Imagine a monitor that can charge itself when you’re not using it. Instead of just standing idle, it can collect light from its surroundings and turn it into electricity.
A new study shows that this idea is not only possible – it is already working in the laboratory.
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Researchers have created a special device that can function both as a solar cell and as a light-emitting diode (LED), and which does both jobs very efficiently. The study, published in the journal Joule, describes a device that converts sunlight into electricity with an efficiency of 26.7 percent, and at the same time emits light with an efficiency of about 31 percent.
These are impressive numbers, even for devices that are only designed to do one of these tasks.
The key material behind the breakthrough
The key material behind this breakthrough is something called metal-halide perovskites. These materials have become very popular in recent years because they are relatively cheap to produce, and because they can be adapted to absorb or emit different types of light.
Until now, however, researchers have usually designed perovskite solar cells and LEDs separately, because they require very different structures.
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The challenge of thickness
The main challenge is about thickness. For an LED to work well, the perovskite layer must be very thin so that the light can escape easily. However, for a solar cell to work well, the layer must be much thicker to absorb enough sunlight. This difference has made it difficult to combine both functions into a single device without losing efficiency.
Smart solution with sponge structure
The new study, led by researchers from the University of Colorado Boulder and the University of Science and Technology of China, found a clever way to solve this problem. Instead of choosing between thin or thick, they redesigned the way light travels inside the device.
Their solution consists of adding tiny sponge-like structures made of aluminum oxide inside the perovskite layer. These structures are far too small to be seen, but play a major role. They help to conduct light more efficiently – both when the device absorbs light and when it emits it. At the same time, they allow electricity to flow smoothly through the device, which is essential for good performance.
Heals the defects in the material
Another important improvement is the reduction of tiny defects in the material. Normally, these defects capture light and turn it into heat, which wastes energy. The new design uses special surface treatments to “heal” these defects. This allows the light to bounce around inside the material and have a second chance to escape – a process called photon recycling. The result is that the device becomes even more efficient.
Lasts longer – and performs better
Tests showed that the new device not only performs well in both modes, but also lasts longer. It retained most of its performance even after prolonged use, which is very important for real-world applications.
New opportunities for the screens of the future
This type of two-function device can open up completely new possibilities. For example, the screens of the future can harvest ambient light to extend battery life, and lighting systems can recover energy when turned off. More generally, the research shows that combining light absorption and light emission in one device is not just a theory – it is a practical engineering solution.
By carefully designing both the structure and the material, researchers are constantly finding new ways to create devices that are smarter, more efficient, and more versatile than ever before.
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