The lead–acid battery was invented in 1859 by French physicist Gaston Planté and is the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio.
The indirect band gap transition occurs between the band and the local shallow energy level, and the indirect band gap pull is 1.408 eV.Phonon Energy ( EP ) * 21M eV in Indirect Band Gap Transition.
Among them, only direct band gap transition can produce free electron-hole pairs, which is related to photovoltaic effect.The direct band gap changes almost linearly with temperature, and the direct band gap pull = l 61ev when Kelvin temperature is 0 is extrapolated, so 3eg / 3t - 0.41 mev / k [ 23 ].
Although there are some differences in the CdTe absorption coefficient curve A given in various documents, the curves given in Adac HP 1 " and Palik [ 24 ] standard data documents almost coincide, and the cut - off wavelength ( Ag ) is also similar.The peak at wavelength A = 820 nm can be observed in Adachi curve, which is caused by exciton generation. Whether such light absorption contributes to photovoltaic effect at room temperature is still a question to be discussed [ 25 ].In the process of numerical modeling, we will use Adachi's data as the absorption coefficient curve A, but it needs to be modified near the band edge to modify Albin - based measurements [ 26 ] and Palik's data.Tousek et al [ 27 ] have accurately measured the sub-band gap absorption of CdTe layer prepared by chemical water bath deposition of CBD using high resolution steady photoinduced current method CPM.Wood et al. expanded the complex refractive index ( n' = n + / / c ) to the power of wavelength a by series ⑽. in fact, the curve from wood in. 1 was calculated from the power series / c of extinction coefficient according to a = 4 roc / a ..
AMI. 5 Spectral illumination can calculate the ratio / ( < / ).CdTe with a thickness of only 1 mm is enough to convert 92 % of useful solar photons, so CdTe is obviously suitable for preparing a thin film solar cell absorption layer.In contrast, crystalline silicon solar LEAD ACID BATTERY require a thickness of 200 to achieve a similar photon conversion ratio.
At the junction of CdTe and CdS, a CdTe - CdS mixed phase will appear:
There are S - rich CdTe phases, CdTe _ S, XL in the CdTe absorption layer.There is a Te - rich CdS phase in the CdS buffer layer, CdS hT y a ..
The band gap of mixed phase depends on group division of labor or J in the form of parabolic function.When CdS accounts for about 25 % of the atom content in CdTe, the band gap eg = l 40ev of the smallest mixed phase is reached.The mixed phase shifts the quantum efficiency of cadmium telluride thin film solar LEAD ACID BATTERY to a long wavelength by tens of RUN:
At A 520 nm, CdS Te.The mixed phase increases the absorption of the buffer layer, resulting in loss of photovoltaic effect.At A860 nm, CdTe S, the mixed phase increases the absorption of the absorption layer and enhances the photovoltaic effect.
The enhancement of light absorption in the infrared band is usually not enough to compensate for the loss in the green band.The band gap data of CdTe and other group N - VI alloys ( e.g. ZnTe ) can be found in [ 20, 28, 30 ].
Electrical Properties of Cadmium Pounding
For the electrical characteristics of CdTe and CdS materials required for numerical modeling of CdTe thin film solar LEAD ACID BATTERY, see actual .1.Among them, almost all electrical characteristic parameters are not uniform, and the data given in different documents are scattered, so the actual. 1 can only be used as a reference.The parameters related to doping and recombination are not real material properties, but their values are determined with respect to specific deposition techniques.
The ionization energy of shallow acceptor increases with the number of atoms: Li is 58MeV and Au is 263 MeV;N is 56 MeV and AS is 92 MeV.The energy level of the donor dopant is shallower than that of the acceptor, and its ionization energy is about 1315 mev [ 33 \ if Zn replaces CD position, s or se replaces te position, these isoelectric elements will not attract impurity energy level [ 33 ].Other impurity elements will become deeper donor centers or acceptor centers, and relevant data can be found in [ 32, 33, 35 ].
The doping of CdTe still has more complicated problems. Inherent defects will form complexes, become doping centers themselves, or compensate for impurity doping.The impurity that has the greatest impact on cadmium telluride thin film solar LEAD ACID BATTERY is C1, which is usually introduced into CdTe through " CDC L2 treatment".A Cl atom replaces a Te atom and becomes a shallow donor with a positive charge.C shallow donor and CD vacancy v with divalent negative charge form a single acceptor complex with monovalent negative charge ( C1 right - v & wide.We will further discuss the influence of C1 atmosphere on CdTe in section 7.3.1.
Another impurity affecting cadmium telluride thin film solar LEAD ACID BATTERY is Cu.If a low concentration of Cu is introduced, Cu will occupy the CD position and CuCa will become the shallow acceptor.If a large number of Cu atoms are introduced, some Cu will become interstitial atoms and Cu will act as a donor to partially compensate for the CuA acceptor.The formed shallow donor compensates for the shallow acceptor ( or vice versa ) and will release energy almost equivalent to the band gap EG.Because the band gap of CdTe is larger than CUI NSE2 or ⑴, Ga ) Se2, the self-compensation trend of CdTe is more obvious.Although there are reports that the impurity defect density of CdTe crystals is very high, exceeding 1017 CNT 3, the actual doping concentration limit of CdTe thin film solar LEAD ACID BATTERY is 10151016 cm - 3.For further discussion of CdTe self-compensation and impurity doping, see document [ 3640 ].
The composite properties of CdTe materials are very dependent on the preparation method, and there are great differences between samples.The recombination of minority carriers in the absorption layer is the most important to the photovoltaic effect.Therefore, electron lifetime ( RN ) and electron diffusion length ( LN ) are important electrical characteristics of cadmium telluride thin film solar LEAD ACID BATTERY.The methods for measuring RN are:
Photoinduced luminescence decay;
Attenuation of open circuit voltage after turning off lighting.
The methods for measuring LN are:
Electron beam induced current EBIC;
Spectral response QEM.
EBIC is a semiconductor analysis technology based on scanning electron microscope SEM, which relies on electron-hole pairs generated in the semiconductor by microscopic electron beams and can be used to analyze the buried junction region, defect or minority carrier characteristics of the semiconductor.
It is difficult to analyze the data from literature directly, because the excitation conditions of photo-induced luminescence decay and EBIC tests are high injection, which is quite different from the conventional operation conditions of low injection of solar LEAD ACID BATTERY.
In addition, the two-dimensional influence of polycrystalline grain also increases the analysis and test RN and ￠ 0 ￠ 5 ￠ 0 ￠ 0 ￠ 0 ￠ 0 ￠ 0 ￠ 0 ￠ 0 ￠ 0 ￠ 0 ￠ 0.The difficulty of data [ 42 ].Therefore, the apparent diffusion length is often used to better describe minority carrier recombination.The value of is 0.24 / im and the corresponding life is in ns range or less.
cadmium sulfide buffer layer material
In cadmium telluride thin-film solar LEAD ACID BATTERY, the N - type CdS layer forms a P - N junction with the P - type CdTe absorption layer.In the early research of CDS / CdTe batteries, the CDS layer was the only transparent layer ( for the band larger than 520 nm ), so it was called " window layer".In today's cadmium telluride thin film solar LEAD ACID BATTERY, the window layer is a transparent conductive oxide TCO, typically SnO, or ZnO, and the CDS layer is thinner, commonly referred to as a " buffer layer".
Cadmium telluride thin film solar LEAD ACID BATTERY have certain requirements on CDS buffer layer in several aspects:
Crystallography: Buffer layer or window layer / buffer layer structure is used as the bottom layer for absorbing layer growth, which requires a thicker buffer layer and a larger grain size.On the other hand, the buffer layer should not be too thick, otherwise voids will form a shunt between the absorbing layer and the front contact, thus requiring a minimum thickness of several tens of nm.
Crystallography: During the high temperature process of CdTe deposition or post-deposition treatment, the O buffer layer that will cause mutual diffusion between CdS and CdTe needs to be thick enough not to be completely consumed.CDC L2 processing promotes mutual diffusion.See section 7.3.1 ), so CDC L2 processing has both positive and negative effects on LEAD ACID BATTERY operation.When the mutual diffusion is too strong ( penetrating more than 1 ), the photogenerated current will decrease ( see section 7.2.1 ).In the CdTe prepared by screen printing, the CdTe S formed by mutual diffusion is limited, which is better than the crystalline property of the porous pure CdTe layer on the top..Another advantage of mutual diffusion is about the interface state, which will be explained next.
Electricity / crystallography: Theoretically, lattice mismatch between CdS buffer layer and CdTe absorption layer will increase the density of state N at the interface and affect LEAD ACID BATTERY performance.N oc = 4 - is the distance CDs The interface of CdS hexagonal lattice is on the crystal plane, and the interface of D = A -, CdTe cubic lattice is on the crystal plane.According to the actual value of. 1, although the lattice mismatch is large, the performance of CDS / CdTe cell structure without interface passivation step is better.Therefore, people are not looking for buffer layer materials that match the lattice better.It has been proved that a narrow interdiffusion region of 100nm between CdS and CdTe can smoothly transform the two crystal lattices, thus reducing the surface state.However, the same number of in vivo recombination states will still be distributed over the 100 nm wide transition region, and the final effect will depend on the details of the recombination distribution in the interface region positively or negatively.
Electricity: The energy bands of buffer layer and absorption layer in cadmium telluride thin film solar LEAD ACID BATTERY will be more or less mismatched.The conduction band dislocation ( conduction band dislocation, △?, ) is determined by the electron affinity of the two materials: fenger =.The electron affinity energy is the energy level difference between the vacuum energy level and the conduction band.If △ ▲;Is a larger positive value, the junction CdTe conduction band will be higher than the CdS conduction band, a " cliff" will appear in the energy band diagram, and the open circuit voltage will decrease. If it is a larger negative value, the junction CdS conduction band will be higher than the CdTe conduction band, a " spike" will appear in the energy band diagram, and the short circuit current density will decrease.However, the influence of conduction band misalignment is limited and | voj < 0.3 ev can be tolerated.The normal values of electron affinity of pure materials are 5eV, % = 4.28 eV, forming a small cliff of 0.22 eV can be tolerated' however, the X values reported in the literature are relatively dispersed.darmstadt University of Technology ( Darmstadtuniversityoftechnology / 45 ) reported smaller conduction band dislocations in the real CDS / CdTe structure, three?0'03eV。
Electricity: If the hole diffusion length ( Hp ) of CdS is on the order of the buffer layer thickness, the incident light absorbed by the CdS layer will theoretically contribute to the photogenerated current.However, it is still worth discussing whether there is such a contribution.' Generally, it is assumed that LP is very small and the light absorption of CDS buffer layer is completely lost.For other electrical characteristics, see Actual 1.
Electricity: In the cadmium telluride thin film solar cell prepared by Mitsubishi in Japan earlier, there was no TCO layer. CdS layer is the only window layer, and the required conductivity is high enough that the square resistance of the CdS layer collected laterally by the contact electrode cannot exceed tens of FL / □, which requires a relatively thick CdS layer with a typical thickness of 30 mm after screen printing and sintering and doped with In or Ga.If a TCO window layer is used, the lateral conductivity requirement of CDS is significantly reduced.Therefore, TCO / CDS / CdTe structure is widely used at present.
Optics: In order to reduce the light absorption of the buffer layer, the thinner the buffer layer is, the better, or a wider band gap material is required.However, replacing the CDS layer with CDZ NS, ZnS, ZnSe, S NO2 or other wide band gap N - type materials has not been successful.The study of CDZ NS / CDS double buffer layer can be found in reference [ 47 ].
The absorption coefficient curve of each layer of the cadmium - linked thin-film solar cell material in the short wavelength region is shown in the actual .4.Assuming that the human light absorbed by the TCO window layer and the CDS buffer layer is completely lost and the human light absorbed by the CdTe layer is completely converted into photo-generated current, the ideal quantum efficiency ( QEIDEAI ) can be obtained from the actual data of .4:
Chemical water bath deposition of CBD can produce a closed CDS layer with a minimum thickness of 20nm, which is also a technique used for buffer layer of copper indium gallium selenium thin film solar LEAD ACID BATTERY.However, as explained earlier, cadmium telluride thin film solar LEAD ACID BATTERY need a thicker CDS layer.
The difference of CDS buffer layer thickness between two different thin film solar cell technologies is:
cadmium telluride thin film solar LEAD ACID BATTERY are mostly arranged on the upper layer,
CdS buffer layer needs to be exposed to high temperature during deposition of CdTe absorption layer;Most of the copper indium gallium hit thin film solar LEAD ACID BATTERY are substrate configurations.CdS buffer layer is deposited on CIGSE absorption layer at low temperature.
In order to be compatible with CdTe deposition technology, thick CdS layers are deposited by near-space sublimation CSS technology.The ideal quantum efficiency Q ￠ in the 350 500 nm wavelength range can be calculated from equation ( 7.2 ), and the DFAL is a function of decreasing CDS buffer layer thickness.Thickening the CDS buffer layer can make the loss of photogenerated current reach several mA / cm2 [ 49 ].
Albin compared the preparation techniques of CBD and CSS CDS layers [ 5 ].If the thickness of CDS layer is the same, CBD technology is better than CSS technology:
The grain size is smaller.
Light absorption is lower;
the crystallinity is lower;
showing a range of band gap values;
Contains more zeros;
Better prevent mutual diffusion.
Window layer material
The function of the window layer is to transmit human light into the CdTe absorbing layer, so it is desirable for the window layer material to have the characteristics of wide band gap and low scattering.Due to free carrier absorption, various transparent conductive oxides TCO exhibit lower transmittance in the infrared band.In cadmium telluride thin film solar LEAD ACID BATTERY, only human light with a wavelength of a < 860 nm is converted into current, and free carrier absorption is not a problem.However, the band gap of CUI NSE2 or Cu ( In, Ga ) Se2 of the Cu - In - Ga - Se thin film solar cell is narrow, and its window layer needs to transmit human photons with longer wavelengths.
In order to collect the photogenerated current laterally to the contact electrode, the square resistance of TCO needs to reach about 10ft / □ or less.Therefore, the thickness of TCO needs to be balanced between high transmittance and low square resistance.TCO usually needs to be doped.The TCO layer should also be thick enough to form a diffusion barrier to prevent unwanted substances from coming from the substrate / s NO2 / CDs [ 1 ], while the window layer structure for laboratory conversion efficiency recording is borosilicate glass / 01251104 / 211231104 / 0 <2 ].
Research Direction of Cadmium Telluride Thin Film Solar Cells
Activation Treatment of Cadmium Telluride
The activation of CdTe and other Group II materials with C1 - containing substances has been studied for a long time.In the late 1980s, the activation process using CDC L2 as a Cl source was applied to cadmium telluride thin film solar LEAD ACID BATTERY [ 55 ] and was quickly widely used by the research industry as a necessary process step [ 56 ]. The CDC L2 activation process was even called " magic formula" O just started, and the CDC L2 activation process step was [ 5S ]:
dropping CH3OH solution containing CDC L2 on the glass / TCO / CDS / CdTe substrate;volatilize that CH3OH solvent;
Heat treatment at moderate temperature.
At the same time, activation processing technology has been improved, hoping to use a more suitable method for mass production:
The thin solid CDC L2 film is used as a Cl source for evaporation [ 57 ] or near-space sublimation of CSSM.
Gas CDC L2;
Other Cl - containing gases: Cl2, HC P8' 59 ];
Other CD halides: CDBR 2, CD L2;
Other CI - containing salts: Mn CLP 0, NAC P1 ];
Other heat-treated ambient gases: inert gas, vacuum, change of O content [ 62 ].
The effect of activation treatment on cadmium telluride thin film solar LEAD ACID BATTERY has been studied with high intensity [ 63 ], and its main effects can be summarized as follows:
Grain growth occurs when the initial grain size is small ( on the order of 1 );However, grain growth does not occur when the initial grain size is larger ( > 1 ).If the CdTe layer is prepared with CSS, the crystal grain size immediately after deposition is relatively large, CdCl, and the crystal grain growth observed after treatment is not obvious ( although there are not many reports about this?）。
The crystal boundary structure disappears and the internal crystal structure of the crystal grain can always be improved.
The mutual diffusion of CdS and CdTe interfaces can be enhanced.Mutual diffusion can reduce the porosity in the material and make the crystal lattice of the interface change smoothly, but too strong mutual diffusion can make the CdTe absorbing layer thinner, thus reducing the photogenerated current ( see section 7.2.3 ).The effect of CDC L2 activation on mutual diffusion has been widely reported in MM83.
Promoting P - type doping or establishing P - type doping ( doping type conversion ) increases minority carrier lifetime Rn.
The density of electron deep energy levels in the body or interface is reduced [ 64 ], but other deep energy levels [ 69' 7 ] will be attracted.The mechanism of inducing or annealing to remove deep energy level is to increase CD vacancy and enhance Cl and?The interaction of.
Excessive activation will lead to a deeper recombination center, reducing the open circuit voltage 1469' 71 \ and also causing loss of adhesion m.
The exact mechanism of CDC L2 activation is still not completely clear.The formed CdTe and CDC L2 eutectic has a melting point of 505 C, which is much lower than 568 C of CDC L2.It is impossible to explain the ordinary CDC L2 activation treatment below 500 C by the existence of liquid phase and the mechanism of liquid phase sintering.However, it can only be assumed to be gas phase transport, which may be due to the important role played by intermediate volatile compounds such as TEC L2 [ 72 ].Eutectic crystal refers to the simultaneous formation of two different solid phases from one liquid phase during solidification, while liquid phase sintering is the sintering of powdered or massive solids with two or more components in the presence of the same liquid phase and solid phase.Recently, Hiie discovered the existence of oxide CdTe 3, which can reduce the melting point of CdTe - CDC L2 eutectic to 455480 C [ 73 \ Now it is generally believed that it is necessary to introduce C1 into cadmium telluride thin film solar LEAD ACID BATTERY just like introducing Na into copper indium gallium selenium thin film solar LEAD ACID BATTERY ( see 220.127.116.11 Festival ).Even if activation treatment is not carried out after deposition, special activation treatment should be carried out during CdTe deposition, for example:
In the screen printing process, CDC L2 particles are added with human CdTe slurry;During the electroplating process.Addition of C1 salt.
Obviously, the activation process will more or less change the input parameters of the numerical modeling of cadmium telluride thin film solar LEAD ACID BATTERY.Moreover, the doping and recombination properties are particularly susceptible to activation treatment.Therefore, it is necessary to describe the details of deep and shallow energy levels:
Energy level distribution;
Capture cross section.
Back contact structure
Finding a stable ohmic contact of CdTe layer for CdTe - CdTe thin film solar LEAD ACID BATTERY is not an easy task, in most cases Schottky contact.P - type CdTe material has a wide band gap of' EG - 1.45 eV, so it is difficult to increase its doping concentration.The Schottky barrier of the contact electrode is also called contact barrier ( 0h ), which determines the characteristics of Schottky contact.If the hole fermi level is approximately x + ( the electron affinity energy x is the level difference between the vacuum level and the conduction band, assuming that the hole fermi level is very close to the valence band )' the metal work function of the contact electrode is, then = x + s one less m.Due to the private nature of metal materials?Limited, do, > 0, such a semiconductor junction can be said to be more like a schottky contact than an ohmic contact' with a smaller sense' forming a contact barrier that prevents holes from entering the metal contact electrode from the p - type CdTe layer.
We can calculate 0b [ 14' 74 ] according to the standard semiconductor theory.There will be a very thin intrinsic oxide layer between the metal and the semiconductor, with a thickness of ta and a dielectric constant of e!.The surface state energy density exists in the interface band gap, and the energy distribution is between e v + must and.Fermi level pinning barrier, 0.) is a fitting parameter.If the doping concentration is not too large, the contact barrier is:
Where g is the intrinsic oxide layer capacitance per unit area, c -, = eieo / di;Css is the surface state capacitance per unit area. under ideal conditions, there is no intrinsic oxide layer ( 4 - 0, ( -?Or there is no surface state - the ideal approximation is:
The electron affinity energy x of CdTe material is usually 4.3 - 4.5 ev. in order to make the contact barrier 0b < o.5 ev, a higher work function of the metal contact electrode is required, 0 m > 5.5 ev.If we do not consider expensive rare metals, it will be difficult for the work function of metals to reach such a high value.
The other extreme case is approximately Fermi level pinning, the intrinsic oxide layer is too thick g - * 0, or the surface state is too large ( CSS c ), and the contact barrier is determined by Fermi level pinned at the lowest surface state level position e v + 0o:
In many materials, the Fermi level pinning barrier is 1 / 31 / 2 of the band gap, so it will cause a higher contact barrier and is independent of the metal material of the contact electrode.Ponpon studied the contact barrier between different metal materials and N - type or P - type CdTe materials [ 75 ], and gave the contact barrier identification as a function of metal work function Tunn N ..The best fitting curve obtained from the experimental data gives ci / ( c, + CSS ) = 0.08, 0o = o.63ev by equation ( 7.3 );The ideal scenario assumes x + ge = 0b + m = 5.29 ev according to equation ( 7.4 );The Fermi level pinning is set to 0 by Equation ( 7.5 ).=0.67eV。It is clear from the actual. 6 that the contact barrier is always high.Selecting the appropriate metal material for the contact electrode within a limited range will not have much influence on the contact barrier.Moreover, the contact barrier can only be roughly predicted by equation ( 7.3 ) and the constant values are required to be reasonable.The exact value of each constant needs to be determined by experiment.Recently, Kraft et al. updated the contact barrier between CdTe and ZnTe thin films [ 76 ].
The material properties of CdTe determine that there are not many contact electrode metal materials available.If the CdTe layer is heavily doped, the contact electrode characteristics can be improved.However, CdTe with doping concentration over 1016 CNT 3 will have problems because CdTe tends to self - compensate, i.e. impurities act as both donors and acceptors and cancel out.Self - compensation that easily occurs in the case of high CdTe doping concentration can be attributed to:
The band gap of CdTe is quite large.
The activation process introduces C1 ( see section 7.3.1 );
Possible complications between impurities and inherent defects ( see section 7.2.2 ).
Contact electrodes not only require low resistivity, but also should have high stability:
During the operation of the LEAD ACID BATTERY, impurities are not allowed to diffuse from the contact electrode to the active layer, but can only be tolerated during the high temperature process of preparing the LEAD ACID BATTERY.The contact electrode material cannot chemically react with the CdTe absorbing layer.When a double-layer or multi-layer structure is used, no interaction can occur between adjacent layers.
Therefore, the preparation of high-quality stable contact electrodes for cadmium telluride thin-film solar LEAD ACID BATTERY is a challenging research and development direction, and some process steps have been developed at present:
Surface pretreatment: BR - CH, OH solution or HNO 3 - H3PO4 mixed solution;applying a diffusion barrier layer to prevent unwanted diffusion or reaction;
The diffusion of extrinsic dopants from the contact electrode or buffer layer to the CdTe layer is controlled.
The contact electrode containing Cu has good performance at the initial stage of LEAD ACID BATTERY operation, and Cu forms a shallow donor energy level in CdTe. However, the long-term performance of the contact electrode containing Cu is a problem [ 77 ] because Cu diffuses through the CdTe layer under certain conditions and accumulates in the vicinity of the CdS junction region and in the CdS layer.The diffusion of impurities, Cu, etc. from the graphite contact electrode to the CdTe layer and the influence on the doping and stability of the cell have been studied [ 78 - 83 ].No man-made stable contact electrode structure containing Cu has been intensively developed.The chemical stability between CdTe layer, several buffer layers and contact electrode materials has also been carefully studied [ LB84 ].Finally, a stable Cu - free contact electrode structure was determined m: CdTe / etch / Sb2Te3 / mo.
The existence of contact barrier will affect the volt-ampere characteristic curve of cadmium telluride thin film solar LEAD ACID BATTERY.The curve bending in the # # forward bias quadrant is commonly referred to as " flip" mo. when the contact barrier is over about 0.45 ev, the main impact on LEAD ACID BATTERY performance is the decrease of the fill factor ff and the corresponding loss of conversion efficiency 7 [ 86' 87 ].The approximate equation of conversion efficiency loss is [ 87 ]:
Where, % is the conversion efficiency without a contact barrier;JPH is photogenerated current density;Man is the contact saturation current density of the contact electrode Schottky barrier, which is thermally activated by the contact barrier.The open circuit voltage v, x = 0.848 v, = 0.03 recorded by the laboratory conversion efficiency of copper telluride thin film solar LEAD ACID BATTERY.If contact saturation current is 9 oc
The density is higher than the photogenerated current density jph, ln ( l + ) < 0.69, and the conversion efficiency is almost not lost.
The secondary effect of the contact barrier of cadmium telluride thin film solar LEAD ACID BATTERY has also been reported:
A minority carrier ( electron ) current will appear in the back contact, resulting in a " cross" of volt-ampere characteristic curves. 87 \ in some special cases, a set of volt-ampere characteristic curves given by a series of experiments will cross at the same point. in some cases, the cross effect is particularly obvious: red light irradiation, thin LEAD ACID BATTERY ( < 5, the larger electron diffusion length m caused by the two-dimensional effect.
When the CdTe doping of the back contact is high enough, the hole current density through the contact electrode needs to be described by the drift and diffusion of the space charge layer SCL.This effect weakens the phenomenon that the volt-ampere characteristic curve turns over, and the final room temperature volt-ampere characteristic curve is as weak as the contact barrier, even without the contact barrier.
The high doping of the contact electrode makes the contact barrier obviously dependent on the bias voltage and the human light intensity [ 9 ].Although this effect prevents the contact barrier from being determined by the volt-ampere characteristic curve at room temperature, the filling factor FF and the conversion efficiency 7 will be affected in a positive way as a whole.
To sum up, in order to further develop thin-film solar LEAD ACID BATTERY as the main non-carbon dioxide energy sources, considerable support is needed to improve their scientific research basis so as to reduce the technical risks associated with explosive growth.
In addition to these technical risks, the development of thin film solar LEAD ACID BATTERY to large-scale production may also encounter certain industrialization risks.In fact, the industrialization risk of explosive growth is no lower than the technical risk in the research and development stage.The 10 % 15 % conversion efficiency 1cm2 - sized solar cell is only proof of concept, while the LEAD ACID BATTERY area required to be produced in the production base for successfully manufacturing 1m2 module with an annual capacity of 25 MWp / a is about 109 times as large as that of the proof of concept.Enterprises newly entering the field of thin film solar cell technology often underestimate the risk of such industrialization, which may result in significant financial losses.Higher technical risk and financial risk will be the biggest challenge for thin film solar cell manufacturers to expand their production scale.However, there will be another industrialization risk when the annual production capacity is expanded to TWP level, but the annual production capacity of 4t wp / a is only about 105 times larger than that of 25mwp / a ..
In order for photovoltaic power generation to truly realize the terawatt challenge, technologies in photovoltaic power storage and photovoltaic synthetic fuels, such as decomposition of water and reverse methanol fuel LEAD ACID BATTERY, are also needed.In addition to the challenges of these technologies and energy systems, it is also hoped that the cost of photovoltaic power generation will be lower than our calculation results in this chapter.Therefore, further in-depth research and development work is needed.
In order to realize the potential huge returns, the development of thin film solar LEAD ACID BATTERY will face the essential technical risks and the ongoing industrialization risks, so the related research and development and large-scale production will need long-term financial support from the government and the private sector.The development potential of thin-film solar LEAD ACID BATTERY should have been thoroughly analyzed, and the realization of affordable access to the Internet and the Taiwa challenge will surely bring rich returns to such investors.
Lead-acid batteries【H Bode - 1977 - osti.gov】
Lead-acid battery【DB Edwards, WE Rippel - US Patent 4,603,093, 1986 - Google Patents】
Lead/acid batteries【KR Bullock - Journal of power sources, 1994 - Elsevier】
Lead-acid battery【JJ Rowlette - US Patent 4,405,697, 1983 - Google Patents】
Lead-acid battery【K Honbo, E Hoshi, Y Muranaka, S Takeuchi - US Patent 7,083,876, 2006 - Google Patents】
Lead-acid battery【E Hohjo, K Kishimoto, Y Kasai, H Nakashima… - US Patent …, 1992 - Google Patents】
Lead acid battery【R Chen - US Patent App. 29/335,447, 2010 - Google Patents】
A mathematical model for lead-acid batteries【ZM Salameh, MA Casacca… - IEEE Transactions on …, 1992 - ieeexplore.ieee.org】
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Lead–acid battery - Wikipedia
Talk:Lead–acid battery - Wikipedia
VRLA battery - Wikipedia
Deep-cycle battery - Wikipedia
Electric battery - Wikipedia
Automotive battery - Wikipedia
Rechargeable battery - Wikipedia
Float voltage - Wikipedia
UltraBattery - Wikipedia
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