Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UO-industry collaboration points to improved nanomaterials

21.11.2014

University of Oregon microscope puts spotlight on the surface structure of quantum dots for designing new solar devices

A potential path to identify imperfections and improve the quality of nanomaterials for use in next-generation solar cells has emerged from a collaboration of University of Oregon and industry researchers.


University of Oregon doctoral student Christian Gervasi, left, and Thomas Allen of VoxtelNano led a university-industry collaboration to create atomic-scale maps of the density of states in individual nanocrystals with a specially designed microscope. The maps promise a route to next-generation solar cells.

Credit: University of Oregon

To increase light-harvesting efficiency of solar cells beyond silicon's limit of about 29 percent, manufacturers have used layers of chemically synthesized semiconductor nanocrystals. Properties of quantum dots that are produced are manipulated by controlling the synthetic process and surface chemical structure.

This process, however, creates imperfections at the surface-forming trap states that limit device performance. Until recently, improvements in production quality have relied on feedback provided by traditional characterization techniques that probe average properties of large numbers of quantum dots.

"We want to use these materials in real devices, but they are not yet optimized," said co-author Christian F. Gervasi, a UO doctoral student.

In their study, detailed in the Journal of Physical Chemistry Letters, researchers investigated electronic states of lead sulfide nanocrystals. By using a specially designed scanning tunneling microscope, researchers created atomic-scale maps of the density of states in individual nanocrystals. This allowed them to pinpoint the energies and localization of charge traps associated with defects in the nanocrystal surface structure that are detrimental to electron propagation.

The microscope was designed in the lab of co-author George V. Nazin, a professor in the UO Department of Chemistry and Biochemistry. Its use was described in a previous paper in the same journal, in which Nazin's lab members were able to visualize the internal structures of electronic waves trapped by external electrostatic charges in carbon nanotubes.

"This technology is really cool," said Peter Palomaki, senior scientist for Voxtel Nanophotonics and co-author on the new paper. "When you really dig down into the science at a very fundamental level, this problem has always been an open-ended question. This paper is just the tip of the iceberg in terms of being able to understand what's going on."

The insight, he said, should help manufacturers tweak their synthesis of nanocrystals used in a variety of electronic devices. Co-author Thomas Allen, also a senior scientist at Voxtel, agreed. The project began after Allen heard Gervasi and Nazin discussing the microscope's capabilities.

"We wanted to see what the microscope could accomplish, and it turns out that it gives us a lot of information about the trap states and the depths of trap states in our quantum dots," said Allen, who joined Voxtel after completing the Industrial Internship Program in the UO's Materials Science Institute. "The information will help us fine-tune the ligand chemistry to make better devices for photovoltaics, detectors and sensors."

The trap states seen by the microscope in this project may explain why nanoparticle-based solar cells have not yet been commercialized, Nazin said.

"Nanoparticles are not always stable. It is a fundamental problem. When you synthesize something at this scale you don't necessarily get the same structure for all of the quantum dots. Working at the atomic scale can produce large variations in the electronic states. Our tool allows us to see these states directly and allow us to provide feedback on the materials."

Sony Corp. supported the research. Quantum dots were synthesized by VoxtelNanophotonics, a division of Voxtel Inc., which has research space in the UO's Lorry Lokey Laboratories. The microscope, which was described in a recent paper in the journal Review of Scientific Instruments, was built with funding from the National Science Foundation (grant DMR-0960211).

Co-authors with Gervasi, Allen, Palomaki and Nazin are Dmitry A. Kislitsyn and Jason D. Hackley, both doctoral students, and Ryuichiro Maruyama, a courtesy research associate in the Nanoscale Open Research Initiative of the UO's Department of Chemistry and Biochemistry.

Sources: George Nazin, assistant professor of physical chemistry, Department of Chemistry and Biochemistry, 541-346-2017, gnazin@uoregon.edu; Christian Gervasi, doctoral student, 541-346-8150, cgervasi@uoregon.edu; Peter Palomaki, senior scientist, VoxtelNano, a division of Voxtel Inc., 541-346-8131, peterp@voxtel-inc.com; and Thomas Allen, senior scientist, VoxtelNano, a division of Voxtel Inc., 541-346-8131

Note: The University of Oregon is equipped with an on-campus television studio with a point-of-origin Vyvx connection, which provides broadcast-quality video to networks worldwide via fiber optic network. In addition, there is video access to satellite uplink, and audio access to an ISDN codec for broadcast-quality radio interviews.

Previous release: Special UO microscope captures defects in nanotubes: http://uonews.uoregon.edu/archive/news-release/2014/10/special-uo-microscope-captures-defects-nanotubes

New paper abstract: http://pubs.acs.org/doi/abs/10.1021/jz5019465

About Voxtel: http://voxtel-inc.com/about-voxtel/

Nazin faculty page: http://chemistry.uoregon.edu/profile/gnazin/

Nazin Lab: https://wiki.uoregon.edu/display/Nazin/Nazin+Group

Department of Chemistry and Biochemistry: http://chemistry.uoregon.edu/

About the microscope: http://scitation.aip.org/content/aip/journal/rsi/85/10/10.1063/1.4897139

Jim Barlow | EurekAlert!

Further reports about: Biochemistry Nanocrystals materials nanomaterials quantum dots solar cells structure

More articles from Materials Sciences:

nachricht Robust and functional – surface finishing by suspension spraying
19.09.2017 | Fraunhofer-Institut für Keramische Technologien und Systeme IKTS

nachricht Graphene and other carbon nanomaterials can replace scarce metals
19.09.2017 | Chalmers University of Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

Im Focus: Artificial Enzymes for Hydrogen Conversion

Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.

Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

New quantum phenomena in graphene superlattices

19.09.2017 | Physics and Astronomy

A simple additive to improve film quality

19.09.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>