Two-dimensional transistors on thin-film materials could be so cheap they would be literally disposable

By Brian Santo, contributing writer

While video display manufacturers are furiously trying to devise a practical
means to manufacture thin film transistors (TFTs) with the goal of reducing the
cost of monitors, TVs, smartphone screens, and the like, a group of researchers
in Ireland have just announced a printing process for creating two-dimensional
transistors on thin-film materials that could make displays so cheap
they would be literally disposable.

A possible application might be packaging for perishables (e.g., a container
of yogurt) that displays an expiration-date countdown. Or white wine labels
that alert you when the contents are the optimum temperature for drinking. Or
imagine if the wrapping for your 7-11 breakfast burrito could alert you when
your bus or your Lyft is about to arrive. 


AMBER researchers made a major
breakthrough in smart printed electronics. Image source: AMBER.

The development of the new thin film transistors was done at Advanced
Materials and BioEngineering Research (AMBER)
, an organization that focuses
on materials sciences; it’s funded by Science Foundation Ireland.

AMBER researchers believe they’re the first to actually print 2D transistors
– they say they are using a “standard” printing process. They said it was
important to show it was possible to make transistors this way, which is why
they did that first, but they seem certain they’ll be able to use the same
process to build solar cells, LEDs, and other devices.

They described their transistors as vertically stacked, with graphene
source, drain, and gate electrodes, a transition metal dichalcogenide channel,
and a boron nitride separator. The description comes from the summary of a
paper recently published in the journal Science

The specific chalcogenide AMBER said it’s using is tungsten diselenide. It
was selected because it has a high charge-carrier mobility.

The transistors rely on electrolytic gating with ionic liquids, which the AMBER
researchers said leads to higher operating currents than achieved with
comparable organic TFTs. Electrolytic gating has only recently been proposed
for oxide thin films. (Selenium is a chalcogen – chalcogens are also known as
the oxygen family).

The upshot is that the materials AMBER has chosen for its printed TFT
devices carry higher currents than most other TFTs at relatively low drive

There are a number of other potential applications for TFT-based displays
that may end up as cheap as AMBBER promises. AMBER imagines printing interactive
smart food and drug labels, or using them in next-generation banknote security
and e-passports.

The future is arriving fast.