Energy Harvesting and Nanotechnology

Topics: Solar cell, Band gap, Quantum dot Pages: 6 (1846 words) Published: November 3, 2011
Energy Harvesting and Nanotechnology| April 28
Energy harvesting generators are attractive as unlimited replacements for batteries in electronic devices and have been the focus of new researches for past years. This paper reviews the principles behind this technology and their integration to harvest energy. Also proposes a greener alternative for the production of quantum dots before the integration to new technologies.| Nanowires and Quantum Dots|

Energy Harvesting with Nanowires and Quantum Dots
Harvesting energy is the core of our modern human existence. We need to power our cars, homes, and personal electronics. T o power our technology we need energy. Most electrical energy is harvested in one of two ways. These ways are mechanically harvested or harvested from solar power. Mechanically harvested energy needs moving parts, for example, to turn a generator. Solar energy can be harvested through solar cells via the photoelectric effect. As technology becomes smaller and more compact, power conversion technology needs to also adapt to this changes. Nanotechnology has shown great promise to become the power generator for future nanotechnology.1 That is the purpose of this paper to show how this technology works and is integrated to the production of energy.

Nanowires have a diameter in between 20 nm and 100 nm. They can be made from many types of material, however most research is being done on silicon nanowires1-2 3 4 5 6 ; carbon and CdS/CdTe7 nanowires also are being researched. These nanowires can convert solar energy into electrical energy with enough efficiency to power small devices. This technology can create self sufficient nanotechnologies that do not need batteries or need to be connected to a power source. This new technology will be completely different to the macro-technology we have today, were we have to change out batteries or plug them into a wall. Self-sustaining technology is very green, because they do not need a non-renewable outside energy sources.

Quantum dots are being researched as a viable alternative to silicon based solar cells. Quantum dots are small particles, or “nanoparticles”, of a semiconductor material, most common chalcogenides (selenides or sulfides) of metals like cadmium or zinc (CdSe or ZnS), which are usually from 2 to 10 nanometers in diameter. Because of their size, quantum dots display unique optical and electrical properties that are different in character to those of the corresponding bulk material. The most relevant of these is the emission of photons under excitation, which are visible to the human eye as light. Moreover, Quantum dots can be tuned to certain wavelengths based on their size and are able to produce more than one electron per absorbed photon. These molecules are generally made out of CdSe and are cheap, their synthesis is relatively green, and they have great stability over many years. They do not bleach like other dyes and their efficiency does not fade nearly as quickly as normal dyes. 7

Nanowires and quantum dots have become very interesting topics in chemical research. They have potential to start a new wave of technology and may be the future power source of almost every technology. This article is about how scientists can harvest solar power on a nanoscale, with quantum dot technology showing much promise as a green solution. Solar Power.

Today, solar power is harvested by large photovoltaic cells (a solid state electrical device that converts the energy of sunlight directly into electricity) that are made of crystalline silicon; the generation of electricity from the sun was a landmark in Green Chemistry. However, these large panels are bulky and expensive. Silicon nanowires use the same mechanism for power generation, but are smaller and more portable. The coaxial silicon nanowires operate by using coaxial shells selectively doped to absorb photons and produce electrons. 1,3 Coaxial silicon nanowires have 2...
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