In a breakthrough that could transform future screens and communication technology, researchers at the University of Oxford have developed a way to make OLEDs (organic light-emitting diodes) switch the direction of light’s “twist” using only an electrical signal.
For the first time, an OLED can emit either left-handed or right-handed circularly polarized light without needing to change the light-producing molecules inside the device.
The discovery, published in the journal Nature Photonics, opens the door to more energy-efficient displays and new ways of sending and storing information using light.
Light can be “circularly polarized,” meaning it rotates as it moves, either clockwise or counterclockwise.
This is sometimes described as having a left-handed or right-handed twist. Until now, the only way to control which type of circularly polarized light an OLED produced was to use a specific “mirror image” version of a molecule.
These mirror-image molecules, known as chiral molecules, behave like left-handed and right-handed corkscrews.
Producing both forms of these special molecules is complicated, costly, and difficult to scale up. That has been a major obstacle for creating practical and affordable polarized OLEDs.
The Oxford team found a way around this problem. They discovered that they could use just one version of the molecule and still produce both left- and right-handed light.
Instead of changing the molecule, they changed the way electrical charges move and combine inside the OLED.
By controlling whether the flow of positive and negative charges is balanced or unbalanced, they were able to switch the light’s handedness.
This effect is made possible by a special polymer material in the device. The polymer naturally forms a tightly twisted structure, like a spring.
This unique arrangement affects how light is emitted and allows the same material to create two different types of circularly polarized light, simply by adjusting the electrical conditions.
According to Professor Matthew Fuchter, the lead author of the study, this ability to switch polarization adds a new layer of information to light. Instead of light being just “on” or “off,” it can now be “on and left” or “on and right.” This extra level of control could be extremely useful in future technologies.
Circularly polarized light is important for advanced displays, such as augmented and virtual reality screens, because it can improve efficiency and image quality. It also has potential uses in secure communication, where information can be encoded more safely, and in quantum technologies, where subtle properties of light are critical.
This new approach marks a major shift in how scientists understand the relationship between the structure of molecules and the behavior of light. It also makes circularly polarized OLEDs much more practical to manufacture on a large scale.
The researchers hope their discovery will lead to faster progress in next-generation displays, safer communication systems, and powerful new technologies that rely on precise control of light.
Source: University of Oxford.
