Organic Electronics

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Organic Electronics
Presented by Babak Zamanlooy Advanced VLSI
Course Instructor Prof. S. M. Fakhraei
University of Tehran, Electrical and Computer
Engineering Faculty December 2006 Class
Presentation for Educational Purposes
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Outline

• Introduction
• Organic Transistors
• Organic Light Emitting Diode
• Fabrication Techniques
• Conclusion

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Introduction

• Low cost
• Lower temperature manufacturing (60-120 C)
• Light weight
• Mechanical flexibility
• Large area
• Low mobility
• High voltage operation
• Low Reliability

Advantages
Challenges
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Introduction

• Applications
• Flexible low-weight large-Area displays
• RF ID TAG

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Organic Transistors

• Organic transistors are transistors that use
  organic molecules rather than silicon for their
  active material.

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Organic Thin Film Transistors

• Top contact devices have been reported to have
  superior performance for certain organic
  semiconductors compared with their bottom contact
  counterparts.

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Materials
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Charge Transport in Organic Materials

• Organic materials have the ability to conduct
  charge (holes and electrons) due to the p-orbital
  overlap of neighboring molecules.
• On a downward positive electron binding energy
  scale, there is the highest occupied molecular
  orbital (HOMO) and a lowest unoccupied molecular
  orbital (LUMO) with an energy gap in between.
• A model that is often used to describe organic
  semiconductors explains transport between
  molecules is hopping 6.

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Charge Transport in Organic Materials
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Organic FET SRAM
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Control of Threshold Voltage
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Organic Light-Emitting Diodes

• The flat-panel display technology is currently
  dominated by liquid-crystal technlogy
• Will OLEDs fare any better against LCDs?

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Device Structures
Cathode
Cathode

• Single layer device
• Multilayer device

Metal
ETL
Metal
HTL
HTL ,ETL
ITO-Covered Substrate
ITO-Covered Substrate
Transparent Anode
Transparent Anode
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Degradation

• Oxidation
• Black spot
• Electrical shorting

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Organic Devices Fabrication Techniques

• Spin coating
• Inkjet printing

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• Spin Coating

Load substrate
Dispense resin
Spin
Drying
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Inkjet Printing
Comparison of spin coating and inkjet printing
technologies
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The Polymer Light Emitting Logo Fabrication
Process

• Preparation of the substrate
• Polymer printing
• Deposition of the luminescent polymer and the
  cathode material.

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Conclusion

• Electronics based on organic transistors is
  steadily progressing towards higher levels of
  integration and better performance.
• The main advantages offered by organic transistor
  technology are the capability to cover large
  areas even on thin, flexible substrates (due to
  the low temperatures involved) and the low cost
  of the manufacturing process.
• OTFTs are not suitable for use in applications
  requiring very high switching speeds

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References
1 Paul Meredith , A Soft Future Available
http//ww.softsolids.physics.uq.edu.au 2
Qintao Zhang and Sha Li, Investigation of the
Potential of Organic Circuits Available
http//www.bwrc.eecs.berkeley.edu/Presentations
3 Joseph E. T. Peach, Organic transistors
Available http//www. students.washington.edu/je
tpeach 4 Gilles Horowitz ,Organic transistors
Available http//www.tima.imag.fr/conferences/pol
ytronic 5 C.D.Dimitrakopoulos and D.J.Mascaro
,Organic Thin film transistorsa review of
recent advances, IBM J. RES. DEV,vol.45,pp.
11-
27, January
2001 6 E. Cantatore and E.J. Meijer,
Transistor operation and circuit performance in
organic Electronics IEEE,2003. 7 Nir Tessler
and Evin Mackenzie, Device Physics, charge
transport, applications and processing in organic
electronics Available http//www.ee.technion.ac.
il/orgelect 8 Makoto Takamiya et al.,An
Organic FET SRAM for Braille Sheet Display with
Back Gate to Increase Static Noise Margin ISCC
2006. 9 Shingo Iba et al., Control of
threshold voltage of organic field-effect
transistors with doublegate structures Applied
Physics Letters, 2003. 10 John Campbell Scott,
and George G.Malliaras , The Chemistry,Physics
and Engineering of Organic Light-emitting diodes
Wiley,2000 11 Spin Coat Theory
Available http//www.cise.columbia.edu/clean/proc
ess 12 Jayesh Bharathan, and Yang Yang,
Polymer Electroluminescent Devices Processed by
Inkjet Printing, Applied Physics
Letters,vol.72,No.21,1998. 13 T. R. Hebner, C.
C. Wu, D. Marcy, M. H. Lu, and J. C. Sturm,
Ink-Jet Printing of Doped Polymers for Organic
Light Emitting Devices,Applied Physics Letters
,vol.72,No.5,1998.
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Thanks for your attention