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Inorganic Nanoparticles:
From colloids to photovoltaic devices
E Arici1* , J.
E.
J N.
N Feritas2, N.
N S.
S Sarıciftci1, A.F.
A F Nogueiria2
1Linz
Institute for Organic Solar Cells
JKU, Linz
2Chemıstry Depatment Unıversıty of Campına Brazil
Overview
• Synthesis principles of inorganic QDs
• Organic-inorganic hybrid solar cells
– CdSe QDs as electron acceptor
– CuInS2 QDs as electron donor
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What are Quantum Dots (QDs)?
Photostability
Compatibility with diverse matrices
Broad Absorbance Range
g
High : 106 M/cm3
OPVs
Tunable Colors via QD size
Single Excitation Source
EQE: 12-60%
QLEDs
Diagnostic Marker
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Quantum Confinement
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Absorption
p
of CdSe QDs
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Increasing size of the QDs leads to lower band gap & higher extinction coefficient
Synthesis:Hot Injection
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Role of the surfactant
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(TOPO)
(HPA)
Shape control
Anisotropic growth of CdSe QDs
Faster growth
in c axis!
Main reason:
CdSe in wurtzide structure
- Different number of
dangling bonds at 001 face
only TOPO
TOPO/HPA:
85/15
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Synthetic controll of the
anisotropic growth
- High monomer concentration
- Face selective surfactants
TOPO/HPA:
80/20
Overview
• Introduction to inorganic QDs
• CdSe QDs as electron acceptor
in bulk heterojunction solar cells
• CuInSe2 QDs as electron donor
in bulk heterojunction solar cells
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First CdSe/polymer hybrid solar cells
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Device structure
P3HT
P3HT
CdSe
(TOPO/HPA)
W.U. Huynh, J.J. Dittmer, A.P. Alivisatos
Science, 295 (2002) 2425
Hybrid concept
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in bulk heterojunction devices
Effective charge separation
High interface by fabricating blends
Effective charge transport
Percolation of each component
in the interpenetrating network
Electron donor
Electron acceptors
PCBM
CdSe
[2 nm-4 nm]
First Tests
HR-TEM image of
TOPO capped CdSe
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Photovoltaic activity
Absorbance
Curren
nt [mA/cm
m2]
20 wt
wt.%
% PFT
Voltage [V]
PVT/PCBM/CdSe blends
Variation of CdSe/PCBM ratio
in 20 wt.% PFT
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Energy scheme of the device
PCBM/CdSe
0:1
0.3:0.7
1:0
0703
0.7:0.3
1:1
- Increase of photo current and open circuit voltage using CdSe QDs in organic
bulk heterojunction solar cells
Morphology studies
AFM images of PVT blends
PCBM/CdSe:0.7/0.3
PCBM/CdSe:0/1
PCBM/CdSe:1/1
PCBM/CdSe:0.3/0.7
Phase separation by increasing CdSe ratio in the blend
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IPCE depending on the size of CdSe QDs
in PFT/PCBM blends
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PCBM/CdSe:1:1
in 20 wt.% PFT
4 nm
3 nm
2 nm
Increasing the QD size leads to an increase of the photo current
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• Introduction to inorganic QDs
• CdSe QDs as electron acceptor
in bulk heterojunction solar cells
• CuInSe2 QDs as electron donor
in bulk heterojunction solar cells
Synthesis of CIS/TPP
HR TEM
HR-TEM
CIS
O
P
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O
O
CIS/TPP
5 nm
“Synthesis and characterization of nanocrystalline CuInSx for applications in organic/inorganic
hybrid solar cells” E. Arici*, N. S. Sariciftci, D. Meissner, Molecular Crystals Liquid Crystals, Vol.
383, pp 129-136 (2002).
Materials and Device Structure
CIS
O
P
O
O
CIS/TPP
PCBM
O
O
O
O
S
S
S
S
n
+
O
O
O
O
*
O
n
SO3-
*
*
S
O
n
*
SO3H
PEDOT:PSS
Poly(3,4-ethylene-dioxythiophene)
/poly(styrenesulfonate)
CuInS2 acts as electron donor/ PCBM as electron acceptor
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Thin film preparation
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AFM
from acetonitrile
50-90 nm
from Pedot:PSS (6:1)
Agglomerate size
70-120 nm
Phase seperation in thin layers(~100 nm) spin cast from PEDOT:PSS/CuInS2
dispersions leads to an increase of the agglomerate size.
CIS Hybrid Solar Cells
• Light harvesting in the range of 350-950 nm
•~ Maximum IPCE of 20 %
g the device configuration:
g
ITO/CIS+PEDOT:PSS/PCBM/LiF/Al
using
“Hybrid solar based on nanoparticles of CuInS2 in organic matrices”
E. Arici*, N. S. Sariciftci, D. Meissner, Adv. Funct. Mater., 13, 2, 165-171 (2003).
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Conclusions
•Photovoltaic activity of solution processable CdSe
and CuInS2 monolayers
•The
The prove of the concept using CdSe and CuInS2
nanoparticles in hybrid solar cells for enhanced
light harvesting
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Acknowledgements
I thank to all the collegues in LIOS
LIOS, who supported
my work in many ways!
LIOS members:
A. Mammatimin, D. Egbe, A. Workneh,
A Montaigne P Thomyonkit,
A.Montaigne,P.
Thomyonkit M.
M White,
White A.
A Pivrikas,
Pivrikas
P. Stadler, M. Bednorz,J. Gasiowski, E. Mujenovic,
K. Oppelt,M. Kruijen,A. Fuchsbauer,M. Egginger, D. Hoeglinger, G.
K l b M
Kalab,
M. Li
Lipp, H
H. N
Neugebauer,
b
N
N. S
S. Sariciftci
S i ift i
Currently founded by
Ministery of Education and Research, Elise Richter Programm,
Austria.
j
Nm. AE 3486 123
FWF Project
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