Green printing technology has enabled researchers at NEC Corp. to fabricate high-speed carbon nanotube transistors on inexpensive flexible polymer substrates. NEC claims its nanotube transistors are 100 times faster that competing flexible organic transistors, while its printing technique produces 90 percent fewer greenhouse gases than silicon transistors. NEC presented its research results last week at the International Nanotechnology Exhibition & Conference last week in Tokyo. Organic transistors enable circuitry to be printed at room temperature on flexible polymer substrates, vastly lowering chip manufacturing costs compared to the high-temperature chemical vapor deposition processes. Low-temperature processing also produces less C02 gas, uses less water and produces fewer toxic byproducts than traditional silicon chip processing. However, the electron mobility of organic transistors is dismal compared to silicon. NEC also claims to have combined the high-speed of carbon nanotube transistors with the low-temperature processing, resulting in transistors that are printable on organic substrates with electron mobilities 100 times greater than typical organic transistors.