View source for Physics:Gradient multilayer nanofilm

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'''Gradient multilayer (GML) [[Physics:Nanomaterials|nanofilm]]''' is an assembly of [[Physics:Quantum dot|quantum dot]] layers with a built-in [[Gradient|gradient]] of nanoparticle size, composition or density.

Properties of such [[Physics:Nanostructure|nanostructure]] are finding its applications in design of [[Physics:Solar cell|solar cell]]s<ref>{{cite conference |book-title=2009 34th IEEE Photovoltaic Specialists Conference (PVSC) |doi=10.1109/PVSC.2009.5411731 |title=Energy transfer between quantum dots of different sizes for quantum dot solar cells |year=2009 |last1=Holm |first1=Timothy P. |last2=Cheng Chieh Chao |last3=Prinz |first3=Fritz B. |isbn=978-1-4244-2949-3 |page=85}}</ref><ref>Reddy, Damoder and Gilman, Boris [http://www.freepatentsonline.com/y2008/0142075.html Nanophotovoltaic Device with Improved Quantum Efficiency]. US Patent Application 20080142075. Freepatentsonline.com. Retrieved on 2012-05-22.</ref><ref>[http://www.freepatentsonline.com/y2009/0255580.html Quantum dot solar cell with quantum dot bandgap gradients]. Freepatentsonline.com. Retrieved on 2012-05-22.</ref> and [[Engineering:Energy storage|energy storage]] devices.<ref>[http://www.freepatentsonline.com/y2010/0183919.html Quantum dot ultracapacitor and electron battery]. Freepatentsonline.com. Retrieved on 2012-05-22.</ref>

The GML nanostructure can be embedded in the organic material ([[Chemistry:Polymer|polymer]]), or can include quantum dots made of two or more types of material. 
[[Image:GMLnanofilm.png|thumb|center|300px|Schema of GML nanofilm]]

'''Photovoltaic applications'''

The GML nanofilm only 100 nanometers thick can absorb the entire Sun spectrum (0.3–2.0+ eV). At the same time, gradient of the quantum dots size can create a gradient of the electrochemical potential, acting as an equivalent of built-in [[Physics:Electric field|electric field]] inside a nanofilm. This enhances transport of [[Physics:Electron|electron]]s and [[Physics:Electron hole|holes]], and improves internal quantum efficiency (IQE) and [[Physics:Photocurrent|photocurrent]].

'''Manufacturing'''

The industrial manufacturing of GML nanofilms represents a challenge. Traditional methods of building nanostructured materials (like [[Physics:Spin coating|spin coating]]) can't form GML nanostructures, while more effective methods like Atomic Layer Deposition (ALD) or Langmuir-Blodget "microchemical" method.<ref>[http://www.freepatentsonline.com/y2008/0108122.html Microchemical nanofactories]. Freepatentsonline.com. Retrieved on 2012-05-22.</ref> are expensive.

== See also ==

==References==
{{reflist}}

== External links ==
* [http://www.nanotech-now.com/news.cgi?story_id=40310 Gradient Multi-Layer Nano-films for Photovoltaic and other applications]
* [http://www.nature.com/nphoton/jour]

[[Category:Nanomaterials]]

{{Sourceattribution|Gradient multilayer nanofilm}}