Transparent transistors on a postage-stamp sized glass rival some silicon based semiconductors

World's fastest organic transistor unveiled

The world’s fastest organic transistor has been unveiled paving the way for a new generation of see-through electronics.

Teams from Stanford and the University of Nebraska-Lincoln have collaborated to produce the world's fastest thin-film organic transistors that operate more than five times faster than previous examples of the experimental technology, proving these transparent semiconductors could become the foundation for cheap, high-performance displays.

Engineers have long tried to use inexpensive, carbon-rich molecules and plastics to create organic semiconductors capable of performing electronic operations at something approaching the speed of much costlier technologies based on silicon.

In a study published in journal Nature Communications, research teams led by Zhenan Bao, professor of chemical engineering at Stanford, and Jinsong Huang, assistant professor of mechanical and materials engineering at UNL described how they achieved the speed increase by altering the basic process for making the transistors.

Typically, researchers drop a special solution, containing carbon-rich molecules and a complementary plastic, onto a spinning platter – in this case, one made of glass – and the spinning action deposits a thin coating of the materials over the platter.

The new method described by the researchers involves, firstly, spinning the platter faster and, secondly, only coating a tiny portion of the spinning surface, equivalent to the size of a postage stamp.

These innovations had the effect of depositing a denser concentration of the organic molecules into a more regular alignment, which resulted in a great improvement in carrier mobility – a measure of how quickly electrical charges travel through the transistor.

The process, labelled ‘off-centre spin coating’ by the researchers, remains experimental, and the engineers cannot yet precisely control the alignment of organic materials in their transistors, or achieve uniform carrier mobility.

Regardless, even at this stage off-centre spin coating produced transistors with a range of speeds far above those of previous organic semiconductors and comparable to the performance of the polysilicon materials used in today's high-end electronics.

The researchers believe that further improvements to this experimental process could lead to the development of inexpensive, high-performance electronics built on transparent substrates such as glass and, eventually, clear and flexible plastics.

Already, the researchers have shown that they can create high-performance organic electronics that are 90 per cent transparent to the naked eye.

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