
Nanocrystal solar cells are
solar cell
A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect. s based on a
substrate
Substrate may refer to:
Physical layers
*Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
** Substrate (aquatic environment), the earthy material that exi ...
with a
coating
A coating is a covering that is applied to the surface of an object, or substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. powder coatings.
Paints ...
of nanocrystals. The nanocrystals are typically based on
silicon
Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...
,
CdTe or
CIGS and the substrates are generally silicon or various organic conductors.
Quantum dot solar cell
A quantum dot solar cell (QDSC) is a solar cell design that uses quantum dots as the captivating photovoltaic material. It attempts to replace bulk materials such as silicon, copper indium gallium selenide ( CIGS) or cadmium telluride ( CdTe). ...
s are a variant of this approach which take advantage of
quantum mechanical
Quantum mechanics is the fundamental physical theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is the foundation of a ...
effects to extract further performance.
Dye-sensitized solar cell
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 '' photoelectr ...
s are another related approach, but in this case the nano-structuring is a part of the substrate.
Previous fabrication methods relied on expensive
molecular beam epitaxy
Molecular-beam epitaxy (MBE) is an epitaxy method for thin-film deposition of single crystals. MBE is widely used in the manufacture of semiconductor devices, including transistors. MBE is used to make diodes and MOSFETs (MOS field-effect transis ...
processes, but colloidal synthesis allows for cheaper manufacturing. A thin film of nanocrystals is obtained by a process known as "
spin-coating". This involves placing an amount of the quantum dot solution onto a flat substrate, which is then rotated very quickly. The solution spreads out uniformly, and the substrate is spun until the required thickness is achieved.
Quantum dot based photovoltaic cells based on dye-sensitized colloidal
TiO2 films were investigated in 1991
and were found to exhibit promising efficiency of converting incident light energy to electrical energy, and to be incredibly encouraging due to the low cost of materials used. A single-nanocrystal (channel) architecture in which an array of single particles between the electrodes, each separated by ~1 exciton diffusion length, was proposed to improve the device efficiency and research on this type of solar cell is being conducted by groups at Stanford, Berkeley and the University of Tokyo.
Although research is still in its infancy, nanocrystal photovoltaics may offer advantages such as flexibility (quantum dot-polymer composite photovoltaics)
lower costs, clean power generation and an efficiency of 65%, compared to around 20 to 25% for first-generation,
crystalline silicon
Crystalline silicon or (c-Si) is the crystalline forms of silicon, either polycrystalline silicon (poly-Si, consisting of small crystals), or monocrystalline silicon (mono-Si, a continuous crystal). Crystalline silicon is the dominant semicon ...
-based photovoltaics in the future.
It is argued that many measurements of the efficiency of the nanocrystal solar cell are incorrect and that nanocrystal solar cells are not suitable for large scale manufacturing.
[
]
Recent research has experimented with
lead selenide
Lead selenide (PbSe), or lead(II) selenide, a selenide of lead, is a semiconductor material. It forms cubic crystals of the NaCl structure; it has a direct bandgap of 0.27 eV at room temperature. (Note that incorrectly identifies PbSe and ...
(PbSe) semiconductor, as well as with
cadmium telluride photovoltaics
Cadmium telluride (CdTe) photovoltaics is a photovoltaic (PV) technology based on the use of cadmium telluride in a thin semiconductor material, semiconductor layer designed to absorb and convert sunlight into electricity. Cadmium telluride PV ...
(CdTe), which has already been well established in the production of second-generation
thin film solar cells. Other materials are being researched as well.
Other third generation solar cells
*
Photoelectrochemical cell
A "photoelectrochemical cell" is one of two distinct classes of device. The first produces electrical energy similarly to a dye-sensitized photovoltaic cell, which meets the standard definition of a photovoltaic cell. The second is a photoelect ...
*
Polymer solar cell
*
Perovskite solar cell
See also
*
Nanocrystalline silicon
*
Nanoparticle
A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...
References
External links
*Science News Online
Quantum-Dots Leap: Tapping tiny crystals' inexplicable light-harvesting talent June 3, 2006.
*
InformationWeek
''InformationWeek'' is a digital magazine which conducts corresponding face-to-face events, virtual events, and research. It is headquartered in San Francisco, California
California () is a U.S. state, state in the Western United State ...
Nanocrystal Discovery Has Solar Cell Potential January 6, 2006.
*
Berkeley Lab
Lawrence Berkeley National Laboratory (LBNL, Berkeley Lab) is a federally funded research and development center in the hills of Berkeley, California, United States. Established in 1931 by the University of California (UC), the laboratory is spo ...
Berkeley Lab Air-stable Inorganic Nanocrystal Solar Cells Processed from Solution 2005.
*ScienceDaily
October 23, 2005.
{{Photovoltaics
Solar cells
Nanomaterials
Quantum electronics