Semiconducting organic polymers

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Semi-conducting organic polymers and Inorganic
semiconductor nano-crystals
Nir Tessler
EE Dept. Technion
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Semiconducting Organic Polymers
The material Organic semiconductors
molecular materials small molecules
to long polymer
chains. Length scale Typical layer thickness
50-100nm
Inter chain distance 0.5nm
Soluble Optoelectronic materials
(they come as powder or fibers. We dissolve them
in the appropriate solvent and cast them from
solution. We usually design it such that after
drying we get 0.1micron thick solid film)
Nano-Materials
Nir Tessler, EE Dept., Technion
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The original motivation
Chemistry LEGO


CN

Organic LEDs one of the best sources for visible
light
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The first known application
Organic (plastic) Displays
A proof for the material maturity
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Examples from the lab
Organic transistor switching organic LED
Blue organic LED
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A Problem Polymers emit visible light only!
But optical communication elements operate with
near infrared light ? cant use the low cost
plastic technology?
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Mix It
Inorganic semiconductor nano-crystals in solution
Organic polymer in solution
no0.5
Mix two solutions to get the right composition
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Using transmission electron microscope we can
also see the 5nm crystals in the polymer matrix
(i.e. the solid film)
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After mixing, the plastic polymer do not emit
visible light and instead the inorganic
nanocrystals emit in the near infrared (telecomm
bands)
Indium Arsenide nanocrystals
Lead Selenide nanocrystals
A nice feature by changing the size of the
nanocrystal it is possible to tune the emission
to a desired wavelength
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What happens when you place such a composite film
between two electrodes?
Ca\Al (cathode)
Polymer
-
V

nanocrystal
PEDOT/ITO (Anode)
Glass
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The potential Impact
The telecomm experts say that for the fiber to
the home to happen they need low cost components
that can be afforded by any household. ? Use
plastics
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Thanks