0.2
0.0
Voltage [V]
0.2
0.4
What are the CIE coordinates of the OLED?
To answer this question use the X, Y, Z photopic
response curves in the Excel file “Calculation of CIE
coordinates.xls”. Multiply the OLED spectrum with
each of the X, Y, and Z curves, and add all the
values in each columns to obtain three numbers x, y,
z, respectively. The (x’,y’ ) CIE coordinates are then
given by x’ = x / (x+y+z), y’ = y / (x+y+z). Plot the
(x’,y’ ) coordinates on the CIE plot as below. Your
coordinates should match the color of the OLED.
CIE Plot
0.9
0.8
0.7
0.6
0.4
0.3
0.2
standard CRT
color triangle
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
x
0.1
0.0
y
0.5