Organic electronics have power-hunger slashed

时间:2019-03-01 11:02:11166网络整理admin

By Tom Simonite Carbon-based circuits that require just one-tenth of the voltage of previous components have been developed by German researchers. Cutting the power needed to drive such circuits so dramatically could make them suitable to use in small battery-powered devices, the researchers say. Electronics made from carbon-based polymers like plastic are attractive because they can be lighter, more flexible, and less expensive to make than silicon circuitry (see Goodbye wires and silicon, hello plastic chips). “But they have to be operated with large voltages,” explains Hagen Klauk at the Max Planck Institute for Solid State Research in Stuttgart. “[This is] too high to be powered by small batteries or radio-frequency coupling like in an RFID tag.” This puts them a long way behind silicon. However, Klauk and colleagues have now found a way to make organic circuits that need one-tenth the voltage. “Most take anything from 30 to 50 volts,” says Klauk. His team cut this to between 1.5 v and 3 v. The other researchers involved were Ute Zshieshang, also at the Max Planck Institute, and Jens Pflaum and Marcus Halik at Friedrich-Alexander University, Erlangen-Nuremberg. Reducing the thickness of an organic transistor’s insulating material – known as the dielectric – made the reduction in voltage possible. “The dielectrics used in organic transistors are poor quality so they leak a lot of current and have to be made in thick layers,” Klauk explains. This, in turn, increases the voltage needed to drive the transistor. Klauk and colleagues used 2.3-nanometre-long molecules that self-assembled into an insulating layer just one molecule thick, which leaks less current, making it possible to use much lower voltages. They patterned thin-film transistors – commonly used to make flat-screen displays – and logic gates on top of aluminium. The molecules for the insulating layer were dissolved in propanol to be added to the circuits. As the propanol evaporates, the molecules form a layer in which the molecules are aligned. Two different kinds of organic semiconductor were used. They also created circuits on top of flexible transparent plastic. Attempts to make RFID tags from organic electronics have previously been hampered by the power-demand problem, says William Eccleston, at Liverpool University, UK. “These presumably wouldn’t have that problem,” he says. “The results look exceptionally good.” Klauk believes the technique could be crucial if organic electronics are to make it into handheld consumer devices. “If I give you a transistor and it needs a 20 v battery, you’re stuck,” he explains. “But if I give you one that works at 3 volts it is easy to see that you just need two small 1.5 volt batteries.” Journal Reference: Nature (vol 445,