1. Semi-conducting organic polymers and Inorganic semiconductor nano-crystals Nir Tessler EE Dept. Technion

2. The material: Organic semiconductors = molecular materials small molecules to long polymer chains. Length scale: Typical layer thickness – 50-100nm Inter chain distance ~ 0.5nm Semiconducting Organic Polymers Soluble Optoelectronic materials Nir Tessler, EE Dept., Technion Nano-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)

3. n n O O O O CN O + + = Going from green emission to red emission via simple “block” exchange Wavelength (nm) Organic LEDs one of the best sources for visible light Chemistry LEGO The original motivation

4. Organic (“plastic”) Displays A proof for the material maturity: The first known application

5. Examples from the lab Blue organic LED Organic transistor switching organic LED

6. A “Problem” Polymers emit visible light only! But optical communication elements operate with near infrared light  can’t use the low cost “plastic” technology? 5 nm PbSe 5nm InAs/ZnSe n MeO O n O Conjugated polymers OK – Lets mix

7. n=o=0.5 Mix It Organic polymer in solution Inorganic semiconductor nano-crystals in solution Mix two solutions to get the right composition

8. Using transmission electron microscope we can also “see” the 5nm crystals in the polymer matrix (i.e. the solid film)

9. Indium Arsenide nanocrystals Lead Selenide nanocrystals After mixing, the plastic polymer do not emit visible light and instead the inorganic nanocrystals emit in the near infrared (telecomm bands) A nice feature – by changing the size of the nanocrystal it is possible to tune the emission to a desired wavelength

10. Glass Ca\Al (cathode) PEDOT/ITO (Anode) n MeO O n O Polymer nanocrystal V - + Current/Energy is first injected into the polymer Energy/Charge Transfer to the nanocrystal Light Emission What happens when you place such a composite film between two electrodes?

11. 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”

12. Thanks