Universität Karlsruhe (TH)

1Organic Semiconductors

ϕA + ϕB

ϕA - ϕB π∗, LUMO

π, HOMO

Energies with high density of states can be treated likeenergy bands in inorganic semiconductors

Overlapping orbitals ϕA und ϕB

E

Universität Karlsruhe (TH)

2Polymer solar cells

P3HT:PCBM

PEDOT:PSS

Cathode200 nm

Substrate (Glass)

Absorber200 nm

Hole conduction20 nm

Anode (ITO)125 nm

Universität Karlsruhe (TH)

3Polymer solar cells

-

+

EB = 0,4…1,4 eV

-

Bilayer Heterojunction Bulk Heterojunction

Universität Karlsruhe (TH)

4

Preliminary schedule

1. Introduction, The Sun2. Semiconductor fundamentals3. Solar cell working principles / pn-junction solar cell4. Silicon solar cells5. Copper-Indiumdiselenide solar cells6. Cell optimization and highly efficient device concepts7. Modules and system integration8. Organic photovoltaics9. Dye sensitized solar cells

10. Economics and profitability11. Other renewable energies12. Excursion

Course schedule

Universität Karlsruhe (TH)

5Cathode replacement with n-doped layers

[Colsmann et al, SPIE Proc 6192:6192-95 (2006)]

E

BPhen

Li

Universität Karlsruhe (TH)

6Transparent devices

[Source: ZSW, Stuttgart, 2007]

LiF interfaces lead to local n-doping

Universität Karlsruhe (TH)

7Transparent devices

Au/Alη = 0,73%

BPhen:Li / PH750 / Au / Alη = 1,01%

BPhen:Li / PH750η = 0,62%

[Source: Felix Nickel, Project work, LTI, 2007]

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8Tandem solar cells

Polymer cell (P3HT)

Vacuum processed (CuPc)

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9Tandem solar cells

Recombination zone

Metall contacts are opaque

Gold particles between (doped)charge carrier transport layers

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10Tandem solar cells

Band scheme

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11Tandem solar cells

jV Charcteristics

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12Simulations

Simulations mandatory! …(Transfermatrix method)

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13Simulations

Fine adjustment of the optical field by n-doped transport layers

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14

Ellipsometry

Seebeck measurements

---

T2T1

T1 < T2

Simulations

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15

η = 6,5 %

Tandem solar cells

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16Tandem solar cells

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17

Up to 7monolithicallystacked cells

Tandem solar cells

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18Tandem solar cells

Universität Karlsruhe (TH)

19Tandem solar cells

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20Tandem solar cells

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21Tandem solar cells

Universität Karlsruhe (TH)

22Infrared absorbing molecules

S

N

S

NS

N

nC12H25

PTPTB

S S

NS

NEHEH

n

PFDTBT

Donor + Acceptor internal charge transfer complexin which the whole polymer

actsin the solar cell as a

electron donorHOMO

HOMO

LUMO

LUMO

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23Infrared absorbing molecules

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24Modules

Modul-Verschaltung