Supplementary Material
Deep blue energy harvest photovoltaic switching by heptazole-based organic Schottky
diode circuits
Running Title: Organic heptazole photovoltaic switching circuits
Junyeong Lee1†, Syed Raza Ali Raza1,2†, Pyo Jin Jeon1, Jin Sung Kim1, and Seongil Im1*
1
Institute of Physics and Applied Physics, Yonsei University 50 Yonsei-ro, Seodaemun-gu,
Seoul, 120-749, Korea
E-mail: [email protected]
2
Department of Physics, University of Azad Jammu & Kashmir, Muzaffarabad, Azad
Kashmir, Pakistan
†
These authors contributed equally to this work.
Keywords: Photovoltaic, Optical switching, Heptazole, organic Schottky diode, diode circuit,
open-circuit voltage
*
Corresponding Author
Prof. Seongil Im
Email: [email protected]
Address: Science Building #240, Institute of Physics and Applied Physics, Yonsei University
50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749, Korea
Telephone: 82-2-2123-2428
Table S1. State-of-the-art PV devices for dynamic photo-detecting to be compared.
1
Materials
Device
Signal Type Dark On/Off ratio
Output
Photosensitivity
1
Heptazole film
Schottky
Voltage
Ion/Ioff ~ 10
0.3 V ~ 1.2 V
Iphoto/Idark ~ 103
2
ZnO nanowire
p-n Diode
Voltage
unknown/Ion ~ 10 μA
~ 0.2 V
unknown/Iphoto ~ 1 A
3
Graphene/Si
Schottky
Voltage
unknown/Ion ~ 40 μA/cm2
< 0.2 V
4
(Pd-doped)MoS2/n-Si
p-n Diode
Voltage
unknown/Ion ~ 4 mA/cm2
< 0.5 V
5
CNT/p-Si
p-n Diode
Current
unknown/Ion ~ 20 μA
> 10 μA
Iphoto/Idark ~ 104
6
p-CuO/n-Si Nanowire
p-n Diode
Current
Ion/Ioff ~ 105
~ 5 μA
unknown/Iphoto ~ 4 μA
7
n-ZnO nanowire/p-GaN
p-n Diode
Voltage
unknown/Ion ~ 1 μA
<3V
unknown/Iphoto ~ 2 μA
Used photon/selectivity
Response Time
5
unknown/Iphoto ~ 20
μA/cm2
unknown/Iphoto ~ 10
μA/cm2
Applications
Year/Ref.
photo-detector/inverter, optical logic, photovoltage-driven gate
switching
Our work
1
450 nm – 360 nm/Good
~50 ms
2
30 W Xe Lamp/Bad
~30 ms
photo-detector
2012/[1]
3
500 nm/Bad
~ several ms
photo-detector
2015/[2]
4
1100 nm - 300 nm/Bad
~ 200 us
photo-detector
2016/[3]
5
650 nm/Bad
~ 20 ms
photo-detector, optical logic, optical converter
2014/[4]
6
1064 nm - 405 nm/Bad
~ 60 us
photo-detector
2014/[5]
7
325 nm/Good
~ 200 us
photo-detector, optical logic
2011/[6]
In the Table S1 for detailed comparison, most of the state-of-the art devices are taking
inorganic materials with nano-dimensions, which can be limited in convenience for device
fabrication and applications.
2
Au
semicon.
Au
CYTOP/SiO2
p++ silicon
Absorbance
(a.u.)
hυ
Areal DOS
(eV-1cm-2 x 1012)
(a)
(b) Heptazole
(d)
(f)
DNTT
Pentacene
S
S
10
10
(c)
10 (g)
8
(e)
8
8
6
6
6
4
4
4
2
2
2
0
1.5
0
1.5
2.0
2.5
3.0
Energy (eV)
2.0
2.5
3.0
Energy (eV)
0
1.5
2.0
2.5
3.0
Energy (eV)
Figure S1. Exciton binding energy properties of heptazole, DNTT, and pentacene thin films
are compared through photo-excited charge collection spectroscopy (PECCS) and UV/Vis
spectroscopy. (a) Schematic diagram of PECCS measurement where the organic FETs are
exposed to monochromatic lights. The optical absorbance spectrums and areal DOS plots of
(b,c) heptazole, (d,e) DNTT, and (f,g) pentacene are shown respectively. The difference
between the optical and photoelectric gaps is thought to be the exciton binding energy.
Table S2. HOMO-LUMO gaps of heptazole, DNTT, and pentacene thin films through
UV/Vis absorption (optical gap) and PECCS (photoelectric gap) are summarized.
Materials
HOMO-LUMO gap
by UV/Vis absorption
(eV)
(Optical gap)
HOMO-LUMO
gap
by PECCS (eV)
(Photoelectric
gap)
Exciton Binding
Energy (meV)
Reference
Heptazole
2.96
3.00
~40
31
DNTT
2.77
2.87
~100
This work
Pentacene
1.85
1.97
~120
30, 35
3
Figure S2. (a) Photocurrent and (b) responsivity of our Schottky diode with 50 nm-thin
heptazole. (c) Photocurrent and (d) responsivity from 150 nm-thick heptazole device.
4
(a)
(b)
Current Density (mA/cm2)
15
0
10
-2
5
Va
-4
0
Light
-6
Va
-5
Dark
Blue
-8
-10
L1 Off & L2 Off
L1 On & L2 Off
L1 Off & L2 On
L1 On & L2 On
0.0
0.2
Voltage (V)
0.4
-10
-15
0.6 -0.6 -0.4 -0.2 0.0
Light 2 Light 1
0.2
0.4
0.6
Voltage (V)
Figure S3. Current-Voltage curve under dark and blue illumination for (a) single diode and
(b) double diode circuits are shown in linear scale to provide more precise VOC information.
5
(a)
0.2
3
296K
300K
305K
310K
315K
320K
I/T2 (pA/K2)
Current (μA)
0.3
(b)
2.7
I = AA*T2e-qΦ/kT(eqV/ηkT-1)
2.4
0.1
ln(I/T2) = ln(AA*) – q(Φ-V/η)/kT
qΦ = 0.92 eV, [V = 2 V, η = 2.3]
1.5
1.6
1.7
1.8
1.9
2.0
3.1
Voltage (V)
3.2
1000/T
3.3
3.4
(K-1)
Figure S4. Schottky junction barrier height (=0.92 eV) obtained from (e) temperaturedependent I-V measurement and (f) Richardson’s plot [7]
6
-6
(b)
(c)
(a)
Glass
Va
10
|Current (A)|
ITO
-8
GND
Pentacene
Green
Va
Va
Va
Al
(d)
Red
10
-10
10
-12
10
Dark
Red
Green
-14
10
-2
-1
0
1
Voltage (V)
2
L1 Off & L2 Off
L1 Off & L2 On
L1 On & L2 Off
L1 On & L2 On
L1 Off & L2 Off
L1 Off & L2 On
L1 On & L2 Off
L1 On & L2 On
-2
-1
0
1
Voltage (V)
2
-2
-1
0
1
2
Voltage (V)
Figure S5. (a) Cross section schematic of our pentacene-based Schottky diode with (b) I-V
behavior under red and green illuminations. I-V behavior of double diode circuit under (c)
red and (d) green illuminations
7
Light 1
Light 2
On Off
0.4
0.4
(a)
0.2
0.2
0.0
0.0
-0.2
-0.4
0
0.4
20
40
60
80
100
(b)
0
0.0
-0.2
-0.2
120
180
240
300
20
40
60
80
100
0.4
0.0
-0.4
(c)
-0.4
0.2
60
On Off
-0.2
0.2
0
Off On
Light 2
Voltage (V)
Voltage (V)
Light 1
Off On
-0.4
Pentacene
Heptazole
(d)
0
Time (s)
5
10
15
20
Time (s)
Figure S6. Time domain VOUT plot for pentacene double Schottky diodes circuit under
alternate L1/L2 red illuminations with period of (a) 20 s and (b) 60 s. Optical switching
operation under blue illumination is also recorded in (c) and (d), where the dynamic behavior
of pentacene- and heptazole-based diode circuits is compared. (The same VOC can be
obtained from the two circuits but switching speed of heptazole diode PV circuit was faster.)
Supplementary Video 1 caption. Dynamic photo switching and inverting of our organic
Schottky diode circuits as demonstrated under deep blue LEDs.
8
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