A
polymer
that matches the electrical performance of amorphous silicon has been
discovered by researchers in Britain and the US and could lead to a cheap way to
make electronic paper.
Amorphous (ie non-crystalline) silicon is electronically sluggish compared
with the more structured form used to make the transistors in a computer
processor.
But it has the advantage of being relatively easily to deposit over large
areas, and is commonly used to create the matrix of thin-film transistors (TFT)
that drive most LCD displays.
Companies such
as Plastic
Logic in Cambridge have been
developing
organic (ie carbon based) materials , with silicon-like
semiconductor properties, that promise less-expensive ways to do the same job.
The materials can be made up into inks so that transistors and entire
circuits can be printed out by inkjet – or, for mass-production of larger
surfaces, gravure press.
The new polymer, reported in the April Edition of
Nature
Materials, is said to have six times the electronic performance of any
previously reported for these materials. It was developed at the Merck
laboratories at Southampton, and by researchers at
Stanford
and other California establishments.
Iain McCulloch, project manager at
Merck,
says a primary motivation of the research was to reduce manufacturing costs,
because the use of amorphous silicon required high temperatures and high-vacuum
processes producing a lot of waste products.
But polymer semiconductors are also compatible with plastic substrates which
could 'enable a new generation of flexible, lightweight and ultimately large
area displays'.
They can also be used to print simple logic circuits so they may be seen
first in disposable novelty electronic items, followed by small reflective PDA
displays or e-paper, and posters.
'Further away are large, high resolution displays such as active-matrix LCD
or OLED (organic light emitting diode), and possibly even item level RFID
tags,' McCulloch told Nature.
He added: 'The first demonstrator products are already here and the
commercial possibilities are encouraging.'
One problem the new materials will not solve is that of notebook battery
life. Polymer displays will draw as much power as those with a silicon matrix.