Quantum Dot Film Can Withstand High Temperatures and Humidity
The joint KAIST research team of Professor Byeong-Soo
Bae of the Department of Materials Science and Engineering and Professor Doh
Chang Lee of the Department of Chemical and Biomolecular Engineering was
able to fabricate a siloxane-encapsulated quantum dot film, which exhibits
stable emission intensity over one month even at high temperatures and
of this study were published in the Journal
of the American Chemical Society (JACS) on November 29, 2016. The research
article is entitled “Quantum Dot/Siloxane Composite Film Exceptionally Stable
against Oxidation under Heat and Moisture.” (DOI: 10.1021/jacs.6b10681)
dots (QDs), light-emitting diodes (LEDs) for
next-generation displays, are tiny particles or nanocrystals of semiconducting materials. Their
emission wavelength can easily be adjusted by changing their sizes, which are
just a few nanometers. A wide spectrum of their colors can also achieve
ultra-high definition displays.
Due to these characteristics, QDs
are coated on a film as a polymer resin in dispersed form, or they are spread
on an LED light source. They are thus considered to be crucial for next
their exceptional optical properties, however, QDs are easily oxidized in a high
temperature and high humidity environment, and, as a result, this greatly
deteriorates their luminescence quality (quantum efficiency). Therefore, they are
encapsulated in an extra thin layer to block oxygen and moisture.
in the current market have a film inserted to separate them from LEDs, which
create heat. The high unit cost of this protective layer, however, increases
the overall cost of displays, lowering their price competitiveness in the
For a solution, the research team applied the sol-gel condensation
reaction of silane precursors with QDs. This technology uses the
reactions of chemical substances to synthesize ceramics or glass at a low
applied QDs in a heat resistant siloxane polymer by employing this technology.
The siloxane resin acted as a cup holding the QDs and also blocked heat and
moisture. Thus, their performance can be maintained without an extra protective
evenly dispersed into the resin from a chemical process to fabricate a QD
embedded film and retained the high quality luminescence not only at a high
temperature of 85°C and in a high humidity of 85%, but also in a high acid and
high base environment. Remarkably though, the luminescence actually increased
in the high humidity environment.
technology is used, the overall price of displays will decrease by producing a
stable QD film without an extra protective barrier. In the future, the QD film
can be directly applied to a blue LED light source. As a result, it will be possible to develop a QD display
that can reduce the amount of QDs needed and improve its performance.
Bae said, “We have proposed a way to make quantum dots overcome their
limitations and have wide applications as they are being developed for next-generation
displays. Our technology will make significant contributions to the display
industry in the country.”
He also added, “In the future, we plan to cooperate with
companies both in and out of the country to improve the performance of quantum
dots and concentrate on their commercialization.”
team is currently applying for related patents both in and out of the country.
The team is also planning to transfer the patents to Sol Ip Technology Inc., a
company founded at KAIST, to start the commercialization.
quantum dot (QD) films showing performance stability in boiling water
2 and 3:
condensation reaction in silane precursors between Methacryloxypropyltrimethoxysilane
(MPTS) and diphenylsilanediol (DPSD). The inset shows photographs of a QD-oligosiloxane
resin under room light (left) and a UV lamp (λ = 365 nm) (right).
addition reactions among carbon double bonds of methacryl functional groups and
oleic acids. The inset shows photographs of a QD-silox film under room light
(left) and a UV lamp (λ = 365 nm) (right).
qd-silox film fabrication process.jpg