- The new technique can make OLED displays brighter, with better contrast and longer life.
- It involves altering the chemistry of OLED materials in such a way that it produces unique polarized light that can bypass the screen’s anti-glare filter.
Modern screens of smartphones, tablets, laptops, and televisions are lit by tiny devices called organic light-emitting diodes (OLEDs). These diodes consist of a layer of organic compound that emits light in response to an electric current.
To make these screens clearly visible on a bright sunny day, they are covered with an anti-glare filter. Due to the filtering mechanics of anti-glare filters, about 50 percent of the light produced by each OLED pixel remains trapped inside the screen, reducing the energy efficiency of the diode by half.
To increase usability — digital display wouldn’t be popular if they could not be used outside — OLED manufacturers compromise with the energy efficiency of the device. Now researchers at Imperial College London have developed a new method that can make OLED displays brighter, with better contrast and longer life.
The new method involves altering the chemistry of OLED materials in such a way that it generates unique polarized light that can bypass the anti-glare filter. Screens made of such materials would be more energy-efficient and have a lower carbon footprint.
Controlling dissymmetry of circularly polarized light could revolutionize the electronic device displays. One of the emerging techniques to induce circularly polarized electroluminescence from the active layer of OLEDs involves blending achiral polymers with chiral molecule additives. In this case, the sign of the circularly polarized light is controlled by the molecule’s absolute stereochemistry.
Reference: ACS Nano | DOI:10.1021/acsnano.9b02940 | Imperial College London
Researchers carefully analyzed such systems and demonstrated that it’s possible to obtain both brightness and efficient circularly polarized polymer light-emitting diodes.
Microscopic image of chiral layers of carbon-based polymers for LEDs | Source: Imperial College London
The brightness and efficiency are achieved due to an interplay between circularly polarized light amplification or inversion through a chiral medium and localized circularly polarized emission originating from molecular chirality.
They linked electronic, spectroscopic, and morphological characterization in thin layers with theoretical studies to provide insights into the mechanisms that lead to circularly polarized luminescence and high-performance OLEDs.
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Other Applications
Although the study was primarily focused on OLED displays, researchers soon noticed that their method could also be used in other applications. The polarized light produced by the new material can be used in data storage, environmental monitoring, optical quantum computation, encryption and transmission of information, and biosensing.
