Russian Science Foundation grant goes to a project directed by a young researcher at the cluster of the laboratories of Hybrid Photonic Nanomaterials and Nano-Bioengineering

The project on Two-Photon Processes in a Hybrid Material Based on Semiconductor Quantum Dots and Plasmonic Nanostructures to Be Used in Photovoltaics and Optoelectronics has won the Russian Science Foundation grant competition for Researches Carried out by Groups Directed by Young Researchers. Viktor Krivenkov, a young researcher at the Laboratory of Nano-Bioengineering who has just defended his PhD thesis, is the project's principal investigator.

The project essentially consists in designing a hybrid material based on gold nanorods electrostatically or chemically bound to water-soluble multishell quantum dots, analyzing the absorption, transfer, and conversion of light energy in this material, and applying it to developing prototypes of novel, high-performance photovoltaic and optoelectronic devices.

The wide absorption spectrum and large absorption cross section characteristic of quantum dots allow the efficiency of light to electricity conversion to be considerably enhanced in photovoltaic cells based on these nanoparticles. In addition, an extremely wide two-photon absorption cross section of quantum dots makes them a promising material for nonlinear-optical devices operating in the two-photon excitation mode. This will make it possible to convert radiation of the infrared range, where traditional photovoltaic systems are almost inefficient, into visible light. Plasmonic nanoparticles of noble metals—gold nanorods in the given case—have even larger absorption cross sections than quantum dots, but their fluorescence quantum yield is negligible. However, a local field enhancement in the vicinity of plasmonic nanoparticles enhances the light absorbance of nearby quantum dots by an order of magnitude provided that their spectra overlap. If two-photon absorption occurs, the effect is even stronger, because the increase in absorbance is proportional to the fourth degree of the field intensity in this case.

 

Another effect, which is still poorly understood but useful for photovoltaics, is observed in this hybrid system. The probability of biexciton excitation of a quantum dot, when it absorbs one photon and then emits two ones, rises in the vicinity of a plasmonic particle. Plasmonic nanoparticles can also increase the quantum yield of the quantum dots' biexciton luminescence, which is normally limited because of the Coulomb interaction between the excited charges. The use of biexciton excitation can make the quantum efficiency of solar cells higher than 100% in the spectral region where the photon energy is twice or more as large as the quantum dot's band gap.

The study of the parameters determining the strengths of these effects will provide insight into the basic processes underlying them and develop novel photovoltaic and optoelectronic devices with an unprecedentedly efficient light conversion.

The grants allotted in the framework of the Presidential Program of Research Projects Implemented by Leading Scientists, Including Young Researchers are intended for supporting both basic and exploratory research (http://rscf.ru/sites/default/files/docfiles/izveshenie_P2.pdf).

Contacts:

Viktor A. Krivenkov, junior researcher (vkrivenkov@list.ru)

Maria G. Korenkova, director of external relations (MGKorenkova@mephi.ru)

Laboratory of Nano-Bioengineering, Moscow Engineering Physics Institute
31 Kashirskoe shosse, 115409 Moscow, Russian Federation
http://www.lnbe.mephi.ru/en

 
 
 
© 2012 Laboratory of Nano-BioEngineering