Wednesday, July 24, 2013

Two-in-one solution for low cost polymer LEDs and solar cells

Two-in-one solution for low cost polymer LEDs and solar cells

July 22, 2013 — Considerable improvement in device performance of polymer-based optoelectronic devices is reported today by researchers from Ulsan National Institute of Science and Technology (UNIST), South Korea. The new plasmonic material, can be applied to both polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs), with world-record high performance, through a simple and cheap process.

The contrary demands of these devices mean that there are few metal nanoparticles that can enhance performance in PLEDs and PSCs at the same time.
Most semiconducting optoelectronic devices (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.
Due to the limited availability of raw materials and the complex processing required to manufacture OEDs based on inorganic materials, the cost of device fabrication is increasing. There is great interest in thin-film OEDs that are made from alternative semiconductors.
Among these materials, organic semiconductors have received much attention for use in next-generation OEDs because of the potential for low-cost and large-area fabrication using solution processing.
Despite extensive efforts to develop new materials and device architectures enhancing the performance of these devices, further improvements in efficiency are needed, before there can be widespread use and commercialization of these technologies.
The material prepared by the UNIST research team is easy to synthesize with basic equipment and has low-temperature solution processability. This low-temperature solution processability enables roll-to-roll mass production techniques and is suitable for printed electronic devices.

Journal Reference:
  1. Hyosung Choi, Seo-Jin Ko, Yuri Choi, Piljae Joo, Taehyo Kim, Bo Ram Lee, Jae-Woo Jung, Hee Joo Choi, Myoungsik Cha, Jong-Ryul Jeong, In-Wook Hwang, Myoung Hoon Song, Byeong-Su Kim, Jin Young Kim. Versatile surface plasmon resonance of carbon-dot-supported silver nanoparticles in polymer optoelectronic devicesNature Photonics, 2013; DOI: 10.1038/nphoton.2013.181

Scientists break record for thinnest light-absorber: May lead to more efficient, cheaper solar cells

Scientists break record for thinnest light-absorber: May lead to more efficient, cheaper solar cells

July 18, 2013 — Stanford University scientists have created the thinnest, most efficient absorber of visible light on record. The nanosize structure, thousands of times thinner than an ordinary sheet of paper, could lower the cost and improve the efficiency of solar cells, according to the scientists.

Their results are published in the current online edition of the journal Nano Letters.
"Achieving complete absorption of visible light with a minimal amount of material is highly desirable for many applications, including solar energy conversion to fuel and electricity," said Stacey Bent, a professor of chemical engineering at Stanford and a member of the research team. "Our results show that it is possible for an extremely thin layer of material to absorb almost 100 percent of incident light of a specific wavelength."
Thinner solar cells require less material and therefore cost less. The challenge for researchers is to reduce the thickness of the cell without compromising its ability to absorb and convert sunlight into clean energy.
For the study, the Stanford team created thin wafers dotted with trillions of round particles of gold. Each gold nanodot was about 14 nanometers tall and 17 nanometers wide.

Journal Reference:
  1. Carl Hägglund, Gabriel Zeltzer, Ricardo Ruiz, Isabell Thomann, Han-Bo-Ram Lee, Mark L. Brongersma, Stacey F. Bent. Self-Assembly Based Plasmonic Arrays Tuned by Atomic Layer Deposition for Extreme Visible Light AbsorptionNano Letters, 2013; 13 (7): 3352 DOI:10.1021/nl401641v