Semiconductor nanocrystals or also called quantum dots exhibit outstanding optical properties compared to organic dyes. Due to the quantum confinement their emission color can be continuously tuned from the ultraviolet to the near infrared range by changing the size and chemical composition.
They exhibit a broad absorption spectrum, a narrow emission band and large absorption cross sections. Their surface can be covered by a few monolayers of different semiconductor materials in such a way that we can either improve their luminescent properties and stability or avoid the fluorescence to obtain charge carriers. The latter effect opens tremendous alternatives in photovoltaics. Due to their optical properties, semiconductor nanoparticles are studied in different disciplines, from optics to biomedicine.
Thanks to a remarkable effort in the synthetic activities in the last 20 years, we can nowadays produce nanoparticles of different materials controlling their size, shape, and surface properties. Examples of nanoparticles produced by non hydrolytic colloidal synthetic methods are CdS, CdTe, InP, GaAs, PbS, or PbSe. However, the most studied system is CdSe, with tunable emission from blue to red. Due to the synthetic approach (hot injection method), the surface of these nanoparticles is capped with an organic shell that protects them and makes them stable in non-polar organic solvents. It is also possible to controllably replace the initial organic shell for water compatible ones. The organic shell plays a relevant role in the quantum efficiency of the nanoparticles and their stability in different media. However, this shell prevents high electrical conduction.
Carbon nanotubes are another example of nanomaterials with extraordinary electrical properties. They consist of one or several rolled up graphene layers. In the case of a single layer they are called single-wall and multi-wall when several layers are rolled-up. Hybrid materials composed of semiconductor nanoparticles and carbon nanotubes combine the high absorption properties of the former and the high electrical conductivity of the latter. One of the main drawbacks in the formation of such hybrid structures focuses on the type of interaction between them. Most of the existing procedures involve the growth of nanoparticles on previous defect sites provoked on the surface or edges of carbon nanotubes by aggressive chemical means. These aggressive treatments render an oxidized nanotube surface or even structural damage that deteriorates their outstanding electrical, mechanical, and optical properties significantly. Thus, supramolecular or electrostatic functionalisations are better approaches for photovoltaic applications.
Dr Beatriz H. Juárez, from IMDEA Nanoscience, works on the preparation of hybrid materials with high coverage without modifying the electrical properties of the tubes. Furthermore, the monodispersity of the nanoparticles with high crystallographic quality and a close contact between nanoparticles and nanotubes are also under investigation. The composites show photoelectrical response, injecting charge carriers in the nanotubes upon nanoparticle excitation. Although in an initial stage, the results obtained up to now points out the high potential of these composites to build up photovoltaic devices and solar cells.
B. H. Juárez, C. Klinke, A. Kornowski, H. Weller, Nano Letters, 2007, 7, 3564
IMDEA | alfa
Further reports about: > Cells > HYBRID > Hybrid Material > Nanoscience > Photovoltaics > SOLAR > Semiconductor > Semiconductor nanocrystals > carbon nanotubes > fluorescence > hydrolytic colloidal synthetic methods > light emitting diodes > luminescent properties > nanoparticles > photovoltaic devices > solar cells
First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory
Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Life Sciences
27.10.2016 | Life Sciences
27.10.2016 | Power and Electrical Engineering