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Topic Name: A new nanoparticle technique : Improve nanoparticles palacios
Category: Organic electronics
Research persons: Dr. Rodrigo Palacios,Paul F. Barbara,Allen J. Bard
Location: The University of Texas at Austin
Microelectronics Research CenterRoom # MRC 1.606F10100 Burnet Road Bldg 160,Austin, TX 78758-4445, United States
Details
Devices made from plastic semiconductors, like solar cells and light-emitting
diodes (LEDs), could be improved based on information gained using a new
nanoparticle technique developed at The University of Texas at Austin.As
electrical charges travel through plastic semiconductors, they can be trapped
much like a marble rolling on a bumpy surface becomes trapped in a deep hole.
These traps of charges are known as “deep traps,” and they are not well
understood.
Deep traps can be desired, as in the case of plastic semiconductors used for
memory devices, but they can also decrease the efficiency of the material to
conduct electrical charges. In the case of solar cells, deep traps can decrease
the efficiency of the conversion of light into electricity.
To further explore the deep trap phenomenon, a group of scientists led by
Professors of Chemistry and Biochemistry Paul Barbara and Allen Bard developed a
single-particle technique to study small portions of semiconductor material at
the nanoscale.
The scientists reported their findings in the advanced online issue of the
journal Nature Materials.
“Our results strongly suggest that deep traps are formed in plastic
semiconductors by a charge induced chemical reaction,” says Dr. Rodrigo
Palacios, lead author and post-doctoral fellow at the Center for Nano and
Molecular Science and Technology. “These traps were not there in the uncharged
pristine material.”
Deep traps could be caused by defects in the semiconductor material—either
native to the material or introduced impurities—with special properties that
encourage charge trapping. The traps also could develop over the life of the
semiconductor.
Previous techniques used to study deep traps have generally involved
completed semiconductor devices, which Palacios says creates complications due
to the complexity of a functional device.
For the current study, Palacios used a conjugated polymer (plastic
semiconductor) material known as F8BT, which is commercially available and has
promising applications in organic LEDs and solar cells.
He produced particles of F8BT with diameters about one-ten thousandth that of
a human hair. He then shone light on the nanoparticles and measured changes in
intensity of the resulting fluorescence. (This type of semiconductor material
takes in light energy and releases part of this energy as light of a different
color.)
Palacios observed deep traps forming as he electrochemically charged and
discharged the semiconductor nanoparticles. The deep traps led to decreases in
light emission from the material.
“With our new technique, we got detailed information on how these deep traps
are formed and how long they live,” says Palacios. “In principle, this kind of
information can be used to improve devices made out of these conjugated
polymers, designing new materials that can avoid these deep traps or materials
that might be able to form these deep traps better.”
About Researchers:
Dr. Rodrigo Palacios,
Center for Nano and Molecular Science and Technology,
512-471-5535, rodpalacios@mail.utexas.edu; Lee Clippard,
Public Affairs, 512-232-0675,
news@cns.utexas.edu
Paul F. Barbara
p.barbara@mail.utexas.edu
Analytical Chemistry, Physical Chemistry
Professor, Faculty
Director, Center for Nano- and Molecular Science and Technology
Richard J. V. Johnson-Welch Regents Chair
Contact Information
Dept. of Chemistry & Biochemistry
1 University Station A5300
Austin, TX 78712-0165
PHONE: (512) 471-3949
FAX: (512) 471-8696
Allen J. Bard
ajbard@mail.utexas.edu
Analytical Chemistry
Professor, Faculty
Director, Center for Electrochemistry
Norman Hackerman-Welch Regents Chair
Dept. of Chemistry & Biochemistry
1 University Station A5300
Austin, TX 78712-0165
PHONE: (512) 471-3949
FAX: (512) 471-8696
Funded:
The University of Texas at Austin has one of the largest and most successful
research programs in
nanotechnology world-wide. Over 450 researchers, in nine departments and
65 faculty research groups are working at the forefront of such exciting areas
as nanoelectronics, nano biology and medicine, nano structured polymers,
nanoparticle synthesis, nanotechnology for energy needs (e.g. for
photovoltaics, fuel cells and catalysis), nano applications to spintronics and
plasmonics, nano imprint lithography, nano tube research just to name a few of
the main areas.
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