Navigation Links
Pairing quantum dots with fullerenes for nanoscale photovoltaics

UPTON, NY - 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.

"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. Please contact Kimberley Elcess at (631) 344-4151, or, for more information.


Contact: Karen McNulty Walsh
DOE/Brookhaven National Laboratory

Related biology technology :

1. Diamonds shine in quantum networks
2. Reportlinker Adds Quantum Dots: Technologies and Global Markets
3. Etched quantum dots shape up as single photon emitters, NIST tests show
4. Quantum hot potato: NIST researchers entice 2 atoms to swap smallest energy units
5. Dr. Stefan Strauf of physics at Stevens receives NSF CAREER Award for quantum research
6. UCSB physicists challenge classical world with quantum-mechanical implementation of shell game
7. TU scientists in Nature: Better control of building blocks for quantum computer
8. Ben-Gurion University nano researcher to receive prestigious award for laser science and quantum physics
9. Quantum computers a step closer to reality thanks to new finding
10. Quantum entanglement in photosynthesis and evolution
11. This little light of mine: Changing the color of single photons emitted by quantum dots
Post Your Comments:
(Date:11/25/2015)... 25, 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS; ... and prospects remain fundamentally strong and highlights the ... recently received DSMB recommendation to continue the ZoptEC ... of the final interim efficacy and safety data ... in men with heavily pretreated castration- and Taxane-resistant ...
(Date:11/24/2015)... LUMPUR, Malaysia , Nov. 24, 2015 /PRNewswire/ ... global contract research organisation (CRO) market. The trend ... result in lower margins but higher volume share ... increased capacity and scale, however, margins in the ... Research Organisation (CRO) Market ( ), ...
(Date:11/24/2015)... ... November 24, 2015 , ... Copper is an ... is bound to proteins, copper is also toxic to cells. With a $1.3 ... Institute (WPI) will conduct a systematic study of copper in the bacteria Pseudomonas ...
(Date:11/24/2015)... ... November 24, 2015 , ... This fall, global software solutions leader ... five states to develop and pitch their BIG ideas to improve health and wellness ... competing for votes to win the title of SAP's Teen Innovator, an all-expenses paid ...
Breaking Biology Technology:
(Date:10/29/2015)... 2015 Daon, a global leader in mobile ... a new version of its IdentityX Platform , ... America have already installed IdentityX v4.0 and ... FIDO UAF certified server component as an ... FIDO features. These customers include some of the largest ...
(Date:10/29/2015)... 2015  Connected health pioneer, Joseph C. Kvedar ... technology-enabled health and wellness, and the business opportunities that ... The Internet of Healthy Things . Long before ... existed, Dr. Kvedar, vice president, Connected Health, Partners HealthCare, ... moving care from the hospital or doctor,s office into ...
(Date:10/29/2015)... Today, LifeBEAM , a leader ... a global leader in technical performance sports clothing ... advanced bio-sensing technology. The hat will allow fitness ... biometrics to improve overall training performance. As a ... bring together the most advanced technology, extensive understanding ...
Breaking Biology News(10 mins):