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Laser Plasma Process Could Advance Optoelectronic Materials

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A novel nanohybrid structure synthesized using a pulsed laser ablation technique could yield a new generation of optoelectronic switches, fast photodetectors and third-generation solar devices.

Research on the photoelectronic properties of semiconductor nanoparticles, such as lead sulfide (PbS), has grown significantly over recent years. Combining PbS with carbon nanotubes for generating photocurrent has proven effective, but the conventional synthesis methods have limitations.

Now scientists at the INRS Énergie Matériaux Télécommunications Research Centre are combining nanoparticles using a relatively simple process that offers considerable latitude for creating other nanohybrids for a variety of applications. The pulsed laser ablation (PLA) technique produces very pure nanostructures with greater control of nanohybrid characteristics.

“When chemically synthesizing nanohybrids, researchers used ligands, which prevented the charge transfer dynamics from nanoparticles to nanotubes,” said professor My Ali El Khakani. Ligands reduce photoresponse efficiency and increase the reaction time — two effects that were not observed in nanohybrids produced using the INRS PLA method, since PbS is in direct atomic contact with the nanotubes’ surface.

“At the beginning, we didn’t know if the nanohybrids would form in such a way as to enable their effective use for photodetection,” said INRS doctoral student Ibrahima Ka. “By optimizing our approach, we developed nanohybrids whose photoactivity can be almost tailored at will.”

Integrating the nanohybrid material into functional photoconductive devices resulted in a stronger photoresponse than was possible with other methods. The INRS researchers achieved photoresponse values as high as 670 percent at 633 nm and 1350 percent at 405 nm; in these conditions, other nanohybrids did not exceed 37 percent.

When illuminated by a laser, the material’s photocurrent response time is 1000 to 100,000 times faster than that of current nanohybrids.

The findings were reported in Advanced Materials (doi: 10.1002/adma.201290298)

For more information, visit: www.inrs.ca
Rocky Mountain Instruments - Laser Optics MR

Published: February 2013
Glossary
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
photocurrent
The current that flows through a photosensitive device, such as a photodiode, as the result of exposure to radiant power.
quantum dots
A quantum dot is a nanoscale semiconductor structure, typically composed of materials like cadmium selenide or indium arsenide, that exhibits unique quantum mechanical properties. These properties arise from the confinement of electrons within the dot, leading to discrete energy levels, or "quantization" of energy, similar to the behavior of individual atoms or molecules. Quantum dots have a size on the order of a few nanometers and can emit or absorb photons (light) with precise wavelengths,...
AmericasBasic ScienceCanadacarbon nanotubesCommunicationsenergygreen photonicsIbrahima KaINRSMaterialsMy Ali El KhakaninanonanohybridsOpticsoptoelectronic switchesPbSphotoconductive devicesphotocurrentphotoresponsePLApulsed laser ablationpulsed lasersquantum dotsResearch & TechnologySensors & DetectorsLasers

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