Silicon Transistors and Plastic Equal Flexible Displays

In a groundbreaking innovation that could see the widespread adoption of plastic-based bendable displays, researchers at a company called Phicot have managed to develop a new method of printing silicon transistors on flexible plastics. This could finally erase the obstacles plaguing the industry, the largest of which is the fact that producing error-free flexible displays at industrial scales is currently impossible. The new devices are a lot lighter, and also more rugged and robust, than their glass-based counterparts, Technology Review informs.

The new manufacturing process is relatively similar to the one currently used by companies producing cheap solar cells. In fact, Phicot's parent corporation, Ames-based PowerFilm, has been producing solar cells based on this technology for some time. The process is relatively straightforward. Long sheets of plastic are fed through an ensemble featuring rolls, and then large amounts of amorphous silicon transistors are deposited on the sheets. The roll-to-roll process is already working effectively in solar-cell production, and engineers see no reason why it shouldn't be just as useful in flexible-display production.

“The basic technology of roll-to-roll can bring the price down and make plastic an excellent option for the back half of the display,” the CEO and Co-founder of PowerFilm, Frank Jefferey, explains. He adds that, at this point, most display manufacturers rely on using polysilicon, a material that allows for the fast transfer of electrons through the screen, but require large temperatures to be deposited. Naturally, these high temperatures melted plastic, so the Phicot team turned to amorphous silicon for help. These materials can efficiently transmit electrons to control electrophoretic displays such as E-Ink, and maybe even the pixels of organic light-emitting diode (OLED) displays. The thing about the system is that this type of silicon can be deposited at room temperature.

The production process for this innovation is split between Phicot and a facility belonging to HP Labs. The former sends the plastic sheets laden with amorphous silicon to the latter, where a special process is used to etch transistors atop the chemicals. The method used at the Bell Labs is an adaptation of an existing technique, called lithography. In order to make etching on plastic possible, scientists created the self-aligned imprint lithography (SAIL), which is thus far the only method of etching the transistors successfully.