CN104851931A - Cadmium telluride thin-film solar cell with gradient structure and manufacture method thereof - Google Patents

Cadmium telluride thin-film solar cell with gradient structure and manufacture method thereof Download PDF

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CN104851931A
CN104851931A CN201510174737.XA CN201510174737A CN104851931A CN 104851931 A CN104851931 A CN 104851931A CN 201510174737 A CN201510174737 A CN 201510174737A CN 104851931 A CN104851931 A CN 104851931A
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cadmium telluride
cdte
layer
energy gap
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CN104851931B (en
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李廷凯
李晴风
钟真
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HUNAN GONGCHUANG GROUP CO Ltd
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    • HELECTRICITY
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    • H01L31/00Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/065Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the graded gap type
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
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    • H01L31/0296Inorganic materials including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
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    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract

The invention discloses a cadmium telluride thin-film solar cell with gradient structure and a manufacture method thereof. The cadmium telluride thin-film solar cell comprises a pn junction formed by a CdTe absorbing layer and a CdS window layer. The CdTe absorbing layer of the pn junction of the cadmium telluride thin-film solar cell is a Cd<x>Te<Y> multilayer gradient structure with an energy gap gradient, wherein x is more than or equal to 0 but is less than or equal to 1 and y is more than or equal to 0 but is less than or equal to 1. The gradient structure has a relatively wide energy spectrum range, may separate and capture ionized electrons, and generateS heavy current under the excitation of the sun so as to improve the efficiency of the thin-film solar cell. The gradient structure prevents abnormal growth of crystal grains and generation of holes and cracks and produces a compact high-quality film with uniform crystal grain sizes and matched energy gaps. Further, the gradient structure is beneficial to the full absorption of sunlight so as to further improve the efficiency of the cadmium telluride thin-film solar cell.

Description

There is cadmium telluride diaphragm solar battery and the manufacture method thereof of gradient-structure
Technical field
The present invention relates to solar cell and thin-film solar cells and the manufacture method thereof with gradient-structure, particularly there is cadmium telluride diaphragm solar battery structure and the manufacture method thereof of gradient-structure.
Background technology
After French scientist AE.Becquerel found opto-electronic conversion phenomenon in 1839,1883 first be that the solar cell of substrate is born with semiconductor selenium.Nineteen forty-six Russell obtains the patent (US.2,402,662) of first solar cell, and its photoelectric conversion efficiency is only 1%.Until 1954, the research of Bell Laboratory has just found that the silica-base material adulterated has high photoelectric conversion efficiency.This research is laid a good foundation for modern sun energy battery industry.In 1958, Haffman Utilities Electric Co. of the U.S. was that the satellite of the U.S. has loaded onto first piece of solar panel, and its photoelectric conversion efficiency is about 6%.From then on, the solar cell research of monocrystalline silicon and polycrystalline silicon substrate and production have had and have developed fast, the output of solar cell in 2006 has reached 2000 megawatts, the photoelectric conversion efficiency of monocrystaline silicon solar cell reaches 24.7%, commercial product reaches 22.7%, the photoelectric conversion efficiency of polysilicon solar cell reaches 20.3%, and commercial product reaches 15.3%.
On the other hand, the Zhores Alferov of the Soviet Union in 1970 have developed high efficiency III-V race's solar cell of first GaAs base.Owing to preparing the key technology MOCVD (metal organic chemical vapor deposition) of III-V race's thin-film material until about 1980 are are just successfully researched and developed, the applied solar energy Battery Company of the U.S. was successfully applied this technology and is prepared III-V race's solar cell that photoelectric conversion efficiency is the GaAs base of 17% in 1988.Thereafter, take GaAs the doping techniques of III-V race's material of substrate, the technology of preparing of plural serial stage solar cell obtains research and development widely, its photoelectric conversion efficiency reached 19% in 1993, within 2000, reach 24%, within 2002, reach 26%, within 2005, reach 28%, within 2007, reach 30%.2007, large III-V solar cell company of race Emcore and SpectroLab of the U.S. two produces high efficiency III-V race solar energy commercial product, its photoelectric conversion rate reaches 38%, this two company occupies 95% of III-V race's solar cell market, the whole world, nearest American National Energy Research Institute announces, they successfully have developed its photoelectric conversion efficiency up to 50% III-V race's solar cell of plural serial stage.Because the substrate of this kind of solar cell is expensive, instrument and supplies cost is high, is mainly used in the fields such as Aeronautics and Astronautics, national defence and military project.
External solar cell research and production, roughly can be divided into three phases, namely have three generations's solar cell.
First generation solar cell is for representative substantially with the solar cell of monocrystalline silicon and the silica-based single constituent element of polycrystalline.Only pay attention to improve photoelectric conversion efficiency and large-scale production, there is high energy consumption, labour intensive, the problem such as unfriendly and high cost to environment, its price producing electricity is about 2 of coal electricity ~3 times; Until 2014, the output of first generation solar cell still accounts for the 80-90% of global solar battery total amount.
Second generation solar cell is thin-film solar cells, is the new technology grown up in recent years, and it pays attention to reduce the energy consumption in production process and process costs, and brainstrust is called green photovoltaic industry.Compare with polysilicon solar cell with monocrystalline silicon, the consumption of its film HIGH-PURITY SILICON is its 1%, simultaneously, low temperature (about about 200 DEG C) plasma enhanced chemical vapor deposition deposition technique, electroplating technology, printing technology is extensively studied and is applied to the production of thin-film solar cells.Owing to adopting glass, the stainless steel thin slice of low cost, macromolecule substrate, as baseplate material and low temperature process, greatly reduces production cost, and is conducive to large-scale production.The material of the thin-film solar cells of success research and development is at present: CdTe, and its photoelectric conversion efficiency is 16.5%, and commercial product is about about 12%; CulnGaSe (CIGS), its photoelectric conversion efficiency is 19.5%, and commercial product is about 12%; Amorphous silicon and microcrystal silicon, its photoelectric conversion efficiency is 8.3 ~ 15%, and commercial product is 7 ~ 12%, in recent years, due to the research and development of the thin-film transistor of LCD TV, amorphous silicon and microcrystalline silicon film technology have had significant progress, and are applied to silicon-based film solar cells.Focus around thin-film solar cells research is, exploitation is efficient, low cost, long-life photovoltaic solar cell.They should have following feature: low cost, high efficiency, long-life, material source are abundant, nontoxic, the relatively more good amorphous silicon thin-film solar cell of scientists.The thin-film solar cells accounting for lion's share is at present non-crystal silicon solar cell, is generally pin structure battery, and Window layer is the P-type non-crystalline silicon of boron-doping, then deposits the unadulterated i layer of one deck, then deposits the N-type amorphous silicon that one deck mixes phosphorus, and plated electrode.Brainstrust is estimated, because thin-film solar cells has low cost, high efficiency, the ability of large-scale production, at 10 ~ 15 years of future, thin-film solar cells will become the main product of global solar battery.
Amorphous silicon battery generally adopts PECVD (Plasma Enhanced Chemical Vapor Deposition-plasma enhanced chemical vapor deposition) method that the gases such as high purity silane are decomposed and deposits.This kind of manufacture craft, can complete in multiple vacuum deposition chamber continuously aborning, to realize producing in enormous quantities.Due to deposition decomposition temperature low, can on glass, corrosion resistant plate, ceramic wafer, flexible plastic sheet deposit film, be easy to large areaization produce, cost is lower.The structure of the amorphous silicon based solar battery prepared on a glass substrate is: Glass/TCO/p-a-SiC/i-a-Si/n-a-Si/TCO, and the structure of the amorphous silicon based solar battery prepared at the bottom of stainless steel lining is: SS/ZnO/n-a-Si/i-a-Si/p-na-Si/ITO.
Internationally recognized amorphous silicon/microcrystalline silicon tandem solar cell is the next-generation technology of silicon-base thin-film battery, is the important technology approach realizing high efficiency, low cost thin-film solar cells, is the industrialization direction that hull cell is new.Microcrystalline silicon film has been adopted hydrogen PCVD since nineteen sixty-eight since 600 DEG C first preparation by Veprek and Maracek, people start there has been Preliminary study to its potential premium properties, until 1979, Usui and Kikuchi of Japan strengthens chemical vapour deposition technique by the process and low-temperature plasma adopting high hydrogen silicon ratio, prepare doped microcrystalline silicon, people just study microcrystalline silicon materials and application in solar cells thereof gradually.1994, Switzerland m.J.Williams and M.Faraji team proposes to take microcrystal silicon as end battery first, and amorphous silicon is the concept of the laminated cell of top battery, and this battery combines the long-wave response of amorphous silicon good characteristic and microcrystal silicon and the advantage of good stability.The amorphous silicon/microcrystalline silicon tandem battery component sample efficiencies of Mitsubishi heavy industrys in 2005 and Zhong Yuan chemical company reaches 11.1% (40cm × 50cm) and 13.5% (91cm × 45cm) respectively.Japanese Sharp company realizes amorphous silicon/microcrystalline silicon tandem solar cell industryization in September, 2007 and produces (25MW, efficiency 8%-8.5%), Europe Oerlikon (Oerlikon) company announce in September, 2009 the most high conversion efficiency in its amorphous/crystallite lamination solar cell laboratory reach 11.9%, at 2010 6 in the solar cell exhibition " PVJapan2010 " of Yokohama opening, Applied Materials (AMAT) announce that the conversion efficiency that the conversion efficiency of 0.1m × 0.1m module reaches 10.1%, 1.3m × 1.1m module reaches 9.9%.Improve the most effective approach of battery efficiency is improve the efficiency of light absorption of battery as far as possible.For silica-base film, low bandgap material is adopted to be inevitable approach.The low bandgap material adopted as Uni-Solar company is a-SiGe (amorphous silicon germanium) alloy, and their a-Si/a-SiGe/a-SiGe tri-ties laminated cell, small size battery (0.25cm 2) efficiency reaches 15.2%, stabilization efficiency reaches 13%, 900cm 2component efficiency reaches 11.4%, and stabilization efficiency reaches 10.2%, and product efficiency reaches 7%-8%.
For thin-film solar cells, a unijunction, there is no the silion cell of optically focused, in theory maximum electricity conversion be 31% (Shockley ?Queisser restriction).According to band-gap energy reduce order, the silion cell not having optically focused of binode, maximum electricity conversion rises to 41% in theory, and three knot reach 49%.Therefore, developing multi-knot thin film solar cell is the important channel promoting solar battery efficiency.For cadmium telluride diaphragm solar battery, the fusing point of the high or low band gap material matched with cadmium telluride is very low, and unstable, is difficult to form the efficient series-connected solar cells of many knots.For CIGS thin film solar cell, the high or low band gap material matched with CIGS is difficult to prepare, and also not easily forms the efficient series-connected solar cells of many knots.For silicon-based film solar cells, the band gap of crystalline silicon and amorphous silicon is 1.1eV and 1.7eV, and the band gap of nano-silicon changes between 1.1eV and 1.7eV according to the large I of crystallite dimension.Si based compound, the concentration as crystal Si1-xGex band gap (0≤X≤1) foundation Ge can change to 0.7eV from 1.1eV, and amorphous SiGe can 1.4, and Amorphous GaN is about 1.95eV, and this combination is just in time match with the spectrum of the sun.
On the other hand, how to absorb luminous energy fully, improve the electricity conversion of solar cell, allow electronic energy as much as possible be optically excited and to change electric energy into, like this, it is important that the level-density parameter of battery material and few defect cause pass.From technological layer, high-quality and the uniformity of film is ensured while the technological difficulties of thin film deposition are to realize high speed deposition, because film crystallite dimension, the base material of Growing Process of Crystal Particles and growth all has strong impact to the quality of film and uniformity, thus affects the performance of whole battery performance.In film Growing Process of Crystal Particles, due to the abnormal growth of crystal grain, cause grain size uneven, very easily form hole and crack.Be full of the compound that hole in film and crack add charge carrier, and cause leakage current, seriously reduce Voc and FF value.Therefore, solving this technical barrier, is the important channel of preparing efficient thin-film solar cell.
We are at patent ZL200910043930-4, from technical elements in ZL200910043931-9 and ZL200910226603-2, manufacture high efficiency a-Si/ μ C-Si, with a-Si/nC-Si/ μ C-Si binode and three knot silicon-based film solar cells, high density (HD) and hyperfrequency (VHF)-PECVD technology have been developed and for high-quality, the a-Si of large scale, a-SiGe, nC-Si, μ C-Si, A-SiC thin film deposition.Using a-SiC as Window layer, and p-type doping Si-rich silicon oxide film is used for central reflector layer between top a-Si and bottom μ c-Si battery and has been used for increasing the efficiency that a-Si/ μ C-Si binode and a-Si/nC-Si/ μ C-Si tri-tie silicon-based film solar cells.The CVD process optimization of high-quality B doping ZnO x, improves its mist degree and conductivity, and have studied other light capture technique.Three knot silicon-based film solar cells laboratory sample efficiency can reach 15%, have stabilization efficiency be greater than 10% and above business-like a-Si/ μ C-Si (1.1 meters of x1.3 rice) solar module prepare.
The application continues research on the basis of patent ZL200910043930-4, ZL200910043931-9 and ZL200910226603-2, aims to provide a kind of cadmium telluride diaphragm solar battery and the manufacture method thereof with gradient-structure.
Cadmium telluride (CdTe) thin-film solar cells is a kind of thin-film solar cells based on the heterojunction of p-type CdTe and N-shaped CdS.In recent years, CdTe thin film solar cell is high with its optoelectronic transformation efficiency, production cost is low, high stability, absorption spectrum are wide, life cycle terminates the rear advantage such as recyclable, and extremely China and foreign countries pay close attention to.
CdTe thin film solar cell is deposit multilayer film and the photovoltaic device formed successively on glass or other flexible substrate.The CdTe thin film solar cell of general standard is made up of five-layer structure, and as shown in Figure 1, wherein the direction of arrow is direction of illumination.
Ground floor is transparent conductive oxide (English name is Transparent andConductive Oxide, the is called for short TCO) layer deposited on a transparent substrate, mainly plays printing opacity and conduction; The second layer is CdS Window layer, and this layer is n-type semiconductor; Third layer is CdTe absorbed layer, for p-type semiconductor, this layer forms p-n junction with the N-shaped CdS of Window layer, 4th layer is back contacts (English name the is back contact) layer deposited on CdTe absorbed layer, the effect of this layer is the contact berrier reducing CdTe and metal electrode, makes metal electrode and CdTe form ohmic contact; Finally being deposited on, back contact is back electrode (English name is back electrode) layer, and this layer is metal material layer, is connected by external circuit with tco layer, for being drawn by electric current.There is the CdTe thin film solar cell of said structure operationally, wear when there being light and penetrate transparent substrates and tco layer is irradiated to p-n junction, and photon energy is when being greater than p-type CdTe energy gap, electrons gain energy in absorbed layer valence band transits to conduction band, in valence band, produce hole simultaneously, can produce electron-hole pair near p-n junction, the internal electric field effect that the non equilibrium carrier of generation is formed to p-type semiconductor due to n-type semiconductor is drifted about thus generation photovoltaic electric potential to two ends, space charge region.During by p-n junction and external circuit conducting, in circuit, there will be electric current.
Summary of the invention
The technical problem to be solved in the present invention is, for the problem of the defect that thin-film material mates with solar spectral energy gap, crystal grain is formed and produces in growth course that prior art exists, and how fully to absorb sunlight and to improve electricity conversion, cadmium telluride diaphragm solar battery and the manufacture method thereof with gradient-structure are proposed.
For achieving the above object, technical scheme of the present invention is:
Have a cadmium telluride diaphragm solar battery for gradient-structure, comprise the pn knot formed by CdTe absorbed layer and CdS Window layer, the CdTe absorbed layer in the pn knot of described cadmium telluride diaphragm solar battery is Cd xte ygradient-structure, wherein 0≤x≤1,0≤y≤1, described gradient-structure is the sandwich construction with Graded band-gap; Described Cd xte ygradient-structure energy gap between 1.6eV-1.3eV, from the first floor to last layer by high energy gap layer to low energy gap layer even transition, and arbitrary neighborhood two-layer between energy gap difference between 0.01 – 0.1eV.
Described Cd xte ygradient-structure is preferably selected from one or more in following three kinds of forms:
(1) described Cd xte ygradient-structure is the Cd mixed by Cu Erbium-doped xte ylayer even transition is to the Cd of the material doping making energy gap reduce by other xte ythe form of layer, the described material that other makes energy gap reduce is selected from one or more in Zn, Hg, Se, Mg and S; Wherein the atom doped amount of Cu is from 25% even transition to 0%, and the atom doped amount of other material that energy gap is reduced is from 0% even transition to 25%;
(2) described Cd xte ygradient-structure is that the content of Cd increases gradually, the form that the content of Te reduces gradually;
(3) described Cd xte ygradient-structure is the crystallite dimension of CdTe increases to 3 microns gradually form from 10nm.
Above three kinds of forms are the Cd forming energy gap change xte ythree kinds of modes of gradient-structure, can be that the energy gap that wherein a kind of form causes changes, also can be that wherein several form causes energy gap to change simultaneously.
Described Cd xte ythe gross thickness of gradient-structure is preferably between 0.1 micron to 3 microns.
Described Cd xte ythe energy gap of gradient-structure evenly reduces according to the form of energy gap difference between 0.01 – 0.05eV according to preferred.
Described Cd xte yin gradient-structure, the thickness of each transition zone is preferably between 1nm-100nm, more preferably 1nm-10nm.
The described preparation method with the cadmium telluride diaphragm solar battery of gradient-structure, the described CdTe absorbed layer with gradient-structure adopts co-evaporation method preparation, concrete technology controling parameters comprises: first with the CdS layer of concentrated hydrochloric acid removing substrate back before preparation, dilute hydrochloric acid solution washes 3-5 second again, then uses washed with de-ionized water and drying; After substrate is loaded in settling chamber, at the temperature of 380 DEG C-420 DEG C, at CO, CO 2or H 2atmosphere under, preliminary treatment 15-20 minute; When being cooled to 150 DEG C-200 DEG C, the vacuum degree of reative cell is extracted into the pressure of 0.01-0.03 torr, then helium is passed into, when reaching the pressure of 10-20 torr, start to plate buffer layer thin film, then substrate temperature is raised to is 600 DEG C-650 DEG C, CdTe and Zn, the CdTe graphite boat source temperature that Hg and S Erbium-doped is assorted is 650 DEG C-750 DEG C, 1100 DEG C of-1400 DEG C of preparations of Cu raw graphite boat source temperature carry out cadmium telluride gradient-structure, often plate a skim, remove oxide or the CdTe particulate of loose attachment with the nitrogen of drying.
After completing CdTe gradient-structure deposition, caddy is adopted to carry out annealing in process: 60%-80% methanol solution CdTe gradient-structure being placed in a saturated caddy; The substrate of CdTe gradient-structure at 50 DEG C-70 DEG C by immersion after 15 minutes, the N that taking-up is dry 2dry up, put into the helium flow of oven at 100sccm and the O of 25sccm 240-45 minute is toasted under air-flow and at the temperature of 360 DEG C-450 DEG C. after being cooled to 45 DEG C-50 DEG C, remove excessive cadmium by rinsed with deionized water.
Below the present invention be further explained and illustrate:
The described cadmium telluride diaphragm solar battery with gradient-structure comprises unijunction or ties cadmium telluride diaphragm solar battery more.
For cadmium telluride diaphragm solar battery, its gradient-structure is combined to form by following match materials: Cd xte y(1.4-1.6eV) Cd that/Cu, Zn, Hg and/or S Erbium-doped is assorted xte y(1.3-1.5eV) (1>=x>=0, y=2-x) assorted amount of Erbium-doped (the assorted amount of Erbium-doped is from 0 to 25%) by changing Cu, Zn, Hg and S, the ratio of x and y and grain size regulate the energy gap of cadmium telluride material to mate.For Cu doping, when Cu doping is increased to 25% from 0, the crystal structure of cadmium telluride is become the hexagonal structure of Cu2Te form from CdTe form hexagonal structure, its optical band gap is increased to 1.62 electron-volts by 1.48 electron-volts.For S doping, work as CdTe 1-xs xmolecular formula in, when the doping of S is increased to 25% from 0, its optical band gap is reduced to 1.41 electron-volts by 1.51 electron-volts.In addition, experiment proves that the doping of the elements such as Zn, Hg, Mg, Se can cause diminishing of CdTe optical band gap (or energy gap).And growing up with CdTe crystal grain, its energy gap also has the trend diminished.
Many knots of the present invention have in the thin-film solar cells of gradient-structure, and utilizing the gradient-structure of wide gap material to do top electricity knot, is electric energy by the light energy conversion of short wavelength; Utilize the gradient-structure of arrowband material to do end electricity knot, speciality wavelength luminous energy can be converted into electric energy.Owing to more taking full advantage of the spectral domain of sunlight, the thin-film solar cells that many knots have gradient-structure has higher photoelectric conversion efficiency.Gradient-structure change in elevation is determined by the energy gap difference made between material, is regulated by the energy gap size of its material that matches.Every grade of gradient-structure varying width regulates by the thickness forming same gap material.
Compared with prior art, advantage of the present invention is:
The cadmium telluride diaphragm solar battery with gradient-structure of the present invention can be separated and catch free electron, under the exciting of sunlight, forms larger current and improves the efficiency of thin-film solar cells.Described gradient-structure avoids the abnormal growth of crystal grain and the formation in hole and crack, and prepared fine and close, grain size is even, and the high-quality film of energy gap coupling, meanwhile, described gradient-structure is conducive to the abundant absorption to sunlight.Thus, the efficiency of thin-film solar cells is further increased.
Accompanying drawing explanation
Fig. 1 is the structural representation of existing CdTe thin film solar cell.
Fig. 2 is the cadmium telluride diaphragm solar battery structural representation with doping gradient structure;
Fig. 3 is the cadmium telluride diaphragm solar battery structural representation with composition variable gradient structure;
Fig. 4 is the cadmium telluride diaphragm solar battery structural representation with crystallite dimension variable gradient structure;
Fig. 5 is the cadmium telluride diaphragm solar battery preparation technology flow chart of the gradient-structure with composition change.
Fig. 6 is the cadmium telluride diaphragm solar battery preparation technology flow process of the gradient-structure with different Cu, Zn, Hg, S doping content.
Fig. 7 is the cadmium telluride diaphragm solar battery preparation technology flow process of the gradient-structure with the change of different grain size.
Embodiment
Below in conjunction with embodiment, the present invention is described further.
As in Figure 2-4, a kind of cadmium telluride diaphragm solar battery with gradient-structure, according to incident light direction, comprise electrode, CdS Window layer, CdTe absorbed layer, back contact, metal back electrode, back reflection encapsulating material and back-panel glass before glass substrate, TCO successively, wherein CdTe absorbed layer (p layer) and CdS Window layer (i layer) form pn knot.
CdTe absorbed layer in the pn knot of described cadmium telluride diaphragm solar battery is Cd xte ygradient-structure, wherein 0≤x≤1,0≤y≤1, described gradient-structure is the sandwich construction with Graded band-gap; Described Cd xte ythe energy gap of gradient-structure between 1.6eV-1.3eV, from the first floor to last layer by high energy gap layer to low energy gap layer even transition, and arbitrary neighborhood two-layer between energy gap difference between 0.01 – 0.1eV.。
Described Cd xte ythe gross thickness of gradient-structure is between 0.1 micron to 3 microns.Described Cd xte ythe energy gap of gradient-structure is according to the form of the even transition of energy gap difference between 0.01 – 0.05eV.Described Cd xte yin gradient-structure, the thickness of each transition zone is between 1nm-10nm.
Described gradient-structure is selected from one or more in following three kinds of forms:
(1) described Cd xte ygradient-structure is the Cd mixed by Cu Erbium-doped xte ylayer even transition is to the Cd of the material doping making energy gap reduce by other xte ythe form of layer, the described material that other makes energy gap reduce is selected from one or more in Zn, Hg, Se, Mg and S; Wherein the atom doped amount of Cu is from 25% even transition to 0%, and the atom doped amount of other material that energy gap is reduced is from 0% even transition to 25% (as shown in Figure 2), and energy gap is according to the form of the even transition of energy gap difference between 0.01eV;
(2) described Cd xte ygradient-structure is that the content of Cd increases gradually, the form (as shown in Figure 3) that the content of Te reduces gradually, and energy gap is according to the form of the even transition of energy gap difference between 0.02eV; ;
(3) described Cd xte ygradient-structure is the crystallite dimension of CdTe increases to 1 micron gradually form from 10nm, and energy gap is according to the form of the even transition of energy gap difference between 0.05eV; (as shown in Figure 4).
As shown in Figure 5, the manufacture method described in the cadmium telluride diaphragm solar battery of gradient-structure comprises:
(1) glass substrate is cleaned; First glass substrate carries out process 5 – 20 minutes with containing deionized water (DI) solution of 1% soap at 60-80 DEG C, then uses the deionized water of ultrasonic wave and 60-80 DEG C to clean further, and dries.
(2) on substrate, prepare electrode before TCO;
Nesa coating SnO 2: F layer is by the preparation of low-pressure chemical vapor phase deposition (LPCVD) method, and deposition total pressure is at 60torr, and underlayer temperature is 550 DEG C.Tetramethyl tin (TMT) is as the presoma of tin, and CBrF3 is the doped source as F.I-SnO 2the thickness of thin layer of layer is 0.5-2 μm, and resistivity is about 1 ohmcm.As adopted ITO as electrode before TCO, ITO is adopted to be target and magnetically controlled sputter method preparation.
(3) adopt 355nm long wavelength laser that electrode segmentation before TCO is formed the electrode of sub-battery;
(4) glass substrate after scribing is cleaned again;
(5) on the glass substrate with conducting film, CdS film is prepared with chemical solution reaction method;
The raw material of cadmium adopts 0.02-0.05 molar concentration cadmium acetate (CdAc 2), the ammonium acetate (NH of 0.5-2 molar concentration 4ac), the ammoniacal liquor (NH of 10-20 molar concentration 4thiocarbamide (CS (the NH of OH) and 0.05 – 0.1 molar concentration 3) 2) as sulphur source.Chemical solution reaction method depositing temperature is 80-95 DEG C, and CdS film deposit thickness is 80 – 200 nanometers.After plating mould completes, then substrate takes out from bath, puts into warm deionized water, and with ultrasonic process (about 2 minutes) to remove the CdS particulate of loose attachment, then uses dry N 2dry up.
(6) preparation of cadmium telluride gradient-structure:
Cadmium telluride gradient-structure adopts co-evaporation method preparation, and first with the CdS layer of concentrated hydrochloric acid removing substrate back before preparation, then watery hydrochloric acid (wherein hydrochloric acid: deionized water=1:40) solution washes 3-5 second, then uses washed with de-ionized water and drying.After substrate is loaded in settling chamber, under 400 DEG C of atmosphere with CO and CO2 or H2, preliminary treatment 15 minutes.Time after cooling to 200 DEG C, the vacuum degree of reative cell is extracted into the pressure of 0.02 torr, then helium is passed into, when reaching the pressure of 10-20 torr, start to plate buffer layer thin film, then substrate temperature is raised to as 600-650 DEG C, CdTe and Zn, the CdTe graphite boat source temperature that Hg and S Erbium-doped is assorted is that the 1100-1400 DEG C of preparation of 650-750 DEG C, Cu raw graphite boat source temperature carrys out cadmium telluride gradient-structure.
The cadmium telluride raw material of evaporation source to be mixed Cd according to Cu Erbium-doped in cadmium telluride gradient-structure xte y(1.4-1.6eV) Cd that/Cu, Zn, Hg and S Erbium-doped is assorted xte y(1.3-1.5eV) (1>=x>=0,1>=y>=0) by changing Cu, Zn, the assorted amount of Erbium-doped (the assorted amount of Erbium-doped is from 0 to 25%) of Hg and S, and the ratio of x and y is adjusted, and adjust grain size and regulate the energy gap of cadmium telluride material to mate from 10nm to 1 μm, by adjustment substrate temperature from 500 to 650 DEG C, Cu, Zn, the CdTe graphite boat source temperature that Hg and S Erbium-doped mixes is from 600 to 750 DEG C, and deposition rate control CdTe grain size reaches the adjustment of CdTe energy gap.Often plate a skim, remove oxide or the CdTe particulate of any loose attachment with the nitrogen of drying.
(7) CdCl 2annealing in process
After completing CdTe gradient-structure deposition, caddy is adopted to carry out annealing in process.Do not have the photoelectric conversion of the cadmium telluride solar cell of annealed process generally to only have between 6% and 10%, and the optoelectronic transformation efficiency after caddy annealing in process can reach 12%-15%.Before annealing in process process, CdTe gradient-structure is placed in 75% methanol solution (saturated solution: 500 ml methanol contain 7.5 grams of caddies) of a saturated caddy.The substrate of CdTe gradient-structure is at 50-70 DEG C by immersion after 15 minutes, and the dry N2 of taking-up dries up.Put into the helium flow of oven at 100sccm and the O of 25sccm 2toast 40 minutes under air-flow and at the temperature of 360 DEG C-450 DEG C.After being cooled to 50 DEG C, remove any excessive cadmium by rinsed with deionized water.
(8 adopt machinery and laser technology scribing film plating layer, are convenient to metal back electrode as wire connexon battery;
(9) back-contact electrode is prepared
Adopt 88:1:35 phosphoric acid: nitric acid: the substrate of solution to CdTe gradient-structure of deionized water cleans and etch, etching be about 30-60 second total time, form the surface of a clean rich Te.
The 4 grams of HgTe:Cu atomic ratio of about 2% (Cu) are doped to row in 10g graphite powder becomes graphite paste as back electrode raw material.Back electrode is prepared by the method for mould printing, in oven in the helium flow of 100sccm, at 250 – 350 DEG C, 30 minutes, then the method preparation of mould printing stamps the silver slurry of thin layer, and 1 – is toasted 2 hours in 100 DEG C of baking boxs.Also have and adopt magnetron sputtering to prepare metal back electrode;
(10) adopt machinery and laser technology scribing Cadimium telluride thin film and metal back electrode, form single sub-battery;
(11) laser scribing is carried out to battery edge;
(12) circuit connection and encapsulation are carried out to battery.

Claims (8)

1. have a cadmium telluride diaphragm solar battery for gradient-structure, comprise the pn knot formed by CdTe absorbed layer and CdS Window layer, it is characterized in that, the CdTe absorbed layer in the pn knot of described cadmium telluride diaphragm solar battery is Cd xte ygradient-structure, wherein 0≤x≤1,0≤y≤1, described gradient-structure is the sandwich construction with Graded band-gap; Described Cd xte ythe energy gap of gradient-structure between 1.6eV-1.3eV, from the first floor to last layer by high energy gap layer to low energy gap layer even transition, and arbitrary neighborhood two-layer between energy gap difference between 0.01 – 0.1eV.
2. there is the cadmium telluride diaphragm solar battery of gradient-structure according to claim 1, it is characterized in that, described Cd xte ygradient-structure is selected from one or more in following three kinds of forms:
(1) described Cd xte ygradient-structure is the Cd mixed by Cu Erbium-doped xte ylayer even transition is to the Cd of the material doping making energy gap reduce by other xte ythe form of layer, the described material that other makes energy gap reduce is selected from one or more in Zn, Hg, Se, Mg and S; Wherein the atom doped amount of Cu is from 25% even transition to 0%, and the atom doped amount of other material that energy gap is reduced is from 0% even transition to 25%;
(2) described Cd xte ygradient-structure is that the content of Cd increases gradually, the form that the content of Te reduces gradually;
(3) described Cd xte ygradient-structure is the crystallite dimension of CdTe increases to 3 microns gradually form from 10nm.
3. there is the cadmium telluride diaphragm solar battery of gradient-structure according to claim 1 or 2, it is characterized in that, described Cd xte ythe gross thickness of gradient-structure is between 0.1 micron to 3 microns.
4. there is the cadmium telluride diaphragm solar battery of gradient-structure according to claim 1 or 2, it is characterized in that, described Cd xte ythe energy gap of gradient-structure is according to the form of the even reduction of energy gap difference between 0.01 – 0.05eV.
5. there is the cadmium telluride diaphragm solar battery of gradient-structure according to claim 1 or 2, it is characterized in that, described Cd xte yin gradient-structure, the thickness of each transition zone is between 1nm-100nm.
6. there is the cadmium telluride diaphragm solar battery of gradient-structure according to claim 5, it is characterized in that, described Cd xte yin gradient-structure, the thickness of each transition zone is between 1nm-10nm.
7. there is the preparation method of the cadmium telluride diaphragm solar battery of gradient-structure according to one of claim 1-6, it is characterized in that, the described CdTe absorbed layer with gradient-structure adopts co-evaporation method preparation, concrete technology controling parameters comprises: first with the CdS layer of concentrated hydrochloric acid removing substrate back before preparation, dilute hydrochloric acid solution washes 3-5 second again, then uses washed with de-ionized water and drying; After substrate is loaded in settling chamber, at the temperature of 380 DEG C-420 DEG C, at CO, CO 2or H 2atmosphere under, preliminary treatment 15-20 minute; When being cooled to 150 DEG C-200 DEG C, the vacuum degree of reative cell is extracted into the pressure of 0.01-0.03 torr, then helium is passed into, when reaching the pressure of 10-20 torr, start to plate buffer layer thin film, then substrate temperature is raised to is 600 DEG C-650 DEG C, CdTe and Zn, the CdTe graphite boat source temperature that Hg and S Erbium-doped is assorted is 650 DEG C-750 DEG C, 1100 DEG C of-1400 DEG C of preparations of Cu raw graphite boat source temperature carry out cadmium telluride gradient-structure, often plate a skim, remove oxide or the CdTe particulate of loose attachment with the nitrogen of drying.
8. there is the preparation method of the cadmium telluride diaphragm solar battery of gradient-structure according to claim 7, it is characterized in that, after completing CdTe gradient-structure deposition, caddy is adopted to carry out annealing in process: 60%-80% methanol solution CdTe gradient-structure being placed in a saturated caddy; The substrate of CdTe gradient-structure at 50 DEG C-70 DEG C by immersion after 15 minutes, the N that taking-up is dry 2dry up, put into the helium flow of oven at 100sccm and the O of 25sccm 240-45 minute is toasted under air-flow and at the temperature of 360 DEG C-450 DEG C. after being cooled to 45 DEG C-50 DEG C, remove excessive cadmium by rinsed with deionized water.
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CN105355699A (en) * 2015-11-04 2016-02-24 湖南共创光伏科技有限公司 Multi-junction multi-lamination cadmium telluride thin film solar cell and preparation method thereof
CN106356417A (en) * 2016-11-25 2017-01-25 中国科学院电工研究所 CIGS/CdTe gradient absorbing layer thin-film solar cell and preparation method thereof
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CN107910394A (en) * 2017-11-06 2018-04-13 成都中建材光电材料有限公司 A kind of absorbed layer of cadmium telluride diaphragm solar battery mixes selenium technique
CN110176503A (en) * 2019-06-05 2019-08-27 浙江力晟玻璃科技有限公司 A kind of cadmium telluride power generating glass
CN114360884A (en) * 2021-12-31 2022-04-15 华南理工大学 High-magnetic-induction low-loss gradient nanocrystalline magnetic powder core suitable for high-frequency inductance element and preparation method and application thereof

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