WO2025201520A1 - Procédé de nettoyage de surface de couche de film mince à base de cdte après traitement d'activation et procédé de formation de dispositif photovoltaïque - Google Patents

Procédé de nettoyage de surface de couche de film mince à base de cdte après traitement d'activation et procédé de formation de dispositif photovoltaïque

Info

Publication number
WO2025201520A1
WO2025201520A1 PCT/CN2025/085761 CN2025085761W WO2025201520A1 WO 2025201520 A1 WO2025201520 A1 WO 2025201520A1 CN 2025085761 W CN2025085761 W CN 2025085761W WO 2025201520 A1 WO2025201520 A1 WO 2025201520A1
Authority
WO
WIPO (PCT)
Prior art keywords
cdte
thin film
film layer
based thin
solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2025/085761
Other languages
English (en)
Inventor
Christian DROST
Shou PENG
Bin Xu
Yong Dong
Congxiao WANG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Triumph International Engineering Co Ltd
Original Assignee
China Triumph International Engineering Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China Triumph International Engineering Co Ltd filed Critical China Triumph International Engineering Co Ltd
Publication of WO2025201520A1 publication Critical patent/WO2025201520A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • H10F71/125—The active layers comprising only Group II-VI materials, e.g. CdS, ZnS or CdTe
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
    • B08B3/04—Cleaning involving contact with liquid
    • B08B3/08—Cleaning involving contact with liquid the liquid having chemical or dissolving effect

Definitions

  • the present invention relates to a method for cleaning a surface of a CdTe-based thin film layer after an activation treatment, for instance a CdTe-based thin film absorber layer of a photovoltaic device.
  • the present invention further relates to a method for forming a photovoltaic device.
  • CdTe-based thin film layers are widely used in different device, for instance in photovoltaic devices as an absorber layer.
  • a CdTe-based thin film layer according to the invention is any layer comprising cadmium and tellurium and may comprise other elements in an alloy or as a doping element.
  • the following alloys should be understood as a CdTe-based layer: CdSe x Te 1-x , CdS x Te 1-x CdZn x Te 1-x , CdMg x Te 1-x , CdMn x Te 1-x , CdHg x Te 1-x , wherein x may vary between 0 (zero) and a value smaller 1 (0 ⁇ x ⁇ 1) .
  • Doping elements may be, for instance, Cu, As, Sb, N, Ag, Li, Na, P.
  • CdTe-based thin film layers are usually formed by physical vapour deposition, e.g. by sputtering, thermal evaporation or sublimation, for instance close-space sublimation (CSS) .
  • a process called activation is performed after depositing the CdTe-based thin film layer.
  • This process comprises a thermal treatment usually under presence of an activation agent, for instance CdCl 2 , and results in an intermixing of different material layers, if the CdTe-based thin film layer is formed as a layer stack comprising different materials like, for instance, CdSe and CdTe, thereby forming a defined concentration gradient of the different elements within the CdTe-based thin film layer.
  • defects within the CdTe-based thin film layer are at least partially cured and a diffusion of doping materials may take place.
  • the activation treatment leaves Cd-based residues on the surface of the CdTe-based thin film layer, which have to be removed before further processing a semi-finished product the CdTe-based thin film layer being a part of.
  • the CdTe-based thin film layer is cleaned after activation with an oxidizing agent, like a nitric/phosphoric-based acid (NP etch) or bromine in methanol (BM etch) as described in US 2014/0273407 A1.
  • an oxidizing agent like a nitric/phosphoric-based acid (NP etch) or bromine in methanol (BM etch) as described in US 2014/0273407 A1.
  • NP etch nitric/phosphoric-based acid
  • BM etch bromine in methanol
  • a drawback of some of these cleaning agents is that the structure and stochiometric composition of the CdTe-based thin film layer is changed in a region near the surface, and that the surface is oxidized or reduced which may be disadvantageous for further processing, for instance for depositing a back contact layer on the CdTe-based thin film layer.
  • the object is therefore to provide a further method for cleaning a surface of a CdTe-based thin film after an activation treatment, wherein the further method may reduce some of the negative effects of the methods according to the state of the art.
  • the object is further to provide a method for forming a photovoltaic device having improved efficiency.
  • a first aspect of the invention provides a method for cleaning a surface of a CdTe-based thin film layer after an activation treatment.
  • This method comprises a step of forming a CdTe-based thin film layer, a step of performing an activation treatment under the presence of an activation agent, and a step of cleaning the CdTe-based thin film layer with a solution comprising methanesulfonic acid (CH 3 SO 3 H) .
  • the steps of forming a CdTe-based thin film layer and of performing an activation treatment are known from the state of the art.
  • an activation agent known compounds like CdCl 2 or other halogenides may be used as known from the state of the art.
  • the activation treatment usually comprises a temperature treatment with temperatures in the range of 350°C to 450°C.
  • the solution comprising methanesulfonic acid removes residues of the activation agent resulting from the activation treatment, wherein also Cd-based residues are removed.
  • the method according to the invention provides some advantages:
  • the solution comprising methanesulfonic acid forms a hydrophobic absorber surface after cleaning, which is advantageous for further processing a semi-finished product comprising the CdTe-based thin film layer.
  • the solution comprising methanesulfonic acid etches the CdTe-based material of the CdTe-based thin film layer, in particular along the grain boundaries, less.
  • the solution comprising methanesulfonic acid is not corrosive and not toxic, does not comprise aggressive chloride ions and does not form gaseous aggressive or toxic compositions as a solution comprising hydrochloric acid produces.
  • the solution comprising methanesulfonic acid is bio-degradable. Therefore, requirements to processing equipment with respect to corrosion and toxicity can be relaxed. Furthermore, the solution comprising methanesulfonic acid does not oxidize the surface of the CdTe-based thin film layer, i.e. the stoichiometry of the CdTe-based thin film layer is not changed at its surface.
  • the solution comprising methanesulfonic acid is generated by solving isolated methanesulfonic acid in an aqueous or an organic solution. That is, isolated methanesulfonic acid is dissolved in water or in an organic compound, e.g. ethanol, tetrahydrofuran, toluol or others, or in a mixture of water and an organic compound.
  • an organic compound e.g. ethanol, tetrahydrofuran, toluol or others
  • the use of short-chain alcohols allows a fast drying of the surface of the CdTe-based thin film layer after cleaning or a self-limitation of the residence time of the solution on the CdTe-based thin film layer.
  • Long-chain or branched alcohols e.g.
  • the isolated methanesulfonic acid is dissolved in a solution comprising further compounds.
  • the solution comprises only methanesulfonic acid and water and/or an alcohol.
  • the solution comprising methanesulfonic acid comprises methanesulfonic acid in the range of 0.1 %to 10 %, in particular in the range between 1 %and 6 %for longer residence times of the solution comprising methanesulfonic acid on the surface of the CdTe-based thin film layer and between 5 %and 10 %for shorter residence times as useful in industrial applications.
  • the step of cleaning the CdTe-based thin film layer with a solution comprising methanesulfonic acid is performed for a time period in the range of 10 s to 60 s, in particular in the range of 10 s to 30 s for use in industrial applications and in the range of 20 s to 60 s in other applications.
  • the CdTe-based thin film layer has a temperature in the range of 20°C to 40°Cduring the step of cleaning the CdTe-based thin film layer, in particular in the range of 20°C to 30°C. Since the activation treatment is performed usually at elevated temperatures, the CdTe-based thin film layer should cool down before performing the cleaning step.
  • the solution comprising methanesulfonic acid is applied to the CdTe-based thin film layer by spraying, rinsing or roller-coating, or by dipping the CdTe-based thin film layer at least with its surface to be cleaned into the solution. All of these methods are known to a person skilled in the art.
  • a further aspect of the invention refers to a method for forming a photovoltaic device comprising the steps of providing a substrate comprising a first electrode, performing the above described method for cleaning a surface of a CdTe-based thin film layer after an activation treatment, wherein the CdTe-based thin film layer is formed on the substrate, and forming a second electrode on the CdTe-based thin film layer after performing the method for cleaning the surface of a CdTe-based thin film layer after an activation treatment.
  • the method comprises providing a substrate comprising a first electrode, forming a CdTe-based thin film layer on the first electrode, performing an activation treatment under the presence of an activation agent, cleaning the CdTe-based thin film layer with a solution comprising methanesulfonic acid after activation as described above, and forming a second electrode on the CdTe-based thin film layer, wherein the steps are performed in the given sequence. Furthermore, several cleaning steps, temperature treatment steps and further intermediate steps may be performed between different of the mentioned steps.
  • the method according to the invention allows a very good removal of activation residuals and a reduced negative effect on the structure and stoichiometry of the CdTe-based thin film layer at the cleaned surface. It further provides a hydrophobic surface of the CdTe-based thin film layer being favorable for further processing, in particular for forming the second electrode on that surface.
  • the CdTe-based thin film layer is a CdSe x Te 1-x layer which may have a selenium concentration gradient over the thickness of the CdSe x Te 1-x layer, wherein the selenium content, i.e. the selenium concentration, near the first electrode is higher than that near the second electrode, at least directly after forming the CdTe-based thin film layer.
  • a layer may be formed by sequentially depositing a CdSe layer and a CdTe layer and then forming the CdSe x Te 1-x layer by a temperature treatment resulting in interdiffusion and alloying.
  • Other methods for forming such a layer may include alternatively depositing CdSe and CdTe layers, wherein a CdSe layer is formed first at the first electrode and a CdTe layer is formed last and wherein the thickness of the individual CdSe layers may decrease with their ordinal number and/or the thickness of the individual CdTe layers may increase with their ordinal number.
  • a further method is to use different source compositions during forming of the CdTe-based thin film layer in order to achieve the mentioned selenium concentration gradient. The cleaning of the CdSe x Te 1-x layer with a solution comprising methanesulfonic acid after activation does not significantly change this concentration gradient, at least with respect to selenium bound within the CdSe x Te 1-x crystal structure.
  • Figure 1 shows an embodiment of the method for forming a photovoltaic device including an embodiment of the method for cleaning a surface of a CdTe-based thin film layer after an activation treatment according to the present invention.
  • a substrate with a first electrode on it is provided.
  • a CdTe-based thin film layer is then formed on the first electrode, for instance by closed-space sublimation (CSS) , in a second step S20.
  • This step may also comprise a temperature treatment subsequent to depositing one or more CdTe-based thin film layers in order to support intermixing of different layers and removing crystal defects within the deposited layer (s) .
  • an activation treatment is performed under the presence of an activation agent, e.g.
  • step S40 the surface of the CdTe-based thin film layer is cleaned using a solution comprising methanesulfonic acid in step S40.
  • the cleaning solution is formed from dissolving isolated methanesulfonic acid in water and comprises 6 %methanesulfonic acid.
  • the cleaning step is performed for 30 s, wherein the surface to be cleaned of the CdTe-based thin film layer is dipped into the solution.
  • the solution comprising methanesulfonic acid has a temperature of 25°C and the CdTe-based thin film layer has a temperature of 25°C.
  • the surface of the CdTe-based thin film layer is rinsed with high-purity water, e.g. demineralized, deionized and/or distilled water.
  • high-purity water e.g. demineralized, deionized and/or distilled water.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Photovoltaic Devices (AREA)

Abstract

L'invention concerne un procédé de nettoyage d'une surface d'une couche de film mince à base de CdTe après un traitement d'activation. Le procédé comprend la formation d'une couche de film mince à base de CdTe, la réalisation d'un traitement d'activation en présence d'un agent d'activation, et le nettoyage de la couche de film mince à base de CdTe avec une solution comprenant de l'acide méthanesulfonique. En outre, l'invention concerne un procédé de formation d'un dispositif photovoltaïque comprenant le procédé de nettoyage d'une surface d'une couche de film mince à base de CdTe après un traitement d'activation.
PCT/CN2025/085761 2024-03-28 2025-03-28 Procédé de nettoyage de surface de couche de film mince à base de cdte après traitement d'activation et procédé de formation de dispositif photovoltaïque Pending WO2025201520A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202410368072.5A CN120730861A (zh) 2024-03-28 2024-03-28 活化处理后清洁CdTe基薄膜层表面的方法和形成光伏设备方法
CN202410368072.5 2024-03-28

Publications (1)

Publication Number Publication Date
WO2025201520A1 true WO2025201520A1 (fr) 2025-10-02

Family

ID=97167536

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2025/085761 Pending WO2025201520A1 (fr) 2024-03-28 2025-03-28 Procédé de nettoyage de surface de couche de film mince à base de cdte après traitement d'activation et procédé de formation de dispositif photovoltaïque

Country Status (2)

Country Link
CN (1) CN120730861A (fr)
WO (1) WO2025201520A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5045210A (en) * 1989-04-11 1991-09-03 Cuno, Incorporated Heavy metal removal process
JPH0653198A (ja) * 1992-06-03 1994-02-25 Hitachi Ltd 洗浄剤、および、これを用いた半導体基板の洗浄方法
KR20030034286A (ko) * 2001-09-28 2003-05-09 한국화학연구원 특정 중금속이온 흡착용 킬레이트 수지
CN103909090A (zh) * 2014-04-28 2014-07-09 山东大学 一种利用表面活性剂形成的水基泡沫去除土壤中重金属离子的方法
CN104425652A (zh) * 2013-08-30 2015-03-18 中国建材国际工程集团有限公司 用于生产薄膜太阳能电池的方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5045210A (en) * 1989-04-11 1991-09-03 Cuno, Incorporated Heavy metal removal process
JPH0653198A (ja) * 1992-06-03 1994-02-25 Hitachi Ltd 洗浄剤、および、これを用いた半導体基板の洗浄方法
KR20030034286A (ko) * 2001-09-28 2003-05-09 한국화학연구원 특정 중금속이온 흡착용 킬레이트 수지
CN104425652A (zh) * 2013-08-30 2015-03-18 中国建材国际工程集团有限公司 用于生产薄膜太阳能电池的方法
CN103909090A (zh) * 2014-04-28 2014-07-09 山东大学 一种利用表面活性剂形成的水基泡沫去除土壤中重金属离子的方法

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