Researchers at Oregon State University and Hewlett Packard have reported their first example of an entirely new class of materials which could be used to make transparent transistors that are inexpensive, stable, and environmentally benign. This could lead to new industries and a broad range of new consumer products, The possibilities include electronic devices produced so cheaply they could almost be one-time "throw away" products, better large-area electronics such as flat panel screens, or flexible electronics that could be folded up for ease of transport. Findings about this new class of "thin-film" materials are called amorphous heavy-metal cation multicomponent oxides.
This is a significant breakthrough in the emerging field of transparent electronics, experts say. The new transistors are not only transparent, but they work extremely well and could have other advantages that will help them transcend carbon-based transistor materials, such as organics and polymers, that have been the focus of hundreds of millions of dollars of research around the world. Compared to organic or polymer transistor materials, these new inorganic oxides have higher mobility, better chemical stability, ease of manufacture, and are physically more robust. Oxide-based transistors in many respects are already further along than organics or polymers are after many years of research, and this may blow some of them right out of the water.
Advances Made In Transparent Electronics:
Significant advances in the emerging science of transparent electronics, creating transparent "p-type" semiconductors that have more than 200 times the conductivity of the best materials available for that purpose a few years ago. This basic research is opening the door to new types of electronic circuits that, when deposited onto glass, are literally invisible. The studies are so cutting edge that the products which could emerge from them haven't yet been invented, although they may find applications in everything from flat-panel displays to automobiles or invisible circuits on visors.
Most materials used to conduct electricity are opaque, but some invisible conductors of electricity are already in fairly common use, the scientists said. More complex types of transparent electronic devices, however, are a far different challenge - they require the conduction of electricity via both electrons and "holes," which are positively charged entities that can be thought of as missing electrons.
These "p-type" materials will be necessary for the diodes and transistors that are essential to more complex electronic devices.Only a few laboratories in the world are working in this area, mostly in Japan, the OSU scientists. As recently as 1997, the best transparent p-type transparent conductive materials could only conduct one Siemen/cm, which is a measure of electrical conductivity. The most sophisticated materials recently developed at OSU now conduct 220 Siemen/cm.
These are all copper oxide-based compounds that we're working with. Right now copper chromium oxide is the most successful. Researchers continue to work with these materials to achieve higher transparency and even greater conductivity.