Scientists have engineered a novel type of light-emitting diode display, known as OLED, capable of dynamically altering the shape of its light beam. This innovative technology stacks two OLED units vertically, allowing for independent control and emission. Unlike typical OLEDs with a uniform light projection, this new device can switch between a focused spot of light and a ring-shaped beam, or even create customized emission patterns.
The device achieves this beam shaping by employing a unique driving system and a specially designed optical structure. By using alternating current and pulse width modulation, the two OLED units can be controlled with just two electrodes, simplifying the device architecture. The key to the beam shaping lies in the precise engineering of the internal layers of the OLED, creating what’s known as a microcavity. This microcavity is tailored to direct light emission in specific directions. One unit is designed for forward emission, projecting light straight ahead, while the other is optimized for sideward emission, creating the ring shape.
Researchers demonstrated that by combining the emissions from both units, they can create a variety of beam shapes. Measurements confirmed a clear separation between the forward and sideward emission patterns, with the sideward emitting unit showing maximum intensity at an angle of 56 degrees. The technology boasts a rapid switching speed, capable of changing beam shapes in microseconds, making it suitable for high-speed applications.
To ensure consistent color output across different beam shapes, the researchers employed different light-emitting materials for each OLED unit, compensating for inherent spectral shifts caused by the optical design. The versatility of the design was further validated by simulations showing its compatibility with various light-emitting materials, including quantum dots and perovskites, suggesting broad applicability across different display types.
Furthermore, the team explored the use of simple external optical elements like lenses and prisms to further refine the beam shaping capabilities. Adding a half-sphere lens enhanced the contrast and focus of the light beam, while a prism allowed for the creation of asymmetric light patterns, demonstrating the potential for tailoring the light output for specific applications.
This advancement in OLED technology opens up possibilities for advanced display systems with adaptable light projection, which could be beneficial in various fields requiring controlled illumination, such as specialized lighting, advanced imaging, and next-generation display technologies.
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