PRESS-NEWS.org - Press Release Distribution
FREE PRESS RELEASES DISTRIBUTION

Scientists achieve first direct observations of excitons in motion

Technique developed at MIT reveals the motion of energy-carrying quasiparticles in solid material

2014-04-16
(Press-News.org) A quasiparticle called an exciton — responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits — has been understood theoretically for decades. But exciton movement within materials has never been directly observed.

Now scientists at MIT and the City College of New York have achieved that feat, imaging excitons' motions directly. This could enable research leading to significant advances in electronics, they say, as well as a better understanding of natural energy-transfer processes, such as photosynthesis.

The research is described this week in the journal Nature Communications, in a paper co-authored by MIT postdocs Gleb Akselrod and Parag Deotare, professors Vladimir Bulovic and Marc Baldo, and four others.

"This is the first direct observation of exciton diffusion processes," Bulovic says, "showing that crystal structure can dramatically affect the diffusion process."

"Excitons are at the heart of devices that are relevant to modern technology," Akselrod explains: The particles determine how energy moves at the nanoscale. "The efficiency of devices such as photovoltaics and LEDs depends on how well excitons move within the material," he adds.

An exciton, which travels through matter as though it were a particle, pairs an electron, which carries a negative charge, with a place where an electron has been removed, known as a hole. Overall, it has a neutral charge, but it can carry energy. For example, in a solar cell, an incoming photon may strike an electron, kicking it to a higher energy level. That higher energy is propagated through the material as an exciton: The particles themselves don't move, but the boosted energy gets passed along from one to another.

While it was previously possible to determine how fast, on average, excitons could move between two points, "we really didn't have any information about how they got there," Akselrod says. Such information is essential to understanding which aspects of a material's structure — for example, the degree of molecular order or disorder — might facilitate or slow that motion.

"People always assumed certain behavior of the excitons," Deotare says. Now, using this new technique — which combines optical microscopy with the use of particular organic compounds that make the energy of excitons visible — "we can directly say what kind of behavior the excitons were moving around with." This advance provided the researchers with the ability to observe which of two possible kinds of "hopping" motion was actually taking place.

"This allows us to see new things," Deotare says, making it possible to demonstrate that the nanoscale structure of a material determines how quickly excitons get trapped as they move through it.

For some applications, such as LEDs, Deotare says, it is desirable to maximize this trapping, so that energy is not lost to leakage; for other uses, such as solar cells, it is essential to minimize the trapping. The new technique should allow researchers to determine which factors are most important in increasing or decreasing this trapping.

"We showed how energy flow is impeded by disorder, which is the defining characteristic of most materials for low-cost solar cells and LEDs," Baldo says.

While these experiments were carried out using a material called tetracene — a well-studied archetype of a molecular crystal — the researchers say that the method should be applicable to almost any crystalline or thin-film material. They expect it to be widely adopted by researchers in academia and industry.

"It's a very simple technique, once people learn about it," Akselrod says, "and the equipment required is not that expensive."

Exciton diffusion is also a basic mechanism underlying photosynthesis: Plants absorb energy from photons, and this energy is transferred by excitons to areas where it can be stored in chemical form for later use in supporting the plant's metabolism. The new method might provide an additional tool for studying some aspects of this process, the team says.

INFORMATION: Written by David L. Chandler, MIT News Office

The work was supported by the U.S. Department of Energy and by the National Science Foundation, and used facilities of the Eni-MIT Solar Frontiers Center.


ELSE PRESS RELEASES FROM THIS DATE:

Wind Over Water Jewelry Project Launch on Indiegogo: Fashion-forward, Baby-friendly and Socially Minded Jewelry Designs For Moms

2014-04-16
Wind Over Water Jewelry designs are exclusively through the Indiegogo Campaign. Providing fashion-forward, baby-friendly and socially-minded jewelry options to mothers. FASHION FORWARD - an upgrade to any outfit plus unique asymmetrical designs always allow mom to remember on what side she last nursed BABY FRIENDLY - materials that are non-toxic plus something that perks baby's interest SOCIALLY MINDED - a partnership that helps impoverished women now plus creates a new future through access to education. That's a lot for a necklace! Fashion-Forward Jewelry Our ...

Richmond Family Dentistry Wins Consecutive Talk of the Town Awards

2014-04-16
For the third straight year, Richmond Family Dentistry has received the prestigious Talk of the Town Customer Satisfaction Award in the Health & Medical -- Dentists. Cheryl Billingsley, DDS, MAGD, ND, and the team at Richmond Family Dentistry were honored with the award after earning the highest possible customer satisfaction rating of 5 stars. The Talk of the Town Awards, presented by Talk of the Town News, honor companies and professionals that provide excellent customer service as reported by their customers through no-cost, user-review websites, blogs, social ...

Florida Matchmaker "Raises the Bar" to help Singles Find Love

2014-04-16
Kelly Leary isn't "your grandmother's matchmaker." In fact, she's brought this ancient talent that goes back thousands of years into the 21st century with her new company, Revolution Dating. "Since the advent of the internet, dating has gotten way more complicated than it ever was," said Leary, who has been a fixture on the matchmaking scene in South Florida and the Treasure Coast for 23 years. "While on the one hand there are more choices than ever, on the other hand you have no idea who you're meeting. Plus, most people don't have the kind of time to waste that internet ...

UNIFOSA Debuts latest 12Gb/s SAS JBOD

2014-04-16
UNIFOSA CORP. launched the 2U 24Bays 12Gb/s SAS JBOD, EP-2246J/JD-SCSC, which offers high density storage, hardware redundancy and easily integrates into versatile applications that request high performance and high scalability. The EP-2246J/JD-SCSC accommodates the latest SAS 3.0 12Gb/s interface which boost up the throughput up to 4,800MB/s per host. Based on this powerful performance, EP-2246J/JD-SCSC can efficiently meet demands for intensive data access applications, virtualization and Windows Server 2012 installation, and video edition related applications. The ...

The Brookeside Group Named 'Customer Service Consulting Practice of the Year' at 2013 Stevie Awards

2014-04-16
The Brookeside Group, a consulting, training and technology firm specializing in client relationship management, took home the Gold Stevie Awards medal for 'Customer Service Consulting Practice of the Year' at the awards ceremony on Feb. 25, 2013 in Las Vegas. The Bostonbased firm was also awarded a Bronze medal for 'Customer Service Training Practice of the Year.' "Winning 'Customer Service Consulting Practice of the Year' is a testament to our commitment to our clients and our continued success helping them create and maintain strong business relationships," said Tom ...

Grand Opening of GreenBliss Lifestyle & Wellness Center

2014-04-16
Bliss Cureton, owner and founder of GreenBliss will open GreenBliss Lifestyle & Wellness store on April 17, 2014. The new retail location is in the Avenue of Fashion District in Detroit and will be one of the many new locally sought after shops. The store will carry an array of non-toxic cleaning supplies, eco-friendly home goods and offer concrete transformation services. The retail store is located in the University District, one of Detroit's most distinguished areas and aims to attract locals who want to live an eco-friendly lifestyle without breaking the bank. ...

Marie Oh Huber Attended 6th Annual DirectWomen Board Institute In New York

2014-04-16
Marie Oh Huber, Senior Vice President, General Counsel and Secretary for Agilent Technologies, Inc., attended the DirectWomen Board Institute from January 22-24 in New York City. DirectWomen, an organization formed to position women lawyers to serve on boards of public companies, selects a group of qualified women lawyers from a competitive pool of applicants across the country to participate in the three-day program. At the DirectWomen Board Institute Huber attended informational sessions on key issues facing current and future corporate directors and had the opportunity ...

Royal Dynamite Launches New Limited Edition Freetown Collection

2014-04-16
Royal Dynamite, a collaborative and unique t-shirt company that combines popular culture and community, is launching the Freetown collection of limited edition t-shirts and hats in time to commemorate Sierra Leone's 53rd Independence Day. Freetown, the capital city of Sierra Leone, was founded in 1792 as a colony for freed slaves by African-Americans, Africans and West Indians. Since its inception in 1792, a lot of historical events have taken place including its independence in 1961 and a 10 year civil war. Today, however, with a new era and powerful generation full ...

Bob Faw's "Energize" Message Reaches Worldwide Audience

2014-04-16
Bob Faw's message of simple yet effective positive change is resonating with people worldwide, driving his book, "Energize: Ignite Passion and Performance With User-Friendly Brain Tools" to No. 1 in two Amazon categories. Eventually ending up as #3 overall in Amazon Kindle Free with more than 34,500 e-book copies downloaded since April 1. "I'm blown away by the response to the book," said Bob. "I love to help people transform their lives in a positive way. It's the most deeply satisfying thing in my life. I wrote 'Energize' because I want to reach more people than I ...

Hundreds Attend Meadow Glen Grand Opening and Tour New GenSmart Suite Homes by Pardee

2014-04-16
The grand opening of Pardee Homes' newest neighborhood, Meadow Glen at Canyon Hills in Lake Elsinore attracted hundreds of home shoppers who were treated to an array of activities, including tours of the new GenSmart Suite model homes, a cooking demonstration and complimentary lunch served from The Grilled Cheese Truck of Orange County. Steady traffic on grand opening day and throughout the weekend resulted in sale of all 8 homes in the first phase release followed two weeks later by 10 homes sold in the second release. The third phase release is anticipated to take place ...

LAST 30 PRESS RELEASES:

Scientists model 'true prevalence' of COVID-19 throughout pandemic

New breakthrough to help immune systems in the fight against cancer

Through the thin-film glass, researchers spot a new liquid phase

Administering opioids to pregnant mice alters behavior and gene expression in offspring

Brain's 'memory center' needed to recognize image sequences but not single sights

Safety of second dose of mRNA COVID-19 vaccines after first-dose allergic reactions

Changes in disparities in access to care, health after Medicare eligibility

Use of high-risk medications among lonely older adults

65+ and lonely? Don't talk to your doctor about another prescription

Exosome formulation developed to deliver antibodies for choroidal neovascularization therapy

Second COVID-19 mRNA vaccine dose found safe following allergic reactions to first dose

Plant root-associated bacteria preferentially colonize their native host-plant roots

Rare inherited variants in previously unsuspected genes may confer significant risk for autism

International experts call for a unified public health response to NAFLD and NASH epidemic

International collaboration of scientists rewrite the rulebook of flowering plant genetics

Improving air quality reduces dementia risk, multiple studies suggest

Misplaced trust: When trust in science fosters pseudoscience

Two types of blood pressure meds prevent heart events equally, but side effects differ

New statement provides path to include ethnicity, ancestry, race in genomic research

Among effective antihypertensive drugs, less popular choice is slightly safer

Juicy past of favorite Okinawan fruit revealed

Anticipate a resurgence of respiratory viruses in young children

Anxiety, depression, burnout rising as college students prepare to return to campus

Goal-setting and positive parent-child relationships reduce risk of youth vaping

New research identifies cancer types with little survival improvements in adolescents and young adul

Oncotarget: Replication-stress sensitivity in breast cancer cells

Oncotarget: TERT and its binding protein: overexpression of GABPA/B in gliomas

Development of a novel technology to check body temperature with smartphone camera

The mechanics of puncture finally explained

Extreme heat, dry summers main cause of tree death in Colorado's subalpine forests

[Press-News.org] Scientists achieve first direct observations of excitons in motion
Technique developed at MIT reveals the motion of energy-carrying quasiparticles in solid material