Organic Solar Cells - WordPress.com

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1 Organic Solar Cells MSE/ECE 5050/6050/6961 Guest lecturer: Ye Zhang, Ph.D.

Transcript of Organic Solar Cells - WordPress.com

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Organic Solar Cells

MSE/ECE 5050/6050/6961Guest lecturer: Ye Zhang, Ph.D.

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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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Products

Pictures: Solarmer

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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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Molecular Orbital (MO)

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Ethylene (C2H4)

• Frontier orbitals

• Band gap

• Just like conductionband and valenceband

LUMO

HOMO

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Lab Device

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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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Efficiency

1. Absorption2. Exciton diffusion3. Charge separation4. Charge collection

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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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1. Absorption (cont.)Plasmon Enhancement

W. Bai et al. , Opt. Express 2010, 18, A620–A630

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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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2. Exciton Diffusion (cont.)

Y. Yao et al., Adv. Funct. Mater., 18 (2008) 1783-1789.

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3. Charge SeparationNanoparticle

Wu, J.-L. et al. ACS Nano 5, 959-967 (2011)

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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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3. Charge Separation (cont.)

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4. Charge Collection

Electrode properties

J.-H. Huang et al., ACS Nano, 5 (2011) 6262-6271.

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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)

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Trend: Tandem cell

You, J. et al. Nat. Commun. 4, 1446 (2013)