Featured Research

from universities, journals, and other organizations

Pairing quantum dots with fullerenes for nanoscale photovoltaics

Date:
May 10, 2011
Source:
DOE/Brookhaven National Laboratory
Summary:
In a step toward engineering ever-smaller electronic devices, scientists have assembled nanoscale pairings of particles that show promise as miniaturized power sources. Composed of light-absorbing, colloidal quantum dots linked to carbon-based fullerene nanoparticles, these tiny two-particle systems can convert light to electricity in a precisely controlled way.

Left: Photoinduced electron transfer occurring in quantum dot-bridge-fullerene hererodimers and observed with single molecule microscopy. Right: Control of electron transfer (ET) rate by variation of interparticle distance (R, upper panel) and quantum dot size (D, lower panel).
Credit: Image courtesy of DOE/Brookhaven National Laboratory

In a step toward engineering ever-smaller electronic devices, scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have assembled nanoscale pairings of particles that show promise as miniaturized power sources. Composed of light-absorbing, colloidal quantum dots linked to carbon-based fullerene nanoparticles, these tiny two-particle systems can convert light to electricity in a precisely controlled way.

Related Articles


"This is the first demonstration of a hybrid inorganic/organic, dimeric (two-particle) material that acts as an electron donor-bridge-acceptor system for converting light to electrical current," said Brookhaven physical chemist Mircea Cotlet, lead author of a paper describing the dimers and their assembly method in Angewandte Chemie.

By varying the length of the linker molecules and the size of the quantum dots, the scientists can control the rate and the magnitude of fluctuations in light-induced electron transfer at the level of the individual dimer. "This control makes these dimers promising power-generating units for molecular electronics or more efficient photovoltaic solar cells," said Cotlet, who conducted this research with materials scientist Zhihua Xu at Brookhaven's Center for Functional Nanomaterials (CFN).

Scientists seeking to develop molecular electronics have been very interested in organic donor-bridge-acceptor systems because they have a wide range of charge transport mechanisms and because their charge-transfer properties can be controlled by varying their chemistry. Recently, quantum dots have been combined with electron-accepting materials such as dyes, fullerenes, and titanium oxide to produce dye-sensitized and hybrid solar cells in the hope that the light-absorbing and size-dependent emission properties of quantum dots would boost the efficiency of such devices. But so far, the power conversion rates of these systems have remained quite low.

"Efforts to understand the processes involved so as to engineer improved systems have generally looked at averaged behavior in blended or layer-by-layer structures rather than the response of individual, well-controlled hybrid donor-acceptor architectures," said Xu.

The precision fabrication method developed by the Brookhaven scientists allows them to carefully control particle size and interparticle distance so they can explore conditions for light-induced electron transfer between individual quantum dots and electron-accepting fullerenes at the single molecule level.

The entire assembly process takes place on a surface and in a stepwise fashion to limit the interactions of the components (particles), which could otherwise combine in a number of ways if assembled by solution-based methods. This surface-based assembly also achieves controlled, one-to-one nanoparticle pairing.

To identify the optimal architectural arrangement for the particles, the scientists strategically varied the size of the quantum dots -- which absorb and emit light at different frequencies according to their size -- and the length of the bridge molecules connecting the nanoparticles. For each arrangement, they measured the electron transfer rate using single molecule spectroscopy.

"This method removes ensemble averaging and reveals a system's heterogeneity -- for example fluctuating electron transfer rates -- which is something that conventional spectroscopic methods cannot always do," Cotlet said.

The scientists found that reducing quantum dot size and the length of the linker molecules led to enhancements in the electron transfer rate and suppression of electron transfer fluctuations.

"This suppression of electron transfer fluctuation in dimers with smaller quantum dot size leads to a stable charge generation rate, which can have a positive impact on the application of these dimers in molecular electronics, including potentially in miniature and large-area photovoltaics," Cotlet said.

"Studying the charge separation and recombination processes in these simplified and well-controlled dimer structures helps us to understand the more complicated photon-to-electron conversion processes in large-area solar cells, and eventually improve their photovoltaic efficiency," Xu added.

A U.S. patent application is pending on the method and the materials resulting from using the technique, and the technology is available for licensing. This work was funded by the DOE Office of Science.


Story Source:

The above story is based on materials provided by DOE/Brookhaven National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Zhihua Xu, Mircea Cotlet. Quantum Dot-Bridge-Fullerene Heterodimers with Controlled Photoinduced Electron Transfer. Angewandte Chemie International Edition, 2011; DOI: 10.1002/anie.201007270

Cite This Page:

DOE/Brookhaven National Laboratory. "Pairing quantum dots with fullerenes for nanoscale photovoltaics." ScienceDaily. ScienceDaily, 10 May 2011. <www.sciencedaily.com/releases/2011/05/110510111203.htm>.
DOE/Brookhaven National Laboratory. (2011, May 10). Pairing quantum dots with fullerenes for nanoscale photovoltaics. ScienceDaily. Retrieved November 27, 2014 from www.sciencedaily.com/releases/2011/05/110510111203.htm
DOE/Brookhaven National Laboratory. "Pairing quantum dots with fullerenes for nanoscale photovoltaics." ScienceDaily. www.sciencedaily.com/releases/2011/05/110510111203.htm (accessed November 27, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, November 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins