Organic Semiconductor and its applications Sara Saedinia University of California, Irvine

Today we will talk about Organic materials Advantages Disadvantages Applications Future of organic semiconductor

Organic Semiconductor (elect.) vs. Inorganic Silicon based inorganic material Covalently bonded crystals Polymer based organic material Van der Waals bonded crystals Organic electronics, or plastic electronics, is the branch of electronics that deals with conductive polymers, which are carbon based. Inorganic electronics, on the other hand, relies on inorganic conductors like copper or silicon. Covalently bonding can require high temperature -

Why Organic? Advantages Organic electronics are lighter, more flexible Low-Cost Electronics No vacuum processing No lithography (printing) Low-cost substrates (plastic, paper, even cloth…) Direct integration on package (lower insertion costs)

Why Organic? Comparison Example Cost Fabrication Cost Device Size Material Required Conditions Process Organic Electronic $5 / ft2 Low Capital 10 ft x Roll to Roll Flexible Plastic Substrate Ambient Processing Continuous Direct Printing Silicon $100 / ft2 $1-$10 billion < 1m2 Rigid Glass or Metal Ultra Cleanroom Multi-step Photolithography

Why Organic? Advantages They are also biodegradable (being made from carbon). This opens the door to many exciting and advanced new applications that would be impossible using copper or silicon.

Why not Organic? Disadvantages Conductive polymers have high resistance and therefore are not good conductors of electricity. Because of poor electronic behavior (lower mobility), they have much smaller bandwidths. Shorter lifetimes and are much more dependant on stable environment conditions than inorganic electronics would be. Intermolecular interactions are weak - Electronic bandwidths are small Prone to disorder and localization Many organic materials are extremely sensitive to oxygen and moisture

Applications Displays: RFID : Solar cells Displays: RFID : Solar cells (OLED) Organic Light Emitting Diodes RFID : Organic Nano-Radio Frequency Identification Devices Solar cells Displays: (OLED) Organic Light Emitting Diodes RFID : Organic Nano-Radio Frequency Identification Devices Solar cells

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

RFID Passive RF Devices that talk to the outside world … so there will be no need for scanners. Radio Frequency Identification Devices, or RFID, on Tags are used for item-level tracking of individual consumer goods. Such tags are expected to dramatically improve the automation, inventory control and checkout operations of products.

RFID benefits Quicker Checkout Improved Inventory Control Reduced Waste Efficient flow of goods from manufacturer to consumer Using Nano devices researchers intend to replace the cumbersome UPC barcode that is found on many products and replace it with one of these tags. Scientists are currently working on this technology to apply it to mass checkout at supermarkets, but have several minor obstacles that still must be overcome. Two of these obstacles are that each individual tag must cost less than one cent, and each RFID must function in the presence of substantial amounts of metal and radio frequency absorbing fluids. Vacuum Sublimation has allowed for excellent performance using small-molecule organic materials, resulting in circuits operating at several megahertz. Each nano-device will consist of 96 bits of information, but may contain more, such as 128 bits. The operating range for low cost devices will be limited by the power delivery from the reader to each tag. This makes the lower frequencies more appealing because they are better for power coupling. Thus, 13.54MHz looks like the most attractive frequency, however researchers are also considering the frequency at the 900Mhz range also plausible.

Solar Cells The light falls on the polymer Electron/hole is generated The electron is captured C60 The electricity is passed by the nanotube Conventional solar cells are made out of silicon. Organic Solar cells are made out of photoactive polymers in which when the light shines on it the polymer goes to the excitement state. What researchers at New Jersey IT have done is that they have used Fullerene as the backbone of Carbon nanotubes to generate electricity out of solar energy. SWNT: Single Wall Nano Tube The way it works is that the light falls on to the polymer it generates an electron and a hole. The electron is captured by the bucky ball. But it can not conduct electricity but the nanotube can do the job very well. The efficiency is still not very good compare to silicon, but the advantage as we talked about is the cost! This is a very low cost fabricated device.

Future of Organic Semiconductor Smart Textiles Lab on a chip Portable compact screens Skin Cancer treatment Smart Textiles: Interactive textiles or so-called smart fabric products are reaching the market for healthcare/medical, public safety, military, and sporting applications. These products will be designed to monitor the wearer's physical well being and vital signs such as heart rate, temperature, and caloric consumption, among many others. Smart fabrics are driven by technological improvements and increasing reliance on MEM’s based integrated sensors. Development of flexible displays comprised of OLED technologies will be integrated into clothing solutions, providing the ability to view information in real-time via wireless communications. Skin Cancer Treatment: team of researchers in Scotland has demonstrated in a pilot study that OLEDs may one day change the way photodynamic therapy (PDT) is used to treat skin cancer. In addition to the treatment of skin cancers, the researchers believe the technology could also be used in the cosmetic industry for anti-aging treatments or skin conditions such as acne. Portable Compact Screens Screens that can roll up into small devices Black and White prototype already made by Philips (the Readius™ at the bottom-left) Lab on a chip: A device that incorporates multiple laboratory functions in a single chip Organic is replacing some Si fabrication methods: -Lower cost -Easier to manufacture -More flexible

Thank You Questions?

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