Flexible electronics get brighter
A luminescent material shines brighter by simultaneously stretching it
and applying an electric field

Date:
April 22, 2022
Source:
DGIST (Daegu Gyeongbuk Institute of Science and Technology)
Summary:
Scientists have fabricated a flexible material that lights
up brightly when stretched and/or when an electric field
is applied. The results show promise for the development of
bright, sustainable, stretchable devices for use, for example,
as interactive skin displays and in soft robotics.



FULL STORY ========================================================================== Scientists at Daegu Gyeongbuk Institute of Science and Technology (DGIST)
in Korea have fabricated a flexible material that lights up brightly
when stretched and/or when an electric field is applied. The results
were published in the journal Applied Physics Reviews and show promise
for the development of bright, sustainable, stretchable devices for use,
for example, as interactive skin displays and in soft robotics.


==========================================================================
"Our material overcomes challenges in 'alternating-current-driven electroluminescent' (ACEL) devices that are currently under
development," explains Soon Moon Jeong of DGIST's Division of Energy Technology. "Current devices don't offer as much luminescence as
scientists are aiming for due to issues with their design." Soft, light-emitting ACEL devices are made by sandwiching a light-emitting
compound between two electrode layers. But for the light in the middle
to reach the surface and actually be seen, it needs at least one of the electrode layers to be transparent. This, however, leads to several
issues depending on the type of material used, such as the electrode
being brittle or difficult to fabricate.

Jeong and his colleagues overcame this and other design issues in ACEL
devices by inserting stretchable silver nanowire electrodes in-parallel
in between two light-emitting layers made of copper-ion-doped zinc sulfide particles embedded in polydimethylsiloxane (ZnS:Cu/PDMS). ZnS:Cu/PDMS has
an attractive property: it generates light when it is deformed. This is
called mechanoluminescence. By adding the silver nanowire electrodes,
the device also becomes electroluminescent. In other words, applying
an electric field to it causes the material to shine brightly. "Our
device is unique in that it can simultaneously produce mechano- and electroluminescence," says Jeong.

The design also allows the use of thick light-emitting layers in contrast
to previous ACEL devices that can only use layers that are thin enough to
apply a strong electric field between the two electrodes. The new design overcomes this issue by inserting the electrodes as ultra-thin wires
inside of the light- emitting material. The thicker material produces
3.8 times as much electroluminescent brightness as other ACEL devices.

"Our proposed structure could currently be used in large-scale outdoor billboards or light-emitting banners, due to its sturdiness against environmental factors and its simple design," says Jeong.

The team next wants to improve the device's electroluminescence in
response to a low electric field. To achieve this, they plan to arrange
the silver nanowires in diverse directions, instead of in-parallel as
with the current device.


========================================================================== Story Source: Materials provided by DGIST_(Daegu_Gyeongbuk_Institute_of_Science_and Technology). Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Seongkyu Song, Hyeon-Seo Choi, Chang-Hee Cho, Sang Kyoo Lim,
Soon Moon
Jeong. Bright and uniform light emission from stretchable,
dual-channel energy conversion systems: Simultaneous harnessing
of electrical and mechanical excitations. Applied Physics Reviews,
2022; 9 (1): 011423 DOI: 10.1063/5.0080090 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220422094323.htm

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