WO2018119675A1 - Method for visualizing defects in a semi-finished cdte thin film solar cell - Google Patents
Method for visualizing defects in a semi-finished cdte thin film solar cell Download PDFInfo
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- WO2018119675A1 WO2018119675A1 PCT/CN2016/112397 CN2016112397W WO2018119675A1 WO 2018119675 A1 WO2018119675 A1 WO 2018119675A1 CN 2016112397 W CN2016112397 W CN 2016112397W WO 2018119675 A1 WO2018119675 A1 WO 2018119675A1
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- Prior art keywords
- solar cell
- semi
- ion solution
- cdte solar
- metal ion
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- 238000000034 method Methods 0.000 title claims abstract description 42
- 230000007547 defect Effects 0.000 title abstract description 11
- 239000010409 thin film Substances 0.000 title abstract description 10
- 229910021645 metal ion Inorganic materials 0.000 claims abstract description 44
- 230000008569 process Effects 0.000 claims abstract description 8
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- 238000012544 monitoring process Methods 0.000 claims abstract description 5
- 238000007689 inspection Methods 0.000 claims abstract description 4
- 229910004613 CdTe Inorganic materials 0.000 claims abstract 15
- 238000007598 dipping method Methods 0.000 claims description 5
- 238000000399 optical microscopy Methods 0.000 claims description 5
- 150000002500 ions Chemical class 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 230000000007 visual effect Effects 0.000 abstract description 3
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 description 60
- 238000005286 illumination Methods 0.000 description 8
- WUPHOULIZUERAE-UHFFFAOYSA-N 3-(oxolan-2-yl)propanoic acid Chemical compound OC(=O)CCC1CCCO1 WUPHOULIZUERAE-UHFFFAOYSA-N 0.000 description 6
- 229910052980 cadmium sulfide Inorganic materials 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 229910021592 Copper(II) chloride Inorganic materials 0.000 description 4
- YKYOUMDCQGMQQO-UHFFFAOYSA-L cadmium dichloride Chemical compound Cl[Cd]Cl YKYOUMDCQGMQQO-UHFFFAOYSA-L 0.000 description 4
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 4
- 238000011179 visual inspection Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- QTMDXZNDVAMKGV-UHFFFAOYSA-L copper(ii) bromide Chemical compound [Cu+2].[Br-].[Br-] QTMDXZNDVAMKGV-UHFFFAOYSA-L 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- -1 AgCl3 Chemical compound 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 229910021590 Copper(II) bromide Inorganic materials 0.000 description 1
- VMQMZMRVKUZKQL-UHFFFAOYSA-N Cu+ Chemical compound [Cu+] VMQMZMRVKUZKQL-UHFFFAOYSA-N 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 1
- DBVJJBKOTRCVKF-UHFFFAOYSA-N Etidronic acid Chemical compound OP(=O)(O)C(O)(C)P(O)(O)=O DBVJJBKOTRCVKF-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910002666 PdCl2 Inorganic materials 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical class OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- 229910019029 PtCl4 Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000002800 charge carrier Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 229910000366 copper(II) sulfate Inorganic materials 0.000 description 1
- DOBRDRYODQBAMW-UHFFFAOYSA-N copper(i) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005401 electroluminescence Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- 229910001463 metal phosphate Inorganic materials 0.000 description 1
- 150000002739 metals Chemical group 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- HBVFXTAPOLSOPB-UHFFFAOYSA-N nickel vanadium Chemical compound [V].[Ni] HBVFXTAPOLSOPB-UHFFFAOYSA-N 0.000 description 1
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 1
- 238000005424 photoluminescence Methods 0.000 description 1
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007761 roller coating Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- ADZWSOLPGZMUMY-UHFFFAOYSA-M silver bromide Chemical compound [Ag]Br ADZWSOLPGZMUMY-UHFFFAOYSA-M 0.000 description 1
- 229910000161 silver phosphate Inorganic materials 0.000 description 1
- 229910000367 silver sulfate Inorganic materials 0.000 description 1
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(I) nitrate Inorganic materials [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- FBEIPJNQGITEBL-UHFFFAOYSA-J tetrachloroplatinum Chemical compound Cl[Pt](Cl)(Cl)Cl FBEIPJNQGITEBL-UHFFFAOYSA-J 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor 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
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1828—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe
- H01L31/1836—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe comprising a growth substrate not being an AIIBVI compound
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
- H02S50/10—Testing of PV devices, e.g. of PV modules or single PV cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
- H01L22/24—Optical enhancement of defects or not directly visible states, e.g. selective electrolytic deposition, bubbles in liquids, light emission, colour change
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present application relates to a method for process monitoring and inspection ofCdTethin film solar cellproduction process in order to visually identify defects induced by previous process steps.
- CdTe solar cell has the following structure: on a glass substrate, a transparent conducting oxide layer (TCO) is deposited as front contact.
- TCO transparent conducting oxide layer
- the TCO layer can include a high resistive buffer layer which helps to minimize the shunting effect in solar cell.
- CdS cadmium sulfide
- CdTe cadmium telluride
- a metal layer e.g. of molybdenum, nickel vanadium, tantalum, titanium, wolfram, gold or any composition or compound comprising one of these elements, is applied to collect the charge carriers. This structure is called superstrate configuration.
- thin film CdTe solar cell production process comprises further process steps, like CdCl 2 activation and /or CuCl 2 treatment.
- Invisible defects like pin-holes, particles and agglomerates, can be induced by all steps of thin film CdTe solar cell production process. Defects can result in shunting and /or reduction of power of the CdTe thin film solar cell.
- State of the art methods for measuring and identifying shunting effects are current –voltage characteristics and /or electro-and photoluminescence measurements. These methods are either limitedto thin film CdTe solar cells after completing all process steps or small sizes of CdTe solar cell. Furthermore, no correlation to causing process steps can be drawn by results of the before mentioned measuring methods.
- the object of the present invention is to provide a method for process monitoring and inspection of CdTe thin film solar cell production process, wherein this method enables visual identification of defects (e.g. pin-holes, particles, agglomerates) and correlation to previous process steps.
- defects e.g. pin-holes, particles, agglomerates
- the method according to the present application comprises the steps of providing a semi-finished CdTe solar cell, applying a metal ion solution to a CdTe surface and simultaneously illuminate the semi-finished CdTe solar cell, removingmetal ion solution from the semi-finished CdTe solar cell and visually inspecting the metal ion solution treated semi-finished CdTe solar cell by a human operator and /or optical microscopy.
- the semi-finished CdTe solar cell includes a CdS layer and a CdTe layer, wherein a surface of the CdTe layer opposite to the CdS layer forms thesurface of the semi-finished CdTe solar cell.
- the semi-finished CdTe solar cell further comprises a substrate and a front contact layer or a front contact layer sequence as known from the prior art.
- the CdS layer, the CdTe layerand the front contact layer or layer sequence are formed by methods known from the prior art.
- the metal ion solution may be applied to the surface of the semi-finished CdTe solar cell byprocesses known from the prior art such as, but not limited to:
- the metal ion solution may be anaqueous solution of metal salts, for instance metal chlorides, metal sulfates, metal nitrates, metal phosphates, metal halogenides and metal pseudo halogenides such as CuCl 2 , AgCl 3 , PdCl 2 , PtCl 4 , CuSO 4 , Ag 2 SO 4 , Cu (NO 3 ) 2 , AgNo 3 , Cu 3 (PO 4 ) 2 , Ag 3 PO 4 , CuBr 2 , AgBr, CuI or CuCN.
- metal salts for instance metal chlorides, metal sulfates, metal nitrates, metal phosphates, metal halogenides and metal pseudo halogenides such as CuCl 2 , AgCl 3 , PdCl 2 , PtCl 4 , CuSO 4 , Ag 2 SO 4 , Cu (NO 3 ) 2 , AgNo 3 , Cu 3 (PO 4 ) 2 , Ag 3 PO 4 , Cu
- the metal ion solution may further comprise complexing agents, for example ammonia solution, sodium thiosulfate solution, potassium cyanide solution, ethylenediamine, ethylenediamintetraacetic acid, phosphonates or 1-hydroxyethylidene-1, 1diphosphonic acid.
- the metal ion solution may additionally further contain diluted hydrochloric acid or phosphoric acid.
- the concentration of metal ions in the metal ion solution may be in the range between 0, 1 and 50 mmol, preferably between 1 and 10 mmol.
- a first time period, for which the metal ion solution is present on the surface of the semi-finished CdTe solar cell, for instance the first time period, for which the semi-finished CdTe solar cell (or the surface of the semi-finished CdTe solar cell) is dipped into the metal ion solution may be in the range between 5 and 300 seconds, preferably between 30 and 60 seconds.
- temperature of the semi-finished CdTe solar cell is controlled to be in the range between 15 °C and 80 °C duringthe time period, the metal ion solution is applied to the surface of semi-finished CdTe solar cells.
- the semi-finished CdTe solar cell issimultaneously illuminatedfor a second time period while the metal ion solution is present on the surface of the semi-finished CdTe solar cell.
- the second time period for which the semi-finished CdTe solar cell is simultaneously illuminated, is a time period between the beginning of the step of applying the metal ion solution and the end of the step (according to the first time period) before removing the metal ion solution.
- the second time period may be equal to the first time period, i.e.
- the semi-finished CdTe solar cell is illuminated the whole time the metal ion solution is present at least at the surface of the semi-finished CdTe solar cell, or may be shorter than the first time period, i.e. only a part of the duration of the first time period, at least half of the first time period.
- Illumination generates electron-hole pairs, which will be separated at the pn-junction by the inherent electric field of the CdTe solar cell.
- generated electrons can move along microshunts to the surface of the semi-finished CdTe solar cell. Reaction of electrons and metal ions at the surface of the semi-finished CdTe solar cells results in galvanic deposition of metals on the surface of the semi-finished CdTe solar cell, which will bevisibleat the location of present microshunts.
- “Simultaneously illumination” means an illumination which is more than the illumination due to ambient light being present during the metal ion solution treatment.
- the “simultaneously illumination” is provided additionally to these lighting conditions by an illumination source and provides an additional light with anilluminance (luminous flux per unit area) in the range of 5000 to 200000 lx.
- the light the semi-finished CdTe solar cell is simultaneously illuminated with has a wavelength in the absorption region of the CdTe solar cell, and preferably in the range between 300 to 900 nm.
- the metal ion solution may be removed from the surface of the semi-finished CdTe solar cell by removing the semi-finished CdTe solar cell from the metal ion solution held in a container and /or by blowing, rinsing with a cleaning solution, drying or a combination thereof, or by other processes known from the prior art.
- Visual inspection may be carried out bya human operator and /or optical microscopy with or without combination with image analyzing systems enabling identification of defect structures andcorrelation tocausing process steps.
- method according to the present application is suitable for monitoring CdTe thin film solar cell production process and enables visual identification of defects and efficient problem-solving by limitation to possible causing process steps.
- Fig. 1 schematically shows an exemplary process sequence of the method according to the present application.
- Fig. 2 schematically shows an embodiment of the method according to the present application, wherein application of the metal ion solution is carried out by dipping the semi-finished CdTe solar cell into the metal ion solution while simultaneously illuminating, following steps S40 and S50.
- Fig. 1 shows a process sequence of the method according to the present application.
- the semi-finished CdTe solar cell with the surface as described above is provided in step S10.
- themetal ion solution is applied to the surface of the semi-finished CdTe solar cell.
- the semi-finished CdTe solar cell is simultaneously illuminated (step S30) while the metal ion solution is present on the surface of the semi-finished CdTe solar cell.
- the metal ion solution was present on the surface of the semi-finished CdTe solar cell, it will be removed in step S40.
- visual inspection of the surface of the metal ion solution treated semi-finished CdTe solar cell is performed by a human operator and /or optical microscopy (step S50) .
- Fig. 2 an exemplary embodiment of the method according to the present application is shown schematically, wherein application of a metal ion solution (step S20) is carried out by dipping the semi-finished CdTe solar cell (10) having a surface (11) into the metal ion solution (15) while simultaneously illuminating (step S30) by anillumination source (14) .
- the metal ion solution (15) comprises 1 mmol CuCl 2 solution, corresponding to 134.45 mg CuCl 2 diluted in 1 l DI-water (deionized water) and is held in a container (12) .
- the semi-finished CdTe solar cell supported by a component (13) , for instance a holder with a clamp, is dipped into the metal ion solution (15) for 60 s and simultaneously illuminated for the whole time, the semi-finished CdTe solar cell is dipped in the metal ion solution, whereby temperature of the metal ion solution and the semi-finished CdTe solar cell is about 25 –30 °C.
- the illumination source (14) a halogen lamp with an illuminance of150000 lx (corresponding to a lamp with a power of 400 W, 8548 lm luminous flux and luminous colourof 2900 K) is used forilluminating the semi-finished CdTe solar cell (10) while it is dipped into the metal ion solution (15) .
- the metal ion solution is removed from the semi-finished CdTe solar cell (step S40) for instance by a rinsing and drying device (20) according to state of the art prior to visual inspection (step S50) .
- the following visual inspection (S50) of the surface (11) of the semi-finished CdTe solar cell (10) is carried out by a human operator and /or optical microscopy.
- the illuminating source (14) is arranged such that the light emitted by the illuminating source (14) impinges on the surface (11) of the semi-finished CdTe solar cell (10) .
- this is only one exemplary arrangement of the illuminating unit.
- the semi-finished CdTe solar cell may nevertheless be illuminated on the sunny side in any case, i.e. on the transparent substrate.
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Abstract
A method involves process monitoring and inspection of CdTe thin film solar cell (10) production process in order to visually identify defects induced by previous process steps. Metal ion solution (15) treatment of semi-finished CdTe thin film solar cell (10) in combination with simultaneously illuminating the surface of the semi-finished CdTe solar cell (10) enables visual identification of defects and correlation to previous process steps.
Description
Field of Invention
The present application relates to a method for process monitoring and inspection ofCdTethin film solar cellproduction process in order to visually identify defects induced by previous process steps.
Description of Related Arts
State of the art, CdTe solar cell has the following structure: on a glass substrate, a transparent conducting oxide layer (TCO) is deposited as front contact. The TCO layer can include a high resistive buffer layer which helps to minimize the shunting effect in solar cell. On this, a layer of cadmium sulfide (CdS) and on top of that, a layer of cadmium telluride (CdTe) are deposited. Finally a metal layer, e.g. of molybdenum, nickel vanadium, tantalum, titanium, wolfram, gold or any composition or compound comprising one of these elements, is applied to collect the charge carriers. This structure is called superstrate configuration.
State of the Art thin film CdTe solar cell production process comprises further process steps, like CdCl2 activation and /or CuCl2 treatment. Invisible defects, like pin-holes, particles and agglomerates, can be induced by all steps of thin film CdTe solar cell production process. Defects can result in shunting and /or reduction of power of the CdTe thin film solar cell. State of the art methods for measuring and identifying shunting effects are current –voltage characteristics and /or electro-and photoluminescence measurements. These methods are either limitedto thin film CdTe solar cells after completing all process steps or small sizes of CdTe solar cell. Furthermore, no correlation to causing process steps can be drawn by results of the before mentioned measuring methods.
Summary of the Present Invention
The object of the present invention is to provide a method for process monitoring and inspection of CdTe thin film solar cell production process, wherein this method enables visual identification of defects (e.g. pin-holes, particles, agglomerates) and correlation to previous process steps.
This object is achieved by the method according to claim 1. Advantageous embodiments are disclosed in the dependent sub-claims.
The method according to the present application comprises the steps of providing a semi-finished CdTe solar cell, applying a metal ion solution to a CdTe surface and simultaneously illuminate the semi-finished CdTe solar cell, removingmetal ion solution from the semi-finished CdTe solar cell and visually inspecting the metal ion solution treated semi-finished CdTe solar cell by a human operator and /or optical microscopy. The semi-finished CdTe solar cell includes a CdS layer and a CdTe layer, wherein a surface of the CdTe layer opposite to the CdS layer forms thesurface of the semi-finished CdTe solar cell. The semi-finished CdTe solar cell further comprises a substrate and a front contact layer or a front contact layer sequence as known from the prior art. The CdS layer, the CdTe layerand the front contact layer or layer sequence are formed by methods known from the prior art.
The metal ion solution may be applied to the surface of the semi-finished CdTe solar cell byprocesses known from the prior art such as, but not limited to:
- Dipping the semi-finished CdTe solar cell (or the surface of the semi-finished CdTesolar cell) into the metal ion solution held in a container,
- Spraying,
- Spin coating,
- Sponge roller coating, etc.
The metal ion solution may be anaqueous solution of metal salts, for instance metal chlorides, metal sulfates, metal nitrates, metal phosphates, metal halogenides and metal pseudo halogenidessuch as CuCl2, AgCl3, PdCl2, PtCl4, CuSO4, Ag2SO4, Cu (NO3) 2, AgNo3, Cu3 (PO4) 2, Ag3PO4, CuBr2, AgBr, CuI or CuCN. The metal ion solution may further comprise complexing agents, for example ammonia solution, sodium thiosulfate solution, potassium cyanide solution, ethylenediamine, ethylenediamintetraacetic acid, phosphonates or 1-hydroxyethylidene-1, 1diphosphonic acid. The metal ion solution may additionally further contain diluted hydrochloric acid or phosphoric acid.
The concentration of metal ions in the metal ion solution may be in the range between 0, 1 and 50 mmol, preferably between 1 and 10 mmol. A first time period, for which the metal ion solution is present on the surface of the semi-finished CdTe solar cell, for instance the first time period, for which the semi-finished CdTe solar cell (or the surface of the semi-finished CdTe solar cell) is dipped into the metal ion solution, may be in the range between 5 and 300 seconds, preferably between 30 and 60 seconds.
Furthermore, temperature of the semi-finished CdTe solar cell is controlled to be in the range between 15 ℃ and 80 ℃ duringthe time period, the metal ion solution is applied to the surface of semi-finished CdTe solar cells.
According to the present application, the semi-finished CdTe solar cell issimultaneously illuminatedfor a second time period while the metal ion solution is present on the surface of the semi-finished CdTe solar cell. The second time period, for which the semi-finished CdTe solar cell is simultaneously illuminated, is a time period between the beginning of the step of applying the metal ion solution and the end of the step (according to the first time period) before removing the metal ion solution. The second time period may be equal to the first time period, i.e. the semi-finished CdTe solar cell is illuminated the whole time the metal ion solution is present at least at the surface of the semi-finished CdTe solar cell, or may be shorter than the first time period, i.e. only a part of the duration of the first time period, at least half of the first time period.
Illumination generates electron-hole pairs, which will be separated at the pn-junction by the inherent electric field of the CdTe solar cell. In case of present microshunts, caused by pin-holes or other defects induced by previous processsteps, for instance CdS /CdTe deposition or CdCl2 activation treatment, generated electrons can move along microshunts to the surface of the semi-finished CdTe solar cell. Reaction of electrons and metal ions at the surface of the semi-finished CdTe solar cells results in galvanic deposition of metals on the surface of the semi-finished CdTe solar cell, which will bevisibleat the location of present microshunts.
“Simultaneously illumination” means an illumination which is more than the illumination due to ambient light being present during the metal ion solution treatment. The “simultaneously illumination” is provided additionally to these lighting conditions by an illumination source and provides an additional light with anilluminance (luminous flux per unit area) in the range of 5000 to 200000 lx.
The light the semi-finished CdTe solar cell is simultaneously illuminated with has a wavelength in the absorption region of the CdTe solar cell, and preferably in the range between 300 to 900 nm.
The metal ion solution may be removed from the surface of the semi-finished CdTe solar cell by removing the semi-finished CdTe solar cell from the metal ion solution held in a container and /or by blowing, rinsing with a cleaning solution, drying or a combination thereof, or by other processes known from the prior art.
Visual inspection may be carried out bya human operator and /or optical microscopy with or without combination with image analyzing systems enabling identification of defect structures andcorrelation tocausing process steps.
Therefore, method according to the present application is suitable for monitoring CdTe thin film solar cell production process and enables visual identification of defects and efficient problem-solving by limitation to possible causing process steps.
Fig. 1 schematically shows an exemplary process sequence of the method according to the present application.
Fig. 2 schematically shows an embodiment of the method according to the present application, wherein application of the metal ion solution is carried out by dipping the semi-finished CdTe solar cell into the metal ion solution while simultaneously illuminating, following steps S40 and S50.
Detailed Description of the Preferred Embodiments
The methodaccording to the invention is explained in the following exemplary embodiment, wherein the figures are not intended to imply a restriction to the shown embodiments.
Fig. 1 shows a process sequence of the method according to the present application. At the beginning, the semi-finished CdTe solar cell with the surface as described above is provided in step S10. In a next step S20, themetal ion solution is applied to the surface of the semi-finished CdTe solar cell. The semi-finished CdTe solar cell is simultaneously illuminated (step S30) while the metal ion solution is present on the surface of the semi-finished CdTe solar cell. After the metal ion solution was present on the surface of the semi-finished CdTe solar cell, it will be removed in step S40. Subsequently to step S40, visual inspection of the surface of the metal ion solution treated semi-finished CdTe solar cell is performed by a human operator and /or optical microscopy (step S50) .
In Fig. 2, an exemplary embodiment of the method according to the present application is shown schematically, wherein application of a metal ion solution (step S20) is carried out by dipping the semi-finished CdTe solar cell (10) having a surface (11) into the metal ion solution (15) while simultaneously illuminating (step S30) by anillumination source (14) . The metal ion solution (15) comprises 1 mmol CuCl2 solution, corresponding to 134.45 mg CuCl2 diluted in 1 l DI-water (deionized water) and is held in a container (12) . The semi-finished CdTe solar cell,
supported by a component (13) , for instance a holder with a clamp, is dipped into the metal ion solution (15) for 60 s and simultaneously illuminated for the whole time, the semi-finished CdTe solar cell is dipped in the metal ion solution, whereby temperature of the metal ion solution and the semi-finished CdTe solar cell is about 25 –30 ℃. Further, the illumination source (14) , a halogen lamp with an illuminance of150000 lx (corresponding to a lamp with a power of 400 W, 8548 lm luminous flux and luminous colourof 2900 K) is used forilluminating the semi-finished CdTe solar cell (10) while it is dipped into the metal ion solution (15) . The metal ion solution is removed from the semi-finished CdTe solar cell (step S40) for instance by a rinsing and drying device (20) according to state of the art prior to visual inspection (step S50) . The following visual inspection (S50) of the surface (11) of the semi-finished CdTe solar cell (10) is carried out by a human operator and /or optical microscopy.
In the examples shown in Figs. 2, the illuminating source (14) is arranged such that the light emitted by the illuminating source (14) impinges on the surface (11) of the semi-finished CdTe solar cell (10) . However, this is only one exemplary arrangement of the illuminating unit. The semi-finished CdTe solar cell may nevertheless be illuminated on the sunny side in any case, i.e. on the transparent substrate.
The embodiments of the invention described in the foregoing description are examples given by way of illustration and the invention is nowise limited thereto. Any modification, variation and equivalent arrangement as well as combinations of embodiments should be considered as being included within the scope of the invention.
Reference numerals
10 semi-finished CdTe solar cell
11 the surface of the semi-finished CdTe solar cell
12 container
13 component for dipping
14 illumination source
15 metal ion solution
20 rinsing and drying device
Claims (7)
- Method for process monitoring and inspection of CdTethin film solar cell productionprocess, comprising the steps:a) providing a semi-finished CdTe solar cell including a CdS layer and a CdTe layer, wherein asurface of the CdTelayer opposite to the CdS layer formsthe surface of the semi-finished CdTe solar cell,b) applyinga metal ion solution to the surface of the semi-finished CdTe solar cellandc) simultaneously to b) illuminating the semi-finished CdTe solar cell,d) removing the metal ion solution from the semi-finished CdTe solar cell ande) visually inspectingthe surface of the semi-finished CdTe solar cell by a human operator and /or optical microscopy after removing the metal ion solution.
- Method according to claim 1, characterized in that themetal ion solution is applied by dipping the semi-finished CdTe solar cell intothe metal ion solution.
- Method according to claim 1, characterized in that the concentration of metal ions in the metal ion solution may be in the range between 0.1 and 50 mmol.
- Method according to claim 1, characterised in that the light the semi-finished CdTe solar cell isilluminated with has a wavelength in the absorption region of the CdTe solar cell.
- Method according to claim 4, characterized in that the wavelength of the light is in the range from 400 to 900 nm.
- Method according to claim 1, characterized in that the time period for application of the metal ion solution lies in the range between 5 seconds to 5 minutes.
- Method according to any one of the preceding claims, characterized in that a temperature of the semi-finished CdTe solar cell and the metal ion solution isin the range between 15 to 80℃during the time period, the metal ion solution is applied to the semi-finished CdTe solar cell.
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| CN201680074109.7A CN108604616B (en) | 2016-12-27 | 2016-12-27 | Method for visualizing defects in semi-finished CdTe thin film solar cell |
| PCT/CN2016/112397 WO2018119675A1 (en) | 2016-12-27 | 2016-12-27 | Method for visualizing defects in a semi-finished cdte thin film solar cell |
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| PCT/CN2016/112397 WO2018119675A1 (en) | 2016-12-27 | 2016-12-27 | Method for visualizing defects in a semi-finished cdte thin film solar cell |
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| JPH10275840A (en) * | 1997-03-31 | 1998-10-13 | Toshiba Corp | Defect evaluation method and device of insulating film |
| JP2000082727A (en) * | 1998-09-04 | 2000-03-21 | Toshiba Corp | Method for evaluating fault of insulating film |
| US6174727B1 (en) * | 1998-11-03 | 2001-01-16 | Komatsu Electronic Metals, Co. | Method of detecting microscopic defects existing on a silicon wafer |
| JP2005166705A (en) * | 2003-11-28 | 2005-06-23 | Canon Inc | Defect detecting method of insulating film or semiconductor film |
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|---|---|---|---|---|
| US4144139A (en) * | 1977-11-30 | 1979-03-13 | Solarex Corporation | Method of plating by means of light |
| JPH11274257A (en) * | 1998-03-18 | 1999-10-08 | Shin Etsu Handotai Co Ltd | Method of evaluating defect of semiconductor crystal |
| CN101257059B (en) * | 2007-11-30 | 2011-04-13 | 无锡尚德太阳能电力有限公司 | Method for electrochemical depositing solar cell metallic electrode |
| JP6094898B2 (en) * | 2014-05-15 | 2017-03-15 | 信越半導体株式会社 | Contamination assessment method |
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- 2016-12-27 WO PCT/CN2016/112397 patent/WO2018119675A1/en active Application Filing
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10275840A (en) * | 1997-03-31 | 1998-10-13 | Toshiba Corp | Defect evaluation method and device of insulating film |
| JP2000082727A (en) * | 1998-09-04 | 2000-03-21 | Toshiba Corp | Method for evaluating fault of insulating film |
| US6174727B1 (en) * | 1998-11-03 | 2001-01-16 | Komatsu Electronic Metals, Co. | Method of detecting microscopic defects existing on a silicon wafer |
| JP2005166705A (en) * | 2003-11-28 | 2005-06-23 | Canon Inc | Defect detecting method of insulating film or semiconductor film |
| CN106252432A (en) * | 2016-09-28 | 2016-12-21 | 中山瑞科新能源有限公司 | A kind of cadmium telluride preparation method of solar battery reducing defect concentration |
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| CN108604616A (en) | 2018-09-28 |
| CN108604616B (en) | 2023-03-24 |
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