TECHNOLOGIES FOR MANUFACTURING LARGESCALE POLYMER SOLAR CELLS

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
FINAL PRESENTATION March 7th, 2002 MULTI
DISCIPLINARY PROJECT GROUP 2
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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Team members of Multi Disciplinary Group 2 Evert
de KoeijerJaap Smits Jeroen HuijbersJoris
Wouters Maikel van Iersel (project leader)Paul
Hamelinck Yu Hong Tam (treasurer) Tutor
Drs. Willem Posthumus Principal Prof. dr.
ir. René A.J. Janssen
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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Contents

• Introduction
• Approach
• How does a solar cell work?
• Structure of polymer solar cell
• 23 techniques investigated
• Selection on 8 criteria
• Research on 4 selected techniques
• Costs and Efficiency
• Environmental aspects
• Financial status of MDP

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Introduction
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POLYMER SOLAR CELLS
Approach
Phase I Research on different layers of solar
cells Phase II Investigating production
techniques for upscaling Phase III Selection and
comparison of suitable techniques Phase IV
Comparison of suitable techniques with
non-organic solar cells
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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
How does a solar cell work?
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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Structure of polymer solar cell
Light (photons)
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POLYMER SOLAR CELLS
Substrate and ITO

• Substrate Glass or PET
• PET Flexible, but diffusion of water and oxygen
• Glass inflexible
• ITO (Indium Tin Oxide)
• transparent conductor, serves as cathode for
  the solar cell
• expensive, cheaper alternatives have low
  quality
• ITO on substrate (glass or PET) is
  commercially available

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Polymer layers

• PEDOT/PSS
• Conducting Polymer
• Smoothens ITO-layer
• Hole collector
• Dispersion in water

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Polymer layers

• PPV/PCBM
• Photoactive Layer
• PPV electron donor
• PCBM electron acceptor
• Solution in organic solvent (toluene)

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POLYMER SOLAR CELLS
Aluminum

• Anode for the solar cell
• High conductance
• Deposited with vacuum evaporation

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
23 techniques investigated!
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POLYMER SOLAR CELLS
Selection on 8 criteria

• Applicable to which layer?
• Layer thickness 100 nm
• Temperature lt 200 ºC
• Costs
• Area
• Layer homogeneity
• Industrial experience
• Need for polymer/molecular adjustment

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Four selected techniques

• Self-assembling
• Screen printing
• Doctor blading
• Ink jet printing

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Self-assembling

• Layer-by-layer
• Oppositely chargedpolyelectrolytes
• Dipping, rinsing, drying
• Deposition of bilayers at a time

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POLYMER SOLAR CELLS
Self-assembling

• Parameters
• pH
• Adsorption kinetics
• Counterions
• Ionic strength

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POLYMER SOLAR CELLS
Self-assembling

• PEDOT/PSS
• Self-assembled directly anionic PSS and
  positively charged PEDOT
• NaCl is added to fix the final ionic strength
  pH is adjusted
• PPV/C60
• pPPV/(PAA-) (poly(acrylic acid)-) precursor of
  PPV
• C60-/(PAH) (poly(allylamine hydrochloride))
• PPV/SPS- and C60/C60-
• PPV/C60-

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Self-assembling

• Advantages
• Any oppositely charged species can, in any order,
  be adsorbed layer-by-layer
• Proceeds at ambient temperatures
• Technique processable from aqueous solution
• Good control of thickness and composition
• Energy-efficient procedure

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POLYMER SOLAR CELLS
Self-assembling

• Disadvantages
• Extremely time-consuming
• Most polymer or molecule structures used have to
  be adjusted for using the polyelectrolyte
  self-assembling technique
• Counterpolyelectrolyte remains in the device and
  influences behaviour and performance of device
• Multilayers parallel to the substrate bad
  influence on the electron transfer and mobility
  of electrons.
• No experience in mass-production

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Screen printing

• Squeegee presses ink into screen
• Squeegee brings screen and ink in contact with
  substrate
• Ink is attracted to substrate
• When squeegee passes by, screen releases
  substrate
• Ink leaves screen and stays on substrate
• Ink flows out

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Screen printing

• Parameters
• Ink
• Viscosity
• surface tension
• speed of solvent evaporation
• Squeegee
• durometer (hardness)
• speed
• pressure
• Screen
• nominal thread diameter
• mesh count

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POLYMER SOLAR CELLS
Screen printing

• PEDOT/PSS
• 1-2 weight- polymer dispersion
• screen 120 threads/cm, thread diameter 3 mm
• PPV/PCBM
• 1-2 weight- polymer solution
• screen 181 threads/cm, thread diameter 3 mm

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Screen printing

• Advantages
• Applicable for any soluble or dispersible polymer
• Smooth areas possible (lt5 nm deviation)
• Large areas possible (up to 1 m2)
• Low cost equipment
• Proceeds at ambient temperatures
• Possible in semi-continuous process

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POLYMER SOLAR CELLS
Screen printing

• Disadvantages
• Screens have to be cleaned often
• Ink on the screen can pick up contamination
• Many parameters for tuning layer thickness and
  smoothness

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TECHNOLOGIES FOR MANUFACTURING LARGE-SCALE
POLYMER SOLAR CELLS
Doctor blading

• Doctor Blading is also known as tape casting or
  knife coating
• Published and patented in 1952
• by Glenn Howatt
• Initially used in ceramic
• industry

• Polymer is cast on substrate
• The Doctor removes excess substance

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POLYMER SOLAR CELLS
Doctor blading

• Parameters
• Evaporation rate of the solvent
• Viscosity of solvent
• Process velocity
• Contact angle
• Height of the blade above the substrate
• Each polymer/substrate combination requires
  another optimum.

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Doctor blading

• Advantages
• Few operations and energy are required
• Proceeds at ambient temperature
• No degradation of the multilayer organisation
  occurs with successive depositions
• Roll-to-roll process possible

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POLYMER SOLAR CELLS
Doctor blading

• Disadvantages
• Low homogeneity for surfaces gt 20x30 cm2
• Deposition is only possible on flat surfaces
• Each application requires a different mixture of
  parameters
• Loss of material

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POLYMER SOLAR CELLS
Ink jet printing
Nozzle

• Drop-on-demand
• Piezoelectric principle

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Ink jet printing

• Parameters
• Viscosity of ink (dispersion or solution with
  polymers)
• Surface tension of ink
• Concentration of polymer solution
• Type of substrate
• Diameter of nozzle and droplets

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Ink jet printing

• Advantages
• Large surfaces
• High quality films, small deviations
• No loss of material
• Various range of different solvents
• Already some industrial experience (pilot
  production of PLED's)

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Ink jet printing

• Disadvantages
• Great amount of solvent needed (toluene)
• Low viscous ink needed
• Technique is too precise for solar cells in
  comparison with the PLED's

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Conclusion techniques

• Less preferable
• Self-assembling
• Doctor blading
• Preferable
• Screen printing
• Ink jet printing

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Efficiency and costs

• Efficiency
• Polymer solar cell 2.5
• Silicon solar cell 15
• Costs polymer solar cells
• Material costs
• Production costs
• Material costs
• Polymer solar cell 5 ?/Wp
• Silicon solar cell 0.5 ?/Wp

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POLYMER SOLAR CELLS
Environmental aspects

• Indium
• Limited Indium available
• Indium most toxic component of solar cell
• Toluene
• Toluene used during process also toxic
• Approx. 17 gram/m2

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POLYMER SOLAR CELLS
Special thanks to René Janssen Jeroen van
Duren Willem Posthumus
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