Imagine a screen that can power itself when you are not using it.
Instead of just sitting idle, it could collect light from its surroundings and turn that light into electricity.
A new study shows this idea is not just possible, but already working in the lab.
Researchers have created a special device that can act both as a solar cell and as a light-emitting diode (LED), doing both jobs very efficiently.
The study, published in Joule, reports a device that converts sunlight into electricity with an efficiency of 26.7% and also emits light with an efficiency of about 31%.
These numbers are impressive even for devices designed to do only one of these tasks.
The key material behind this breakthrough is called metal-halide perovskites. These materials have become popular in recent years because they are relatively cheap to make and can be tuned to absorb or emit different kinds of light.
However, until now, scientists have usually designed perovskite solar cells and LEDs separately because they require very different structures.
The main challenge comes down to thickness. To work well as an LED, the perovskite layer needs to be very thin so light can easily escape.
But for a solar cell, the layer must be much thicker to absorb enough sunlight. This difference has made it difficult to combine both functions in a single device without losing efficiency.
The new study, led by researchers from 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 how light moves inside the device.
Their solution involves adding tiny sponge-like structures made of aluminum oxide inside the perovskite layer. These structures are far too small to see but play a big role. They help guide light more effectively, both when the device is absorbing light and when it is emitting it. At the same time, they allow electricity to flow smoothly through the device, which is essential for good performance.
Another important improvement is reducing tiny defects in the material. Normally, these defects trap light and turn it into heat, wasting energy. The new design uses special surface treatments to “heal” these defects. This allows light to bounce around inside the material and get another chance to escape, a process known as photon recycling. As a result, the device becomes even more efficient.
Tests showed that the new device not only performs well in both modes but also lasts longer. It kept most of its performance even after long periods of use, which is important for real-world applications.
This kind of dual-function device could open up new possibilities. For example, future displays could harvest ambient light to extend battery life, and lighting systems could recover energy when turned off. More broadly, the research shows that combining light absorption and emission in one device is not just a theory, but a practical engineering solution.
By carefully designing both the structure and the material, scientists are finding new ways to make devices that are smarter, more efficient, and more versatile than ever before.
