Navigation Links
New spectroscopy method could lead to better optical devices

PROVIDENCE, R.I. [Brown University] A multi-university research team has used a new spectroscopic method to gain a key insight into how light is emitted from layered nanomaterials and other thin films.

The technique, called energy-momentum spectroscopy, enables researchers to look at the light emerging from a thin film and determine whether it is coming from emitters oriented along the plane of the film or from emitters oriented perpendicular to the film. Knowing the orientations of emitters could help engineers make better use of thin-film materials in optical devices like LEDs or solar cells.

The research, published online on March 3 in Nature Nanotechnology, was a collaborative effort of Brown University, Case Western Reserve University, Columbia University, and the University of CaliforniaSanta Barbara.

The new technique takes advantage of a fundamental property of thin films: interference. Interference effects can be seen in the rainbow colors visible on the surface of soap bubbles or oil slicks. Scientists can analyze how light constructively and destructively interferes at different angles to draw conclusions about the film itself how thick it is, for example. This new technique takes that kind of analysis one step further for light-emitting thin films.

"The key difference in our technique is we're looking at the energy as well as the angle and polarization at which light is emitted," said Rashid Zia, assistant professor of engineering at Brown University and one of the study's lead authors. "We can relate these different angles to distinct orientations of emitters in the film. At some angles and polarizations, we see only the light emission from in-plane emitters, while at other angles and polarizations we see only light originating from out-of-plane emitters."

The researchers demonstrated their technique on two important thin-film materials, molybdenum disulfide (MoS2) and PTCDA. Each represents a class of materials that shows promise for optical applications. MoS2 is a two-dimensional material similar to graphene, and PTCDA is an organic semiconductor. The research showed that light emission from MoS2 occurs only from in-plane emitters. In PTCDA, light comes from two distinct species of emitters, one in-plane and one out-of-plane.

Once the orientation of the emitters is known, Zia says, it may be possible to design structured devices that maximize those directional properties. In most applications, thin-film materials are layered on top of each other. The orientations of emitters in each layer indicate whether electronic excitations are happening within each layer or across layers, and that has implications for how such a device should be configured.

"If you were making an LED using these layered materials and you knew that the electronic excitations were happening across an interface," Zia said, "then there's a specific way you want to design the structure to get all of that light out and increase its overall efficiency."

The same concept could apply to light-absorbing devices like solar cells. By understanding how the electronic excitations happen in the material, it could be possible to structure it in a way that coverts more incoming light to electricity.

"One of the exciting things about this research is how it brought together people with different expertise," Zia said. "Our group's expertise at Brown is in developing new forms of spectroscopy and studying the electronic origin of light emission. The Kymissis group at Columbia has a great deal of expertise in organic semiconductors, and the Shan group at Case Western has a great deal of expertise in layered nanomaterials. Jon Schuller, the study's first author, did a great job in bringing all this expertise together. Jon was a visiting scientist here at Brown, a postdoctoral fellow in the Energy Frontier Research Center at Columbia, and is now a professor at UCSB."


Contact: Kevin Stacey
Brown University

Related biology technology :

1. Chemical Imaging Spectroscopy is the Focus for Pittcon 2013 Waters Symposium
2. Elsevier Announces the Launch of a New Journal: Methods in Oceanography
3. Rigaku Publishes EDXRF Method for Iron in Ore Materials
4. Rigaku Announces Method for Quantitative Elemental Analysis of Low-Alloy Steel with the Rigaku ZSX Primus III+ WDXRF Spectrometer
5. University of Colorado Cancer Center Study Shows the Preferred Feeding Method is not the Medically Best in Malnourished Pediatric Cancer Patients
6. Rigaku publishes new WDXRF Application: Determination of Metals in Copper Concentrate by Advanced Correction Method for Fused Beads
7. Unusual Method on How to Get Rid of Bed Bugs Without Pesticides Has Been Released To The Public, Explains
8. Rigku Publishes New Method for Quantitative Analysis of Cast Iron Using the ZSX Primus III+
9. Rigaku Publishes method for Determination of Sulfur in Bio-gasoline
10. Kitware to Develop Novel Neuroimage Processing Methods for Traumatic Brain Injury
11. What Is The Best Flea Control Method? Exposes The Truth
Post Your Comments:
Related Image:
New spectroscopy method could lead to better optical devices
(Date:12/1/2015)... , Dec. 1, 2015  CardioCell LLC, a ... stem cells for cardiovascular indications, intends to proceed ... based on recommendations from a Heart Failure Advisory ... Scientific Advisory Board members . In a ... Phase IIa safety and efficacy data from CardioCell,s ...
(Date:12/1/2015)... ... December 01, 2015 , ... ... backed, age-defying products, is featured as the cover story and throughout Success ... unrivaled opportunities that Nerium provides. Success from Home magazine routinely features successful ...
(Date:12/1/2015)... -- Dr. Harry Lander , President of Regen, expands ... Science Officer and recruits five distinguished scientists to ... President of Regen, expands his role to include ... five distinguished scientists to join advisory team --> ... include serving as Chief Science Officer ...
(Date:12/1/2015)... , December 1, 2015 ... addition of the  "2016 U.K. Virology and ... Forecasts for 100 Tests, Supplier Shares by ...  report to their offering.  --> ... the  "2016 U.K. Virology and Bacteriology Testing ...
Breaking Biology Technology:
(Date:10/29/2015)... Calif. , Oct. 29, 2015  The J. ... new report titled, "DNA Synthesis and Biosecurity: Lessons Learned ... the Department of Health and Human Services guidance for ... in 2010. --> ... it also has the potential to pose unique biosecurity ...
(Date:10/29/2015)... , Oct. 29, 2015  Connected health pioneer, ... driving the explosion of technology-enabled health and wellness, and ... new book, The Internet of Healthy Things ... sensors or smartphones even existed, Dr. Kvedar, vice president, ... of health care delivery, moving care from the hospital ...
(Date:10/27/2015)... , Oct. 27, 2015 In the present ... of concern for various industry verticals such as banking, ... to the growing demand for secure & simplified access ... ,sectors, such as hacking of bank accounts, misuse of ... equipment such as PC,s, laptops, and smartphones are expected ...
Breaking Biology News(10 mins):