Solar cells and materials research by fdjerue7eeu


									Solar cells and materials research
Pyeongchang original | 2010-1-26 17:27 | vote | Read: 25 This recommendation has
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Keywords: solar cells and materials research
Solar energy is inexhaustible renewable human energy. Is also clean energy, not
produce any environmental pollution. Effective use of them in solar; large
photovoltaic solar energy use in recent years is the fastest growing, most dynamic
area of research, is one of the most watched items. To this end, people have developed
a solar cell. Solar cells are mainly based on semiconductor materials, its working
principle is the use of photovoltaic materials absorb light energy of conversion
occurred after the photoelectric response, according to the different materials, solar
cells can be divided into:

1, silicon solar cells;

2 to inorganic salts such as III-V compounds GaAs, CdS, copper indium selenium
compounds such as multi-material cell;

3, Functional Polymer Materials of large solar energy battery;

4, nanocrystalline solar cells. Regardless of what material to produce batteries, solar
cell material on the general requirements are:

①, the band gap semiconductor materials can not be too wide;

②, have a higher photoelectric conversion efficiency of:

③, the material itself does not cause pollution to the environment;

④, material suitable for mass production and materials performance and stability.

Based on the above aspects to consider, is the ideal silicon solar cell material, which is
silicon-based solar cells to the main reason. But with the continuous development of
new materials and related technology to other village-based solar cell materials have
shown more and more attractive prospects. This paper briefly reviews the types of
solar cells and its research status, and discussed the development trend of solar cells.

1, silicon solar cells

1.1 monocrystalline silicon solar cells

Silicon Series Solar Cells, Silicon Solar energy conversion efficiency of the battery
top, the most mature technology. High-performance silicon solar cell is built on
high-quality silicon and related materials into a heat treatment process based on the
processing. Electricity to process silicon now has nearly mature, in the battery
production, is generally used texturing, emitter passivation, area doping technology,
the development of the battery mainly flat groove buried monocrystalline silicon cells
and silicon gate electrode battery. Improve the conversion efficiency depends mainly
on the silicon surface micro-structure of treatment and doping process area. In this
regard, the German Institute for Solar Energy Systems Fort 夫朗霍费费莱 maintains
the world's advanced level. The Institute will use lithography photography
texture of the surface of the battery, made pyramid. And the surface to a 13nm, thick
oxide passivation layer and the combination of two anti-reflection coating, plating
process by improving the gate to increase the ratio of the width and height: the above
conversion efficiency of the battery obtained more than 23 %, is the largest value of
up to 23.3%. Kyocera Corporation prepared a large area (225cm2) single-crystal solar
cell power conversion efficiency of 19.44%, China Beijing Solar Energy Research
Institute is also active and efficient crystalline silicon solar cell research and
development, the development of highly efficient silicon solar cell surface (2cm ×
2cm ) conversion efficiency of 19.79%, groove buried gate electrode of crystalline
silicon cells (5cm × 5cm) conversion efficiency of 8.6%.

Monocrystalline silicon solar cell conversion efficiency is undoubtedly the highest in
the large-scale applications and industrial production is still dominant, but due to Dan
Jinggui material prices and the corresponding complicated process affects the battery,
causing the high silicon cost price home no less, to a significant reduction in the cost
is very difficult. To save high-quality materials, look for silicon solar cell replacement
product, and now developed a thin film solar power

Pool, in which polycrystalline silicon thin film solar cells and amorphous silicon thin
film solar cells are typical examples.

1.2 polycrystalline silicon thin film solar cells

Crystal silicon solar cells are usually in the thickness of 350 ~ 450μm made of
high-quality silicon, such silicon Czochralski or cast from the cutting of silicon ingots
made. Therefore, the actual consumption of silicon materials for more. To save
material, people from the mid-70s began low-cost polycrystalline silicon thin film
deposited on the substrate, but the growth of silicon film grain size, not made of
valuable solar cells. In order to obtain large grain of film, it has not stopped research
and made a lot of ways. Preparation of polycrystalline silicon thin film over the
current use of chemical vapor deposition, including low pressure chemical vapor
deposition (LPCVD) and plasma enhanced chemical vapor deposition (PECVD)
process. In addition, the liquid phase epitaxy method (LPPE) and sputtering
deposition can also be used to prepare polycrystalline silicon thin film batteries.

Chemical vapor deposition mainly SiH2Cl2, SiHCl3, Sicl4 or SiH4, as the reactive
gas atmosphere in a protective reaction of silicon atoms and deposition in the heated
substrate, the substrate material generally used in the Si, SiO2, Si3N4, etc.. But the
study found that non-silicon substrates is difficult to form larger grains, and easy to
form a gap between grains. Way to solve this problem is to first substrate using
LPCVD Shen Chi in a thin layer of amorphous silicon layer, then this layer of
amorphous silicon layer annealing, have larger grains, and then seed at this level thick
polysilicon thin film deposition, therefore, re-crystallization is undoubtedly a very
important aspect of the technology currently used mainly in the solid phase
crystallization and zone melting recrystallization. In addition to polycrystalline silicon
thin film cells using recrystallization process, the other with almost all the technical
preparation of monocrystalline silicon solar cells, solar cells obtained by this
conversion efficiency has improved significantly. Solar Energy Research Institute in
Germany by German Freiburg District Museum recrystallization in FZ Si substrates
obtained polysilicon cell efficiency is 19%, the Japanese Mitsubishi company
prepared to use the battery efficiency of 16.42%.

Liquid phase epitaxy (LPE) method works by melting the silicon in the matrix, the
lower temperature precipitation of silicon film. U.S. Astropower company prepared
by LPE cell efficiency of 12.2%. The development of China's
Optoelectronic Technology Center Chen Zheliang by liquid phase epitaxy in the
growth of metallurgical grade silicon crystal on silicon, and designed a similar
crystalline silicon thin film solar cells a new type of solar cell, called
"silicon particles" solar cells But the performance reports have
yet to see.

Polysilicon thin film silicon cells used as less than silicon, and inefficient recession,
and may low-cost substrate materials in the preparation, the cost is far lower than the
silicon solar cell, while more efficient than amorphous silicon thin film battery,
therefore, polycrystalline silicon thin film solar cells will soon dominate the local

1.3 amorphous silicon thin film solar cells

Development of solar cells are two key question is: to improve efficiency and reduce
costs. As the amorphous silicon thin film solar cells and low cost, easy mass
production, the general attention by people and the rapid development, Qishizaozai
the early 70's, Carlson Deng has already begun on the development of the
Fei Jinggui battery Gongzuo, Jinji In its development work has been rapid
development, many of the world had

Companies in the production of the kinds of batteries.

Although amorphous silicon material as a solar battery is a good material, but because
of its optical band gap of 1.7eV, makes the material itself on the solar radiation
spectrum is not sensitive to long wavelength region, such an action would limit the
amorphous silicon solar cells conversion efficiency. In addition, the optical efficiency
will continue as the illumination time and decay, the so-called S 1 W of light induced
degradation effect, making stable cell performance. Solve these problems is the
preparation of this track tandem solar cells, tandem solar cells prepared by the p, i, n
single-junction solar cell layer re-deposited one or more sub-battery system obtained
Pin. Improve the conversion efficiency of tandem solar cells to address the stability of
single-junction solar cell is not the key question:

①, which the band gap of the material in different branches units together to improve
the spectral response range;

②, the top cell i layer thin, light produced little change in the electric field strength to
ensure the i layer of light-induced carriers out;

③, produced by the end of the battery carrier is about half the single-cell, light
induced degradation effect decreased;

④, tandem solar cells is the son of batteries together in series.

Preparation of amorphous silicon thin film solar cells there are many ways, including
reactive sputtering, PECVD method, LPCVD law, the reaction feed gas for the H2
diluted SiH4, mainly glass and stainless steel substrate film made of amorphous
silicon film through the various cell processes, respectively obtained by
single-junction tandem solar cells and batteries. Amorphous silicon solar cells
currently achieve two major advances: first, the three tandem structure amorphous
silicon solar cell conversion efficiency of 13%, setting a new record; the second and
third tandem solar cell annual production capacity of 5MW. United Solar Corporation
(VSSC) obtained the highest single-junction solar cell conversion efficiency of 9.3%,
three three-band gap tandem solar cell conversion efficiency of 13% maximum. The
maximum conversion efficiency is in the small area (0.25cm2) battery made. Some
literature reported that single-junction amorphous silicon solar cell conversion
efficiency of more than 12.5%, Japan's Academia Sinica, using a series of
new measures obtained in the amorphous silicon cell efficiency of 13.2%. Domestic
battery, especially on the amorphous silicon thin film tandem solar cells have not been
studied, Nankai University, Geng Xinhua and other industrial materials used to
prepare the aluminum back electrode area 20X20cm2, conversion efficiency was
8.28% of the a-Si / a-Si tandem solar cells.

Amorphous silicon solar cells with high conversion efficiency and low cost and light
weight, has great potential. But the stability is not high because of its direct impact on
its practical application. If we can solve the stability problems and further improve the
conversion rate of the problem, then the sun can be amorphous silicon solar battery is
undoubtedly one of the major development of products.

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