Industry News




 

02/22/2013

Silicon Nanocrystal LEDs

 
New applications for LED continue to make noise in the world of facility management and building operation.

Photo: F. Maier-Flaig, KIT/LTI

LED lighting often manages to find its way into the facility management spotlight.  Scientists of KIT and the University of Toronto/Canada have now succeeded in manufacturing silicon-based light-emitting diodes (SiLEDs). They are free of heavy metals and can emit light in various colors. The team of chemists, materials researchers, nanoscientists, and opto-electronic experts presents its development in the “Nano Letters” journal (DOI: 10.1021/nl3038689).

Silicon dominates in the microelectronics and photovoltaics industries, but has been considered unsuitable for light-emitting diodes for some time. However, this is not true for nanoscopic dimensions: Minute silicon nanocrystals can produce light. These nanocrystals consist of a few hundred to thousand atoms and have a considerable potential as highly efficient light emitters, as was demonstrated by the team of Professor Uli Lemmer and Professor Annie K. Powell from KIT as well as Professor Geoffrey A. Ozin from the University of Toronto. In a joint project, the scientists have succeeded in manufacturing highly efficient light-emitting diodes from the silicon nanocrystals.

So far, manufacture of silicon light-emitting diodes has been limited to the red visible spectral range and the near infrared. As regards the efficiency of silicon diodes emitting red light, researchers from Karlsruhe are already top in the world. “Controlled manufacture of diodes emitting multicolor light, however, is an absolutely novelty,” says Florian Maier-Flaig, scientist of the Light Technology Institute (LTI) of KIT and doctoral student of the Karlsruhe School of Optics and Photonics (KSOP).

KIT scientists specifically adjust the color of the light emitted by the diodes by separating nanoparticles depending on their size. “Moreover, our light-emitting diodes have a surprising long-term stability that has not been reached before,” Maier-Flaig says. The increased service life of the components in operation is due to the use of nanoparticles of one size only. This enhances the stability of the sensitive thin-film components. Short circuits due to oversized particles are excluded.

The development made by the researchers from Karlsruhe and Toronto is also characterized by an impressing homogeneity of the luminous areas. The KIT researchers are among the few teams in the world that know how to manufacture such devices. “With the liquid-processed silicon LEDs that may potentially be produced on large areas as well as at low costs, the nanoparticle community enters new territory, the associated potentials of which can hardly be estimated today. But presumably, textbooks about semiconductor components have to be rewritten,” says Geoffrey A. Ozin, who is presently working as a KIT distinguished research fellow at KIT’s Center for Functional Nanostructures (CFN).

The SiLEDs have the advantage that they do not contain any heavy metals. In contrast to cadmium selenide, cadmium sulfide or lead sulfide used by other groups of researchers, the silicon used by this group for the light-emitting nanoparticles is not toxic. Moreover, it is available at low costs and highly abundant on earth.

 

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04/23/2014

A key part to curbing emissions is working with local and city officials, tenants, and other groups to help make entire communities more sustainable. BOMA International shares the following strategies for greening your facility and community.

04/21/2014

Lighting fixes target the bottom line.

04/16/2014

The U.S. Army plans to start development of a solar array that will provide about 25% of the annual installation electricity requirement of Fort Huachuca, Arizona.

04/15/2014

The EPA's annual greenhouse gas emissions report is now available.

04/14/2014

Are you what some would call a “climate-change denier”? If so, you'll want to read this.

04/10/2014
Los Angeles has remained the top city for ENERGY STAR certified building since 2008, while Washington, D.C. continues to hold onto second place for the fifth consecutive year, according to a new list released by the EPA.
04/09/2014
Green construction has grown massively over a short period of time.
04/07/2014
Field demonstrations of newly proven energy-efficient technologies are yielding valuable results for the U.S. Navy, helping it meet energy goals.
04/03/2014
Building owners in Chicago now have more options when it comes to getting their building energy data verified.
04/01/2014
According to a new report from Eaton, such outages are up 15% in 2013 over 2012 and over half of those surveyed believe that downtime could have been prevented.
03/31/2014
The newly revised ANSI/ASHRAE Standard 105-2014, Standard Methods of Determining, Expressing, and Comparing Building Energy Performance and Greenhouse Gas Emissions, aims to provide a consistent method of measuring, expressing, and comparing the energy performance of buildings.
03/27/2014
Facility managers face an every expanding array of sustainability choices and challenges, but for the next generation of FMs, green practices could be second nature as sustainability literacy enters the K-12 school system.
03/25/2014
While the economic recession explains the decline in sales in 2008 and 2009, it is much less clear why sales have continued to fall.
03/24/2014
University of Washington (UW) scientists have built the thinnest known LED that can be used as a source of light energy in electronics.
03/21/2014
Mississippi Governor Phil Bryant signed Senate Bill 2378 into law, effectively enacting the state’s first building code.
03/19/2014
In an attempt to improve building energy performance, the DOE’s National Renewable Energy Laboratory has released a web-based tool called the Technology Performance Exchange, or TPEx.
03/18/2014
Could green building practices pose unanticipated life-safety hazards?
03/13/2014
Worried about workplace violence in your facility? Researchers have discovered that “mindfully observing” high-risk employees can avert danger and workplace violence.
03/11/2014
Through the DOE’s Building Energy Codes Program, every dollar the DOE has spent on building energy codes over the past two decades has resulted in $400 in energy cost savings.
03/07/2014
It is possible to harvest energy from Earth's thermal infrared emission into outer space, according to new research from the Harvard School of Engineering and Applied Sciences.
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