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These nanoparticle DSSCs rely on trap-limited diffusion through the semiconductor nanoparticles for the electron transport.
This limits the device efficiency since it is a slow transport mechanism. Recombination is more likely to occur at longer wavelengths of radiation. It has been proven that there is an increase in the efficiency of DSSC, if the sintered nanoparticle electrode is replaced by a specially designed electrode possessing an exotic 'nanoplant-like' morphology.
F top contact, striking the dye on the surface of the TiO2. Photons striking the dye with enough energy to be absorbed create an excited state of the dye, from which an electron can be "injected" directly into the conduction band of the TiO2.
From there it moves by diffusion as a result of an electron concentration gradient to the clear anode on top. Meanwhile, the dye molecule has lost an electron and the molecule will decompose if another electron is not provided.
The dye strips one from iodide in electrolyte below the TiO2, oxidizing it into triiodide. This reaction occurs quite quickly compared to the time that it takes for the injected electron to recombine with the oxidized dye molecule, preventing this recombination reaction that would effectively short-circuit the solar cell.
The triiodide then recovers its missing electron by mechanically diffusing to the bottom of the cell, where the counter electrode re-introduces the electrons after flowing through the external circuit. Solar conversion efficiency Several important measures are used to characterize solar cells.
The most obvious is the total amount of electrical power produced for a given amount of solar power shining on the cell. Expressed as a percentage, this is known as the solar conversion efficiency. Electrical power is the product of current and voltage, so the maximum values for these measurements are important as well, Jsc and Voc respectively.
Finally, in order to understand the underlying physics, the "quantum efficiency" is used to compare the chance that one photon of a particular energy will create one electron.
In quantum efficiency terms, DSSCs are extremely efficient. Due to their "depth" in the nanostructure there is a very high chance that a photon will be absorbed, and the dyes are very effective at converting them to electrons.
Most of the small losses that do exist in DSSC's are due to conduction losses in the TiO2 and the clear electrode, or optical losses in the front electrode.
The quantum efficiency of traditional designs vary, depending on their thickness, but are about the same as the DSSC. In theory, the maximum voltage generated by such a cell is simply the difference between the quasi- Fermi level of the TiO2 and the redox potential of the electrolyte, about 0.
That is, if an illuminated DSSC is connected to a voltmeter in an "open circuit", it would read about 0. This is a fairly small difference, so real-world differences are dominated by current production, Jsc.
Although the dye is highly efficient at converting absorbed photons into free electrons in the TiO2, only photons absorbed by the dye ultimately produce current. The rate of photon absorption depends upon the absorption spectrum of the sensitized TiO2 layer and upon the solar flux spectrum.
The overlap between these two spectra determines the maximum possible photocurrent. Typically used dye molecules generally have poorer absorption in the red part of the spectrum compared to silicon, which means that fewer of the photons in sunlight are usable for current generation.
In air infiltration of the commonly-used amorphous Spiro-MeOTAD layer was identified as the primary cause of the degradation, rather than oxidation. The damage could be avoided by the addition of an appropriate barrier.
This makes DSSCs attractive as a replacement for existing technologies in "low density" applications like rooftop solar collectors, where the mechanical robustness and light weight of the glass-less collector is a major advantage.
They may not be as attractive for large-scale deployments where higher-cost higher-efficiency cells are more viable, but even small increases in the DSSC conversion efficiency might make them suitable for some of these roles as well.
There is another area where DSSCs are particularly attractive. The process of injecting an electron directly into the TiO2 is qualitatively different from that occurring in a traditional cell, where the electron is "promoted" within the original crystal.
In theory, given low rates of production, the high-energy electron in the silicon could re-combine with its own hole, giving off a photon or other form of energy and resulting in no current being generated.
Although this particular case may not be common, it is fairly easy for an electron generated in another molecule to hit a hole left behind in a previous photoexcitation.
Although it is energetically possible for the electron to recombine back into the dye, the rate at which this occurs is quite slow compared to the rate that the dye regains an electron from the surrounding electrolyte.
Recombination directly from the TiO2 to species in the electrolyte is also possible although, again, for optimized devices this reaction is rather slow.
As a result of these favorable "differential kinetics", DSSCs work even in low-light conditions.A dye-sensitized solar cell (DSSC, DSC, DYSC or Grätzel cell) is a low-cost solar cell belonging to the group of thin film solar cells. It is based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system.
Organic–inorganic perovskite solar cells have recently emerged at the forefront of photovoltaics research. Power conversion efficiencies have experienced an unprecedented increase to reported values exceeding 19% within just four years.
With the focus mainly on efficiency, the aspect of stability has so far not been thoroughly . Dye sensitized solar cells (DSC) are one of the most promising types of solar cells for next generation of solar cell technology that has power conversion efficiency as high as 12% (Nazeeruddin et al., ).
學(經)歷: 中國文化大學-觀光休閒事業管理所 碩士 元智大學博士班(進修中): 學術專長: 中餐烹飪、服務品質管理: 專業證照: 行政院勞委會 乙級證照-中餐烹調 行政院勞委會 丙級證照-中餐烹調 行政院勞委會中餐烹調乙丙級術科監評委員 行政院勞委會中餐烹調乙丙級學術科 . Improving Dye-Sensitized Solar Cell Efficiency by Modification of Electrode Surface Charge.
David Riehm. Abstract: Dye-sensitized solar cells (DSSCs) are considered a promising future source of low-cost solar power.
At present, however, the most efficient DSSC . - Batteries and Energy Storage - Fuel Cells - Electrochemical Capacitors & Supercapcitors - Solar Energy Conversion and Photoelectrochemistry - Electronic .