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Organic Electronics
Yousof Mortazavi
VLSI Course PresentationDecember 2004
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References
L. Ficke,M. Cahay, The bright future of organic LEDs, IEEE Potentials,
Jan. 2004. J. N. Bardsley, International OLED technology roadmap, IEEE J. SelectedTopics in Quantum Electronics, Vol. 10, No. 1, Feb. 2004.
T. Y. Winarski, Patenting bright ideas; the current state of patentedtechnology in the field of organic light emitting diodes, IEEE Circuits andDevices Magazine, Apr. 2004.
T. Shimoda, T. Kawase, All-polymer thin film transistor fabricated by high-
resolution ink-jet printing, In Proceedings IEEE International Solid-StateCircuits Conference, 2004. S. Forrest, P. Burrows, M. Thompson, The dawn of organic electronics,
IEEE Spectrum, Aug. 2000. G. Schmid, et al., Organic electronics: perspectives towards applications,
ISSCC 2004. K. Nomoto, et al., A bottom-contact organic-thin-film-transistor for flexible
display application, ISSCC 2004. M. G. Kane, Organic electronics: what is it good for?, ISSCC 2004. D. Gundlach, et al., High-mobility, low voltage organic thin film transistors,
IEDM 1999.
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Outline
Motivations OLED Fundamentals OTFTs
Advantages of Organic Electronics Applications OLEDs for Color Displays
Challenges
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Motivations
Microelectronics vs. Macroelectronics: Microelectronics: try to make smaller
transistors to reduce cost and boostperformance Macroelectronics: reduce costs in order build
ever larger devices, with acceptableperformance
Thin Film Transistors: Active layer is silicon (a-Si) deposited on
glass . For high mobilities, a-Si can be crystallized (p-
Si) by laser-pulses at high temperatures. Cant easily use flexible substrates, such as
plastics
Organic Thin Film Transistors Organic semiconductors were discovered in
1987. Organic compounds are a natural match for
plastic substrates.
Use of polymers allows large-areas to becoated and patterned without conventionalphotolithography (e.g. spin-coaters and ink-jetprinters).
Organic TFTs may be made large or small(30 nm @ Cornell U.)
Cost/area Cost/function
Bulk Si ICs $10K/ft2100 cents/transistor
a-Si TFTs onglass $150/ft2
1 mcents/transistor
PrintedOrganic TFTs $30/ft2
200 cents/transistor
[Kane (ISSC04)]
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OLED Fundamentals
In 1987, Tang, et al.published Organicelectroluminescentdiodes.
Currently more than 500U.S. Patents have been
issued on organicelectronics. Challenges:
Choice of anode for ohmiccontact (for low voltagedevices)
Diffusion of In, O into HTL HIL interface betweenITO and HTL
Protection from oxygen andwater encapsulation
ITO-Covered Substrate
HTL
ETL
Metal
Cathode
Transparent Anode
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OTFT (OFET)
Typical OTFT:
Bottom gate, inverted staggeredstructure Pentacene (C22H14) active Gate dielectric
SiO2 PMMA PVP
OTFTs operation: accumulation depletion
Mobilities as high as 1 cm2/Vs hasbeen obtained with Ion/Ioff ratio of108.
Very low fabrication temperature
(
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Advantages of Organic Electronics
Thin, lightweight, flexible
displays Low voltage, low power,
emissive source High brightness Broad color gamut
Wide viewing angle (~180) Good contrast High resolution (
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Applications
Flexible Displays PM-OLED AM-OLED Wearable Displays
Sensor Arrays Artificial Skin Gas Sensors
RF ID Tags Inductors Capacitors
X-ray imaging panels
Solid-State Lighting
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OLEDs for Color Displays
[Forrest, et al.]
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Challenges
Choice of electrodes Encapsulation Reliability and yield Lifetime Brightness control
with feedback Particle migration
control with AC driver
A. Giraldo, et al.
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Thank You
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