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Chapter 2. Organic semiconductor devices
1. Organic light-emitting diodes (OLED)
2. Thin-film transistors (TFT)
3. Photovoltaic cell
4. Bio-sensor
5. FRID tag
(solar cell)
Organic Electronics
Light emitting diod (LED)
An organic passive-matrix display on a substrate of polyethylene terephthalate, a
lightweight plastic, will bend around a diameter of less than a centimeter. The 18mm-thick, 5-by-10-cm monochrome display consists of 128 by 64 pixels, each
measuring 400 by 500 µm, and is being operated at conventional video brightness of
100 cd/m2. It was fabricated by Universal Display Corp., Ewing, N.J., with a
moisture barrier built into the plastic that prevents degradation of the pixels.
Eastman Kodak and Sanyo Electric developed this active-matrix, full-color organic
display, only 1.8 mm thick, for digital still and video cameras and other portable
imaging products. With a 2.4-inch diagonal screen and integrated drive electronics,
the bright display has 852 by 222 pixels, a contrast ratio of more than 250:1, and a
peak luminance of 200 cd/m2.
Work function: the energy needed to move an electron from the Fermi energy level into vacuum
Ionization potential: the energy required to remove an electron from the isolated atom or ion
Electron affinity: the energy given off when a neutral atom in the gas phase gains an extra
electron to form a negatively charged ion
Displays (OLED)
• One of the biggest applications of organic transistors right
now.
Organic TFTs may be used to drive LCDs and potentially
even OLEDs, allowing integration of entire displays on
plastic.
• Brighter displays
• Thinner displays
• More flexible
Field effect transistor (FET)
n-channel vs. p-channel
Organic thin-film transistors (OTFTs) are constructed of an organic or
inorganic gate insulator and an organic semiconducting channel linking
the source and drain.
Organic thin film transistor
Pentacene
photovoltaic cell
The same device preparation procedure can be used to produce a
photovoltaic cell, a device that converts light into voltage (or current).
A solar cell, made from a
monocrystalline silicon wafer
Solar Cells
• The light falls on the polymer
• Electron/hole is generated
• The electron is captured C60
• The electricity is passed by
the nanotube
Bio-sensor
a
b
PCR-amplified DNA fragments
Complementary probes (resulting in Au-np aggregation)
Noncomplementary probes (preventing Au-np aggregation)
Excess PCR primers
RFID
• Passive RF Devices that talk to the outside world … so there will
be no need for scanners.
• Quicker Checkout
• Improved Inventory Control
• Reduced Waste
• Efficient flow of goods from
manufacturer to consumer
What’s next For RFID? Chips Based On Printable Organic
Semiconductors?
“Cheap, smart, thin and eventually
completely disposable.”
Organic Semiconductor Conference
program, Cambridge, UK, 2003
www.polyic.com