Energy Harvesting and Nanotechnology

Energy increase and Nano applied science April 28 2011 Energy harvest-tideing generators argon fascinating as unlimited replacements for batteries in electronic machinations and involve been the focus of youngborn researches for noncurrent old age. This paper reviews the principles behind this technology and their consolidation to harvest naught. Also proposes a greener alternate for the wargon of quantum dots before the consolidation to new technologies. Nanowires and Quantum Dots Energy Harvesting with Nanowires and Quantum Dots IntroductionHarvesting push button is the core of our modern gentleman existence. We remove to personnel our cars, homes, and personal electronics. T o baron our technology we need energy. Most galvanising energy is harvested in one of two ways. These ways atomic number 18 mechanic everyy harvested or harvested from solar spot. automatically harvested energy ineluctably moving parts, for example, to binge a generator. Solar energy stub be harvested through solar cells via the photoelectric effect. As technology deforms teenyer and jams compact, power conversion technology needs to also adapt to this increases.Na nonechnology has designaten great bargain to become the power generator for future tense na nonechnology. 1 That is the purpose of this paper to presentation how this technology works and is integrated to the production of energy. Nanowires claim a diameter in between 20 nm and atomic number 6 nm. They target be made from some types of strong, however closely research is world done on ti nanowires1-2 3 4 5 6 nose messdy and CdS/CdTe7 nanowires also atomic number 18 being researched. These nanowires faeces convert solar energy into galvanizing energy with enough competency to power small devices.This technology can hold self sufficient nanotechnologies that do not need batteries or need to be connected to a power quotation. This new technology will be exclusively differe nt to the macro-technology we take in today, were we have to change let on batteries or plug them into a wall. independent technology is really green, because they do not need a non-renewable alfresco energy sources. Quantum dots be being researched as a viable alternative to atomic number 14 base solar cells.Quantum dots ar small particles, or nanoparticles, of a semiconductor square, most common chalcogenides (selenides or sulfides) of alloys deal certificate of deposit or zinc (CdSe or ZnS), which ar usually from 2 to 10 nanometers in diameter. Because of their size, quantum dots display unique optic and electrical properties that atomic number 18 different in showcase to those of the corresponding bulk material. The most applicable of these is the emission of photons under excitation, which atomic number 18 indubitable to the human eye as light.Moreover, Quantum dots can be tuned to certain wavelengths based on their size and atomic number 18 able to prove more than one electron per absent photon. These molecules be generally made out of CdSe and are cheap, their tax deduction is relatively green, and they have great stability over umteen years. They do not bleach analogous other dyes and their efficiency does not drop dead nearly as quickly as normal dyes. 7 Nanowires and quantum dots have become very interesting topics in chemic research.They have potential to start a new wave of technology and whitethorn be the future power source of almost every technology. This article is close to how scientists can harvest solar power on a nanoscale, with quantum dot technology showing much promise as a green solution. Solar author. 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 coevals of electricity from the sun was a margin in Green Chemistry.However, these large panels are bulky an d expensive. Silicon nanowires use the same mechanism for power generation, barely are smaller and more portable. The concentric silicon nanowires operate by using coaxial shells selectively doped to absorb photons and garden truck electrons. 1,3 Coaxial silicon nanowires have 2 shells and a core, pulp 1 shows the nanowire and a view of the cross section of the nanowire. figure of speech 1. The blue outside shell is the n-type shell, the inward yellow shell is in the i-type shell, and the knock core is the p-type core.The diagram on the accountability shows how the holes (h+), and the photo generated electrons (e-) consort across the nanowire. (Adapted from figure 1 in Nature 2007, 449, 885-889) The outermost shell is crystalline in organize which enables the wire to absorb photons. The semiconductor material construction made this nanowire operate corresponding a diode. Diodes allow current to flow one way but not another. Diodes are very common in household electroni cs and circuits. This means that self-powered circuits can be created from these nanowires. , 3-4 Quantum Dots are able to verbalize triple excitons from one photon through an effect called the duple Exciton Effect. An exciton is an electron and its hole. Quantum dots can be tuned to numerous different wavelengths of light, because the wavelength they absorb is based on the diameter of the dot. The material for quantum dots is more constitute effective than silicon-based solar panels. Theoretical limits for power conversion efficiency are close to 60% 7. This is an amazing efficiency, but thither are some debates about how veritable this efficiency is.There is not much known about quantum dots still, the organic outer layer that is used to separate these particles calculate to have photo-electronic effects as well. conformation 2, shows an experimental power generator utilizing quantum dots and a mechanical piezoelectric generator. Figure 2 This is a power generator that u ses two solar and mechanical means to harvest power. The quantum dots are interlaced in the ZnO nanowires. The solar cell power conversion efficiency of this device was 15. 8%. Unfortunately, the process of qualification reasoned metal quantum dots is not very green.Some processes require high gear temperatures and heavy material loss. Current production methods have seen some LCA assessments of quantum dots. There is a lot of bollix up developed during the production and purification of quantum dots. Mass-by-mass comparison with silicon solar cells, show that quantum dots require far more energy and solvent. However, since only a small total of quantum dots are being used in technology and the long lasting and high efficiency of power generation gives quantum dots a better assessment in all environmental aspects except heavy metal emission. Since rising technologies rapidly change, this assessment could be outdated in six months with a new greener synthesis. Proposal Greene r QDs Cadmiun free quantum dots In umpteen parts of the world thither are legislation that restrict and in some cases ban heavy metals such as Cd in many household appliances such as brightness equipment , Electrical & electronic tools, vaunt telecommunication equipment and entertainment devices. Many reports have shown that compact disc-based QDs were toxic at the tissue and cellular levels when their surfaces are not carefully functionalized. 1, 12 CuInS2 is a direct streak bedspread semiconductor material with a band gap of 1. 45 eV. Thus, by tailor their composition and size, it is possible to fabricate CuInS2 QDs that emit from the visible to near-infrared (NIR) region, with high quantum yield. More importantly, CuInS2 QDs are more suitable for biomedical tomography applications and integration in household devices because the particles are free from toxic elements such as cadmium, lead, mercury.The properties of these nanoparticles are very similar to those of CdS qu antum dots, but the overall efficiency and shifts in spectra are still lower that the ones obtained by cadmium QDs. More research needs to be done to increase the overall properties of this nanoparticles and their integration to electronic devices, but some ideas that are being currently tried are coating CuInS2 with organic materials that enables the particles to be more efficient and increases their luminescence.Currently this QDs are being mass produced for example by Nanoco is a nanotechnology company located in Manchester, United Kingdom that uses a molecular(a) seeding method adapted for other compound semiconductor materials, which have similar optical properties to those of CdSe quantum dots (such as the family of III-V materials), but do not contain heavy metals. So the possibilities for the effectuation of this technology on devices that are in constant contact with humans are infinite, if new alternatives like this are utilise in future designs.Conclusion Self-sustainin g technology is the end goal for these nanogenerators this can lead to a green rotation in technology and reduce the emissions into our atmosphere. Currently, quantum dots are beginning to show amazing properties that whitethorn one day replace batteries and carbon- based energy production. Unfortunately, the current process for the synthesis of quantum dots generates too much solvent waste and uses too much power, but there is research trying to quantify the environmental bear on and reduce it.Since quantum dots are an emerging technology, the production and utilization may drastically change in the coming years and hopefully a strong idiom on low environmental continue will be on the forefront. retardation this technology is being introduced in the solar energy production and medical procedures like targeting cell and biomarkers, giving results that promise a change in the way energy is produced. References 1. Tian, B. Z. Zheng, X. L. Kempa, T. J. Fang, Y. Yu, N. F. Yu, G . H. Huang, J. L. Lieber, C. M. , Coaxial silicon nanowires as solar cells and nanoelectronic power sources.Nature 2007, 449 (7164), 885-U8. 2. Peng, K. Q. Wang, X. Lee, S. T. , Silicon nanowire set forth photoelectrochemical solar cells. utilise Physics letter 2008, 92 (16). 3. Sivakov, V. Andra, G. Gawlik, A. Berger, A. Plentz, J. Falk, F. Christiansen, S. H. , Silicon Nanowire-Based Solar prison cells on Glass Synthesis, Optical Properties, and Cell Parameters. Nano letter 2009, 9 (4), 1549-1554. 4. Tian, B. Kempa, T. J. Lieber, C. M. , Single nanowire photovoltaics. Chemical bon ton Reviews 2009, 38 (1), 16-24. 5. Tsakalakos, L. Balch, J. Fronheiser, J. Korevaar, B. A. Sulima, O. Rand, J. , Silicon nanowire solar cells. Applied Physics Letters 2007, 91 (23). 6. Yang, R. S. Qin, Y. Dai, L. M. Wang, Z. L. , Power generation with laterally packaged piezoelectric fine wires. Nat. Nanotechnol. 2009, 4 (1), 34-39. 7. Lee, M. Yang, R. Li, C. Wang, Z. L. , Nanow ire-Quantum Dot Hybridized Cell for Harvesting Sound and Solar Energies. J. Phys. Chem. Lett. 2010, 1 (19), 2929-2935. 8. Sengul, H Thomas T. , An environmental impact assessment of quantum dot photovoltaics from raw material acquisition through use.Journal of antiseptic Production. 2011, 19, 21-31. 9. 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