In recent years we saw electronic devices including batteries and light-emitting diodes made of paper instead of glass or plastic. Now, the latest innovation in the field of electronics uses transparent and smooth paper to fabricate transistors.
This was made possible due to the property of paper to absorb inks, which contain pigments used to print or electronic materials like carbon nanotubes and semiconducting polymers.
In order to make paper-based circuits that can control displace, material scientists have to firstly print transistors, which perform optimally. The electrons have to move through a thin layer of semiconducting materials, which are only a few nanometers thick. In addition, the paper has to be as smooth as possible, so that the electron flow of the device is not interrupted.
Liangbing Hu, a materials scientist at the University of Maryland, College Park managed to overcome these limitations and created printed transistors using nanopaper. This material contains nanoscale fibers, which produce an even surface and do not interrupt the flow of light.
For his work, Hu and his team created their own nanopaper, by treating paper pulp with oxidizing chemicals.
The transistors were built on the paper by depositing a layer of three materials: carbon nanotubes, insulating organic molecule and semiconducting organic molecule. The device was completed with electrodes made by laying down carbon nanotubes. These were also the structural backbone that kept the paper smooth.
The transistors are 84% transparent with almost constant performance. But Hu is convinced that he can improve the performance further, by decreasing the wrinkling.
The invention brings material science one step closer to creating the renewable printed electronics, according to Jeffrey Youngblood, a materials engineer at Purdue University.