New Material For Low Cost Polymer LEDs And Solar Cells
Korean researchers have developed a new plasmonic material for low cost polymer light-emitting diode and polymer solar cell applications.
Asian Scientist (Jul. 24, 2013) - Korean researchers have developed a new plasmonic material for low cost polymer light-emitting diode (PLED) and polymer solar cell (PSC) applications. The new material, synthesized through a simple and cheap process, offers significantly enhanced performance over materials currently used in optoelectronic devices (OEDs).
Most semiconducting OEDs, including photodiodes, solar cells, light emitting diodes (LEDs), and semiconductor lasers, are based on inorganic materials. Examples include gallium nitride for light-emitting diodes and silicon for solar cells.
The cost of OED fabrication had been increasing because of a shortage of raw materials, and the complex processing required to manufacture OEDs from inorganic materials. Therefore, there is great interest in developing thin-film OEDs made from alternative semiconductors.
Organic semiconductors, in particular, are the focus of much research because they have the potential for low-cost and large-area fabrication. However, further improvements in efficiency are needed, before there can be widespread use and commercialization of these technologies.
The use of plasmonic materials in organic materials has been shown to improve the performance of organic OEDs. Plasmonics is a branch of physics that deals with light and matter interacting in specific ways, as plasmonic materials are able to couple photons and electrons to form plasmons.
Now, researchers from Ulsan National Institute of Science and Technology (UNIST), Korea, have prepared carbon-dot-supported silver nanoparticles (CD-Ag NPs) as a new plasmonic material. Carbon dots consist of carbon, hydrogen, and oxygen with a quasi-spherical structure in which the carbon shows the character of crystalline graphite.
The material is easy to synthesize with basic equipment and can be processed as a low-temperature solution. This low-temperature solution processability enables roll-to-roll mass production techniques and is suitable for printed electronic devices.
In their paper, published in Nature Photonics, the UNIST researchers demonstrated that using CD-Ag NPs in fluorescent PLEDs and PSCs resulted in significant improvements in performance for both types of OEDs.
The PLEDs achieved a remarkably high current efficiency and luminous efficiency (LE) while PSCs produced in this way showed enhanced power conversion efficiency (PCE) and internal quantum efficiency (IQE).
The LE and IQE are among the highest values reported to date in PLEDs and PSCs, respectively.
"The material allows significant radiative emission and additional light absorption, leading to remarkably enhanced current efficiency," said Professor Byeong-Su Kim, a senior author of the paper.
According to the researchers, there are few types of metal nanoparticles that can enhance performance in PLEDs and PSCs at the same time because these two types of OEDs require materials that exhibit contrasting properties.
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