### 2.4.4 Organic Semiconductors

| This is were the action is - in 2007. Organic semiconductors are hot topics in R&D, and first products in the form of OLED's are on the market. RFID's may or may not follow soon.
|  | Materials Science and technology for organic conductors and semiconductors is far from being well understood and there are major technological challenges, too. To give just one example: Oxygen, quite ubiquitous in air, is deadly for organic semiconductor devices. How can you keep a (cheap) device absolutely airtight for 20 years or so?
| But first things first: What exactly are organic semiconductors?
|  | There is no simple answer. Essentially you need two ingredients: Some organic molecule with a conjugated carbon-carbon chain. This means that there is a succession of "single bond - double bond", i.e. –C=C–C=C–C=C–C=C– with all kinds of stuff on the one remaining free valence of any C atom. There also must be some "doping" because the conjugated backbone chain of the polymer molecule is (surprisingly?!) not conductive or semi-conductive.
|  | Doping is written in quotation marks because it has nothing to do with what we have learned about doping in Si - except that you add some impurities to your semiconductor.
| We will come back to this topic later (if there is time). Meanwhile you may activate the folllwing links:
|  | Basics about semiconducting polymers The Peierls instability: Why conjugated C-chains are not conductive - contrary to expectation!

© H. Föll (Semiconductor Technology - Script)