AsianScientist (Nov. 21, 2017) – Inspired by the eyes of nocturnal animals, scientists in South Korea have developed an electroluminescent film that is four times brighter than existing variants. Their findings are published in Advanced Materials Technologies.
Electroluminescence refers to an optical and electrical phenomenon in which a material emits light in response to the passage of an electric current. Electroluminescent films made from phosphor powder have excellent durability in a deformed state due to their flexibility and elasticity. They are also power-efficient and inexpensive to produce. However, their low brightness have hampered their practical application in devices.
In this study, a team of researchers led by Dr. Choi Byeong-dae at the Daegu Gyeongbuk Institute of Science and Technology (DGIST) mimicked the retroreflection characteristics—the light returns to the light source without being dispersed—of the eyes of nocturnal animals to design an electroluminescent film that can improve the luminance of devices.
They fabricated an electroluminescent film consisting of a light-transmitting luminescent film on a retroreflective electrode and achieved a wide viewing angle of reflected light on the prismatic retroreflective electrode surface.
In addition, the team discovered that when the light source had a high transmittance, there is no loss of reflected light, and by controlling the concentration of luminescent particles and blending luminescent particle-polymer binder complexes at specific ratios, they were able to develop a film that improved brightness by 442 percent (1017 candela/m2, 6.67 volts/μm at 10 kilohertz) compared to conventional technology.
“This study is significant as it has applied the light reflection principle of nocturnal animal eyes, which have high light utilization efficiency, to light emitting devices,” said Choi.
“Since this technology can also be applied to self-luminous displays, it is expected to contribute to the strengthening of Korea’s competitiveness in the global lighting market, which is estimated to reach more than 120 trillion won per year in the future. It will also be useful for developments in the next-generation display market,” he added.
The article can be found at: Shim et al. (2017) Highly Bright Flexible Electroluminescent Devices with Retroreflective Electrodes.
Source: Daegu Gyeongbuk Institute of Science and Technology; Photo: Pixabay.
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