The information encoded in circularly polarized (CP) light could help future technologies for display, sensing, communications, and quantum applications deliver on their promise of greater efficiency and security. OLEDs can be engineered to emit either left- or right-handed CP light. Typically, however, the handedness of the CP light is controlled by choosing a specific, mirror-image form of the light-emitting molecule within the OLED device. To switch handedness, access to both mirror image forms of the chiral molecule — left-hand and right-hand — is required. A University of Oxford team simplified this process by developing a design for an OLED that electrically flips the handedness of CP light without changing the device’s light-emitting molecules. Instead, specific interlayers in the OLED device are used to switch between left- and right-handed CP emission. Researchers discovered a way to electrically switch OLEDs to emit either left- or right-handed circularly polarized (CP) light without changing the light-emitting molecules. The handedness of the emitted CP electroluminescence (CP-EL) is controlled by using specific interlayers in the OLED device, with no change in the emissive material composition or thickness. Courtesy of the University of Oxford. This approach provides a way to access OLEDs with high levels of circularly polarized electroluminescence (CP-EL) from a single emissive enantiomer. It enables access to both left- and right-handed CP-EL from the same enantiomer material, in the same device architecture, making it simpler and less expensive to direct and control the polarization of light in OLEDs. The researchers control the CP-EL handedness of a chiral OLED electrically, without changing the handedness or composition of the active layer, by tuning the charge carrier mobility and the recombination zone position. Depending on whether charge transport is balanced or unbalanced, the OLED device produces one, or the other, mirror form of CP light. The charge injection and charge balance are controlled using the interlayers of the OLED device and are enabled using a newly developed chiral additive, with very high chiroptical activity, that has specific effects on CP light. CP-OLED device technologies that provide a simple, relatively low-cost way to control left- and right-handedness in CP light could enable more energy-efficient displays, more secure encrypted communications, and high-performance quantum information systems. “Adding circular polarization allows for additional information to be encoded into the light signal,” professor Matthew Fuchter said. “Rather than your signal being simply on or off, it could additionally be on-and-left or on-and-right.” To the best of the team’s knowledge, electrical control of CP-EL has previously been observed in inorganic materials only, and in different device configurations (specifically, in light-emitting transistors). As such, the team’s findings could enable new directions and advancements in CP-OLED device technologies with controllable spin angular momentum. Previous methods of controlling CP light in OLEDs required differently handed forms of the same molecule to be separated — a laborious, expensive process that is difficult to scale. The new approach to controlling CP light in OLEDs could, in the team’s view, represent a paradigm shift in the way that CP-OLEDs are created and used. The study shows links between molecule chirality and light chirality that may contribute to the ongoing study of the role that physics plays in chiral optoelectronic systems. The team hopes that its insights into the physics of chiral organic materials will help open the path to advanced displays, secure communication systems, and future quantum technologies. The research was published in Nature Photonics (www.doi.org/10.1038/s41566-025-01780-4).