A new breakthrough from researchers in Singapore could bring bright, flexible and low-power displays to applications ranging from wearable health monitors to underwater communication.
Imagine a small skin patch that changes color when your blood sugar level becomes abnormal, a flexible display wrapped around a diver's arm that remains readable underwater, or a soft robot that uses glowing signals to communicate when it touches an object or detects damage.
These technologies require displays that are thin, flexible, energy-efficient and durable. Yet existing display technologies often struggle to deliver all of these properties at the same time.
Researchers at the National University of Singapore (NUS), working with scientists from the Institute of Materials Research and Engineering (IMRE) and the Institute of High Performance Computing (IHPC) under Singapore's Agency for Science, Technology and Research (A*STAR), have now developed a much brighter and more durable type of electrochemiluminescent display.
Their new design reaches a brightness of 1,552 candelas per square metre (cd/m²)—roughly three to four times brighter than a typical smartphone screen used indoors and 3.2 times brighter than the best conventional electrochemiluminescent devices.
The study was published in Science Advances.
What Is Electrochemiluminescence?
The technology behind the breakthrough is called electrochemiluminescence (ECL).
ECL can be thought of as an artificial cousin of bioluminescence—the natural light produced by organisms such as fireflies and some deep-sea animals. However, instead of biological processes producing the glow, electricity triggers a chemical reaction that generates light.
A typical ECL device contains a light-emitting molecule dissolved in a liquid electrolyte. This liquid is placed between two electrodes. When alternating electrical current is applied, the molecules repeatedly gain and lose electrons. These reactions eventually release energy in the form of photons, producing visible light.
One major advantage of ECL is its relatively simple structure. Unlike organic light-emitting diodes (OLEDs), which require multiple carefully engineered layers, ECL devices can be made using a liquid light-emitting layer between electrodes.
This makes them naturally suited to thin and flexible electronics.
However, ECL technology has had a serious weakness: brightness and stability.
Conventional ECL devices have generally been too dim for practical displays and often produce light only for a short period. This has limited their use largely to laboratory demonstrations.
The NUS-led team set out to solve both problems.
A New Liquid Makes the Difference
The researchers discovered that one of the biggest limitations came from the electrolyte, the liquid responsible for carrying charged particles through the device.
Traditional ECL systems commonly use a type of ionic liquid. Ionic liquids are salts that remain liquid at room temperature and are useful in many electrochemical technologies.
But the ions in conventional liquids can be relatively large and bulky. Their movement can slow down charge transfer and reduce the efficiency of the light-producing reaction.
The researchers replaced the conventional electrolyte with an ionic liquid containing a smaller and more mobile negative ion.
This seemingly simple material change produced a major improvement.
The two ions within the new electrolyte play different roles. The smaller negative ion helps electrons move more efficiently at the electrode surface while also improving chemical stability. At the same time, the positive ion allows more of the light-emitting dye to dissolve in the liquid.
In simple terms, the new liquid allows the device to have both faster chemical reactions and more light-emitting material available to produce light.
Together, these effects dramatically increased the brightness and lifetime of the device.
Redesigning the Electrodes
Changing the electrolyte was only part of the solution.
The team also redesigned the physical structure of the ECL device.
Instead of using two identical transparent electrodes, the researchers used different electrodes optimized for different jobs.
One electrode was textured to encourage the chemical reactions responsible for producing light. The other was smoother and designed to allow light to pass through efficiently.
The researchers also added a thin silver mirror behind the rear electrode.
This mirror reflects light that would otherwise escape backward, directing more of it toward the viewer.
The combination of improved materials and smarter device architecture produced the record brightness.
More importantly, the new devices were significantly more durable.
During repeated on-and-off testing, the new ECL devices maintained brightness up to 82 times higher than conventional versions after 10 cycles.
During continuous operation, they produced light for approximately two hours, compared with only about 29 minutes for the older design.
This represents an important step toward moving ECL technology beyond short laboratory demonstrations.
From Smart Skin Patches to Underwater Displays
To show what the improved technology could actually do, the researchers developed several working prototypes.
One was a flexible skin patch designed to work alongside a sweat-based glucose sensor.
The patch used blue and red light to communicate different glucose readings. Instead of requiring a person to look at a separate electronic screen, the wearable patch itself could provide a simple visual indication.
Such an approach could eventually make health-monitoring devices more convenient and easier to interpret.
The researchers also created a seven-segment digital display, similar to the numbers found on digital clocks.
The display successfully showed numbers from 1 to 9 and switched between them repeatedly. This demonstrates that the technology can potentially be used for changing information rather than simply producing a static glow.
Future applications could include smart packaging, environmental sensors, industrial equipment and soft robots.
Perhaps the most striking demonstration was a flexible solid-state ECL device that continued glowing while completely submerged in water.
This property could open opportunities for underwater displays and signaling systems, where conventional electronic interfaces can face significant challenges.
Potential applications include underwater monitoring, communication and visual interfaces for divers or aquatic robots.
Why This Breakthrough Matters
The researchers envision ECL technology becoming a kind of soft visual layer that can conform to the surface of an object, rather than requiring a rigid screen.
For wearable electronics, this could mean displays that bend naturally with the human body.
For soft robotics, ECL could allow a robot to visually communicate information through its own skin. For example, a robot could change its glowing pattern when it senses touch, movement or structural damage.
Because ECL devices can be thin, flexible and relatively energy-efficient, they could also be useful where conventional displays are too rigid, complicated or power-hungry.
The ability to operate from a small battery is particularly important for wearable applications.
The Road Ahead
Despite the breakthrough, the technology still has challenges to overcome.
The researchers found that red light remains the strongest emission, while other colors such as blue and green need further improvement.
Their next goal is therefore to develop brighter and more stable multicolor ECL displays. This will require improvements in both the light-emitting molecules and the electrolytes, along with further optimization of the device structure.
The team is also working toward stretchable and self-healing ECL devices.
Such devices could continue working when stretched or bent and potentially recover their light-emitting capability after being damaged. This would make them particularly attractive for wearable electronics, soft robots and underwater systems.
Ultimately, the goal is to transform ECL from a laboratory phenomenon into a practical technology for soft, flexible and low-power visual communication.
If successful, future displays may no longer need to look like traditional rigid screens. Instead, they could become part of our clothing, skin-mounted sensors, robotic surfaces and even underwater equipment—quietly glowing wherever information needs to be seen.
Reference:
- Meilin Liu et al.
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