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Scientists Discover Way to Send Information into Black Holes Without Using Energy

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This Color-Changing Screen Doesn’t Heat Up, It Actually Gets Cooler To Cool Your Buildings, Displays. Here’s How

Electronic displays are everywhere. From neon shop signs and glowing billboards to the route indicators on buses, digital displays have become a normal part of modern life. But behind their bright visuals lies a big problem — these devices generate heat. Every color change or illuminated pattern often adds to the temperature of the surface beneath them. Multiply this by the millions of signs across cities, and the energy impact becomes significant.

Now, a breakthrough innovation reported in ACS Energy Letters may change how the world thinks about displays forever. A team of researchers — including Boxiang Wang, Ming Xiao and Shenghao Jin — has developed a flexible, color-changing display that cools surfaces instead of heating them. Even more remarkably, it needs no active cooling, no fans, and very little electricity, making it an exciting candidate for sustainable advertising, smart buildings, vehicles, and even wearable technology.

This technology represents a new class of self-cooling, programmable displays that work through a powerful mechanism known as passive radiative cooling — but with a twist: it can change color dynamically, something traditional cooling materials can't do.

Why Cooling Displays Matter: Understanding the Need

As the world warms and cities experience record-breaking heat waves, the demand for cooling systems is skyrocketing. Air conditioners, fans, and refrigeration units consume massive amounts of power. According to international energy estimates, cooling already accounts for a large share of electricity use, especially in tropical and sub-tropical regions. As climate change intensifies, this demand will only rise.

At the same time, modern cities are filled with heat-emitting devices:

  • LED billboards

  • Neon lights

  • Traffic displays

  • Digital menus

  • Public transport signs

  • Smart building surfaces

Individually, each device generates only a small amount of heat. Collectively, especially in dense cities, they contribute to the urban heat island effect, making streets hotter, increasing energy usage, and placing more pressure on cooling infrastructure.

If displays could cool themselves, and even cool the surfaces they cover, the impact would be enormous. That is precisely where the new innovation shines.

Existing Cooling Materials Have a Major Limitation

Scientists have been studying passive daytime radiative cooling (PDRC) for years. These are materials that stay cool under sunlight without using electricity. They do this by:

  • Reflecting most of the sunlight

  • Emitting heat as infrared radiation back into space

Such materials can reduce surface temperatures by several degrees even under harsh sunlight. However, they have a major limitation:

They can’t change colors.

Most PDRC materials are white or silver. They cannot display text, images, advertisements, or patterns. This makes them useless for applications like electronic signs or dynamic displays.

On the other hand, color-changing displays (like electrochromic or LED-based devices) tend to absorb light, especially when showing darker or vibrant colors. That absorption turns into heat, raising the device's temperature — the very problem researchers want to avoid.

The challenge, therefore, has been clear:

✔ Create a material that cools like PDRC
✔ But can also change colors dynamically
✔ While consuming little energy
✔ And without generating heat during switching

This new study solves exactly that.

A Self-Cooling Display: The Science Behind the Innovation

The researchers developed a multilayered display system using:

  • A specially engineered electrode

  • An indium tin oxide glass counter electrode

  • An electrolyte solution containing silver ions

The magic happens when voltage is applied.

When the display shows white

  • The top layer reflects sunlight, just like effective cooling materials.

  • The device cools itself and the surface beneath it, reducing temperatures by 3 to 5°C (5 to 10°F).

When the display shows color

  • The applied voltage causes silver to deposit onto the lower glass layer.

  • This selectively absorbs only narrow wavelengths of light.

  • That means the device can produce vivid colors like magenta without heating up.

  • Light reflection remains strong, maintaining cooling performance.

This controlled absorption is the core breakthrough. Unlike conventional displays, this device only absorbs the wavelengths it needs to show the color, avoiding excess heat.

And yes — the process is reversible.

Colors can be switched repeatedly with minimal energy consumption.

Flexibility: A Game-Changing Feature

The research team did not stop at performance testing. They also attached the display to flexible plastic sheets and wrapped it around a human arm.

The display maintained:

  • Cooling performance

  • Color-changing capability

  • Mechanical flexibility

  • Visibility in indoor and outdoor light

This opens the door to wearable cooling displays, a futuristic concept where your clothes, accessories, or even skin patches could show information while keeping you cool.

Imagine:

  • A flexible fitness tracker that doesn’t heat your skin

  • A medical patch that displays changing health information

  • Wearable billboards for outdoor workers

  • Smart uniforms for firefighters or construction teams

The possibilities are wide-ranging.

How Much Cooler Is This Display Compared to Others?

During outdoor tests in summer heat, the new display outperformed traditional technologies dramatically.

Cooling Performance

Compared to conventional outdoor display devices, the new technology cooled its surface by an additional:

6 to 13°C (11 to 23°F)

while still showing bright, dynamic colors.

No existing display device offers such a combination of:

  • Color-changing capability

  • Energy efficiency

  • Radiative cooling

  • Flexibility

This makes it one of the most promising candidates for next-generation smart signage and sustainable building design.

Turning Pixels Into Letters: The Multi-Pixel Demonstration

To prove practical usability, the scientists created a pixelated electrode. Each pixel was separated and filled with its own pocket of electrolyte.

By applying different voltages to each pixel, they could:

  • Control colors independently

  • Form letters and symbols

  • Display content indoors and outdoors

This means the technology can be scaled into full displays capable of:

  • Advertisements

  • Information boards

  • Animated signs

  • Building façades

  • Vehicle displays

Unlike LED screens, it would remain cool even when showing bright or dark colors.

Where Could This Technology Be Used?

The display’s unique features — flexible design, low-energy operation, passive cooling, and dynamic color — make it suitable for a huge range of future applications.

1. Smart Building Surfaces

Imagine a skyscraper wrapped in a billboard that:

  • Displays ads

  • Reflects sunlight

  • Cools the building

  • Cuts AC usage

Cities could transform their building exteriors into cooling, energy-saving media surfaces.

2. Outdoor Advertising

Billboards in sunny climates often overheat. This display:

  • Uses less energy

  • Reduces heat impact

  • Shows vivid colors

  • Lasts longer due to decreased thermal stress

Companies could drastically reduce the cost of powering and cooling their signage.

3. Wearable Devices

Fitness bands, skin patches, medical wearables, and smart clothing could all stay cool while displaying information.

4. Vehicles

Car roofs, smart dashboards, and even truck advertisements could use this device for safer, cooler display surfaces.

5. Smart Consumer Products

From backpacks to e-readers, cooling displays could become part of everyday objects.

6. Emergency and Military Equipment

In harsh environments, where heat buildup can endanger users, such cooling displays could be invaluable.

Why This Breakthrough Matters for Sustainability

This technology arrives at a crucial moment. Climate models show that global temperatures will continue rising, pushing countries to rethink how they manage energy consumption.

Cooling is one of the largest and fastest-growing energy demands worldwide. Innovations that reduce heat without consuming electricity are now essential.

This new display:

  • Reduces energy demand for cooling

  • Prevents heat buildup in devices and buildings

  • Works with minimal power

  • Contributes to reducing urban heat islands

  • Supports sustainable, eco-friendly digital infrastructure

As cities grow smarter, greener, and more connected, such technologies will play a key role in balancing digital progress with environmental responsibility.

The Road Ahead: Challenges and Future Potential

While the proof-of-concept device is promising, several steps remain before mass adoption:

  1. Scaling production to large display sizes

  2. Enhancing durability against outdoor conditions

  3. Expanding the color range and improving resolution

  4. Reducing costs for commercial manufacturing

  5. Integrating with existing display control systems

However, given the performance shown in early tests, the future is extremely promising.

In the next decade, we may see:

  • Entire building façades wrapped in cooling digital skins

  • Roadside signs that never heat up

  • Wearable gadgets that stay comfortable on skin

  • Smart vehicles that show messages while reflecting sunlight

  • Sustainable cities using cooling tech to reduce energy consumption

This innovation could be one of the key stepping stones toward low-energy, climate-resilient digital displays around the world.

Conclusion: The Dawn of Self-Cooling, Flexible Digital Displays

The development of a flexible, dynamic display that cools itself instead of heating up is a significant milestone in science and technology. Combining color programmability with passive radiative cooling was once thought nearly impossible. Yet, the researchers behind this study have demonstrated that it can be achieved with clever engineering and deep understanding of material behavior.

Their device:

  • Shows clear, bright colors

  • Reduces surface temperature dramatically

  • Uses very little electricity

  • Works while bent, flexed, or wrapped

  • Opens up new possibilities for buildings, wearables, vehicles, and public displays

In a warming world, such innovations are no longer optional — they are essential. As technology continues to evolve, the line between energy-saving materials and smart electronics will blur, giving rise to devices that are both functional and environmentally responsible.

The next time you walk past a billboard or glance at a wearable device, it may not just display information — it may also be helping to cool the world around you.

Reference: Shenghao Jin, Fan Yi, Zhen Gong, Dong Yang, Yujie Peng, Jiahao Hou, Jingjing Mao, Junkai Wang, Mengqi Liu, Run Hu, Kaihuan Zhang, Changying Zhao, Ming Xiao, and Boxiang Wang, "Daytime Radiative Cooling with Electrochemically Driven Dynamic Colors", ACS Energy Letters 0, 10. DOI: 10.1021/acsenergylett.5c02196

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