Organic Solar Cells - WordPress.com
Transcript of Organic Solar Cells - WordPress.com
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Organic Solar Cell
• 1977 discovery of conductive polymer
• 1986 the first organic photovoltaic cell (<1%)• 2013 > 12%
Nobel Prize in Chemistry 2000
C.W. Tang, Appl. Phys. Lett., 48 (1986) 183-185R.F. Service, Science, 332 (2011) 293
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Fast Recent Growth
3.0%
5.4%6.4%
7.9% 8.3%9.2%
10.6%
12.0%
2%
4%
6%
8%
10%
12%
2006 2007 2008 2009 2010 2011 2012 2013 2014Year
Effic
ienc
y
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Advantages• Lightweight• Transparent• Flexible• Low cost
Challenges• Efficiency• Stability• Scale up
roll-to-roll printing, Konarka
Threshold• 7%• 7 years
G. Dennler et al., Adv. Mater., 21 (2009) 1323-1338.
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Conductive Polymer• How does a polymer mimic a metal?
delocalized π-electrons• Conjugated polymer
a system of connected p-orbitalswith delocalized electrons using alternating single and multiple bonds
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Ethylene (C2H4)
• Frontier orbitals
• Band gap
• Just like conductionband and valenceband
LUMO
HOMO
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Device Physics: HOMO, LUMO
• HOMO, highest occupied molecular orbital~ valance band maximum
• LUMO, lowest unoccupied molecular orbital~ conduction band minimum
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Device Physics
G. Li et al., Nat. Photonics, 6 (2012) 153-161
1.Absorb & Photoexcitation → exciton (e--h+ pair) in polymer
2.Exciton diffusion to polymer-fullerene interface
3.Charge Transfer → e- and h+
4.Recombine or drift to electrodes
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1. AbsorptionNew Materials
J. Peet et al. Nat. Mater. 6, 497-500 (2007).
P3HT
PCPDTBT
Low Bandgap
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2. Exciton Diffusion
Morphology control
J. Peet et al., Nat. Mater., 6 (2007) 497-500.
1,8-octanedithiol
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3. Charge SeparationSpin manipulation
Y. Zhang et al., Nat. Commun., 3 (2012) 1043
with spin
without spin
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4. Charge Collection (cont.)
Extra doped electrode layer
Ryu, M. S. et al. Sol. Energy Mater. Sol. Cells 95, 1896-1900 (2011)