Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Gradient Multi-Layer Nano-films for Photovoltaic and other applications

GML (Gradient Multi-Layer) nano-film
GML (Gradient Multi-Layer) nano-film

Abstract:
Recently, a new type of nanostructure - GML (Gradient Multi-Layer) nano-film - attracted attention of the researchers in the solar cell industry. The properties of this structure can be used in design of more efficient and less expensive solar cells, as well as other nano-structured devices.

Gradient Multi-Layer Nano-films for Photovoltaic and other applications

Posted on October 7th, 2010

GML Nano films

Quantum Dots are spherical nano-particles (or nano-crystals) typically made of semiconductor or metal.

Nano-structured Materials (or Devices) typically contain two or more interpenetrating nano-scale networks (Bulk Hetero Junctions or BHJs) including Organic (Polymer Blends), Inorganic (Quantum Dots only), and Hybrid (Polymer with Embedded Quantum Dots).

Gradient Multi-Layer (GML) Nano-structure (or nano-film) is a stack of Quantum Dot layers arranged to form a size gradient, composition gradient, density gradient or composition/size modulation with the strict control of each layer thickness and composition. The GML nano-film may include two or more types of Quantum Dot material to form Bulk Hetero Junctions or it can be embedded in the organic material (polymer).

GML Nano films have been described so far in only a few publications i.e. "Microchemical Nanofactories", US Patent Publ. 20080108122 (chemical method of building GML Nano); "Nanophotovoltaic Device with Improved Quantum Efficiency", US Patent Publ. 2008142075 2008.(mine); "Energy transfer between quantum dots of different sizes for quantum dot solar cells", 34th PV Spec.Conf., 2009 (Stanford research).

GML Nano films applications for PhotoVoltaics

Assembly of Quantum Dot layers can be designed to efficiently absorb the most of the Sun spectrum (0.3-2.0+ eV) by size and composition tuning. Specifically, one type of Quantum Dots can be selected from the low band-gap material (i.e. PbSe, InAs, Ge, others) to be able to absorb InfraRead part of the spectrum, and by tuning the QDs' sizes Quantum Dots made from the same material will absorb "green/yellow" part. The other Quantum Dots may have a wider band gap to absorb the "blue/UV" part of Spectrum. Due to the Quantum Confinement light absorption in Quantum Dot layers is very strong so the entire Sun spectrum can be absorbed within several tens to a hundred of nanometers.

Quantum Dots generally exhibit Multi Exciton Generation (MEG) phenomena, i.e. generation of more than one electron-hole pair by a single high-energy photon. GML Nano-films, containing low band gap QD's are expected to exhibit and utilize this phenomena, at least in some portion of the film thus enhancing Power Conversion Efficiency of GML Nano-film solar cell.

Size gradient in the GML Nano film creates corresponding gradient of the electro-chemical potential, which is equivalent to generation of high built-in Electric field in the film, which enhances transport of electrons and holes thus improving internal quantum efficiency (IQE) and photo current.

GML Nano films can exhibit phenomena of light trapping and photon re-emission, which additionally enhances IQE.

In case the efficient method of building GML Nano film is available the efficient PV structure can be formed that will provide the highest possible Power Conversion Efficiency.

PV expectations and main challenges

Theoretically, assuming a perfect transport (IQE), Multi Exciton Generation and perfect light trapping/photon re-emission and max possible Voc, the PCE can reach 65+% (still below the thermodynamic limit of about 86%). It is, however, a very challenging goal (see e.g. "Prospects of Nanostructure-Based Solar Cells...", Int. Journ. Of Photoenergy, 2009, id 154059).

One challenge here is to design a GML Nano structure in such precise and well-controlled way that allows for successful utilizing most or all of the above advantages of QD systems. But, even if the "smart" design of an efficient GML Nano structure had been available it would be unclear as to how to build such a structure in a well controlled, reliable, inexpensive and production-worthy way.

This represent another big challenge as most of the known methods of building nanostructured material are either unable to form a GML Nano structure (spin-coating, generally all solution coating methods) or are very expensive with low throughput and difficulties to be transferred to a full-scale production environment (Atomic Layer Deposition (ALD), Langmuir-Blodget or Microchemical method of US 20080108122).

####

For more information, please click here

Contacts:
Dr. Boris Gilman

Copyright © Coolsol R&C

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

GLOBALFOUNDRIES Announces Availability of 45nm RF SOI to Advance 5G Mobile Communications: Optimized RF features deliver high-performance solutions for mmWave beam forming applications in 5G smartphones and base stations February 22nd, 2017

EmTech Asia breaks new barriers with potential applications of space exploration with NASA and MIT February 22nd, 2017

JPK selects compact tensile stage from Deben for their NanoWizardŽ AFM platform to broaden capabilities for materials characterisation February 22nd, 2017

Molecular phenomenon discovered by advanced NMR facility: Cutting edge technology has shown a molecule self-assembling into different forms when passing between solution state to solid state, and back again - a curious phenomenon in science - says research by the University of Wa February 22nd, 2017

Energy

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

In-cell molecular sieve from protein crystal February 14th, 2017

NREL research pinpoints promise of polycrystalline perovskites February 8th, 2017

Quantum Dots/Rods

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Carbon dots dash toward 'green' recycling role: Rice scientists, colleagues use doped graphene quantum dots to reduce carbon dioxide to fuel December 18th, 2016

Two electrons go on a quantum walk and end up in a qudit: Russian scientists find a way to reliably connect quantum elements December 13th, 2016

Trickling electrons: Close to absolute zero, the particles exhibit their quantum nature November 10th, 2016

Solar/Photovoltaic

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

Material can turn sunlight, heat and movement into electricity -- all at once: Extracting energy from multiple sources could help power wearable technology February 9th, 2017

NREL research pinpoints promise of polycrystalline perovskites February 8th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project