these structure are based on semiconductor nanowires that most be interconnected in somehow to the get contacted and trabnfer electrons , but there are many deactrivating processes that can occurr at this level and the close proximity the many wires are .
there is a big chance to have lots of Ohmkic losses, heat dissipation , recombination from neighboring wires, Hall effects , tunneling and so on
What could you comment about other effects ?=
and what could you comment about avoid some of these drawbacking effects by the designd oand manufacturing of the device?
best regards
Dr Pit Navarro
The main challenges which require substantial efforts:
- growth of phase pure NW
-synthesize large- scale assembly.
-uniformity of the synthesized NW including morphology, structure and doping level
- efficiency and organization of individual NW elements
The typical efficiency limit - the so-called "Shockley-Queisser Limit" - is a limit, which for many years has been a landmark for solar cells efficiency among researchers, but now it seems that it may be increased.
It's exciting as a researcher to move the theoretical limits, as we know. Although it does not sound like much, that the limit is moved by only a few percent, it will have a major impact on the development of solar cells, exploitation of nanowire solar rays and perhaps the extraction of energy at international level. However, it will take some years years before production of solar cells consisting of nanowires becomes a reality, says Peter Krogstrup who just completed his PhD at the Niels Bohr Institute, University of Copenhagen.
Current solar cell technologies are dominated by silicon. Limited primarily by silicon's inherent properties, these solar cells convert only 15–20% of solar energy into electricity. Solar cells made from III-V compound semiconductors (materials that contain group III and group V elements) have much higher efficiencies, due to their better optical (absorption) and electrical (charge mobility) properties. Furthermore, with different III-V materials on the same device, researchers can produce multiple junctions or heterostructures to cover a broader range of the solar spectrum. In these devices, researchers have demonstrated efficiencies of over 40% under concentrated solar energy.1
The additional benefits afforded by nanotechnology may further enhance solar cell performance. Nanowire research has emerged as a quickly growing field. Much excitement stems from the unique electronic and optical properties of semiconductor nanowires. Nanowires of a particular substance may behave quite unlike much larger ‘bulk’ samples of the same material. Nanowires are of great interest in photovoltaics because of their large surface area, high aspect ratio (long and thin), intrinsic antireflection effect (which increases light absorption), and ability to direct light absorption with specifically designed arrays.
(1) to make a large array of identical nanowires
(2) to make good contact to all the nanowires
(3) to control the doping, if required. Approaches requiring no doping is perhaps more feasible (e.g., Z. Wu, J. Mater. Chem., 2011, 21, 6020)
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