Alkali metal post-deposition processing device and processing method for CIGS thin-film solar cell

Abstract

The invention discloses a CIGS thin film solar cell alkali metal post-deposition processing device and method, and belongs to the technical field of solar cells, the device comprises a process cavity, a PECVD device and an Ar gas inlet system, an alkali metal evaporation source and a deflection coil are arranged in the process cavity, and the method comprises the steps that firstly, an alkali metal thin film is evaporated on the surface of an absorption layer of a substrate; ar < + > ions are used for impacting the alkali metal film, the atomic energy of alkali metal is improved, and alkali metal atoms are promoted to be gathered on the front surface of the absorption layer to form an alloy layer and permeate into the CIGS grain boundary of the absorption layer. The alkali metal film is evaporated in an evaporation coating mode, the amount of alkali metal can be well controlled, and follow-up cleaning is not needed; the plasma impacts the alkali metal to greatly improve the energy of the alkali metal, so that the alkali metal more efficiently permeates into the absorption layer; the alkali metal post-treatment process can be integrated into one process, so that the process steps are reduced, the manufacturing cost is reduced, and the process flow is simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and specifically discloses an alkali metal post-deposition processing device and a processing method for a CIGS thin-film solar cell. Background Art

[0002] Thin-film solar cells are one of the most efficient solar cells with excellent stability. They are widely used in photovoltaic building integration (BIPV), household power generation, facility agriculture and other fields, and have broad application prospects. The alkali metal post-deposition treatment of CIGS (copper indium gallium selenide) solar cells refers to the deposition of a layer of alkali metal on the surface of the absorption layer after the CIGS light absorption layer is completed to improve the open circuit voltage and fill factor of CIGS solar cells.

[0003] Appropriate alkali metal post-deposition treatment can improve the surface morphology of the absorption layer, reduce the defect concentration, weaken the influence of grain boundaries, change the band structure, and increase the effective absorption density of the absorption layer to light. Figure 1 As shown: Alkali metal elements are first doped and deposited on the surface of the CIGS absorption layer, followed by heat treatment, and finally the alkali metal residues are cleaned. This method heats the surface of the CIGS to allow the alkali metal to penetrate into the CIGS grain boundary, thereby improving its grain boundary characteristics. The main problem with this method is that the process is complicated, and the steps of heating and cleaning are added, which increases the manufacturing cost. In addition, the energy of the alkali metal only by heating is low, and it is difficult to penetrate into the CIGS absorption layer. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art and provide a CIGS thin-film solar cell alkali metal post-deposition treatment device and treatment method, which utilizes highly active Ar2 plasma to activate the alkali element layer, promote alkali metal doping, and ensure that the surface alkali elements penetrate into the CIGS grain boundaries.

[0005] In order to solve the above technical problems, the present invention provides a CIGS thin-film solar cell alkali metal post-deposition processing device, comprising:

[0006] A process chamber, wherein the process chamber comprises an evaporation chamber and a plasma chamber connected to the evaporation chamber, and a chamber flap valve is provided between the evaporation chamber and the plasma chamber;

[0007] A vacuum system; comprising an exhaust system and an air intake system connected to the process chamber, for providing a vacuum environment for the process chamber;

[0008] An alkali metal evaporation source is disposed in the evaporation chamber and is used to evaporate and deposit the alkali metal onto the substrate;

[0009] A deflection coil is provided in the plasma chamber and is used to generate a linearly changing magnetic field;

[0010] A PECVD device is communicated with the plasma chamber and is used to provide plasma to the plasma chamber;

[0011] The Ar gas inlet system is connected to the PECVD device and is used to provide Ar gas.

[0012] As a further description of the present invention, the alkali metal evaporation source is a sodium sulfide evaporation source or a potassium fluoride evaporation source.

[0013] As a further description of the present invention, a plasma valve is provided between the PECVD device and the plasma chamber.

[0014] As a further description of the present invention, it also includes a conveying roller, which is arranged at the bottom of the process chamber. A substrate loading box is arranged on the conveying roller for loading and conveying the substrate.

[0015] In order to solve the above technical problems, the present invention also provides a CIGS thin-film solar cell alkali metal post-deposition treatment method, comprising the following steps:

[0016] (1) Turn on the vacuum system and evacuate the process chamber;

[0017] (2) preheating the substrate with the CIGS absorption layer to 80-90° C. and transferring it to the evaporation chamber, turning on the alkali metal evaporation source, and evaporating an alkali metal film on the surface of the CIGS absorption layer;

[0018] (3) Open the Ar gas inlet system and pass Ar into the PECVD device to generate Ar by DC glow discharge. + The plasma is introduced into the plasma chamber, the chamber flap valve is opened, and the substrate with the alkali metal film evaporated is transferred into the plasma chamber. Under the action of the deflection coil, the Ar + The plasma continuously impacts the alkali metal film, increasing the energy of the alkali metal atoms, promoting the alkali metal to aggregate on the front surface of the absorption layer to form an alloy layer and penetrate into the CIGS grain boundary.

[0019] As a further description of the present invention, in step (2), the evaporation temperature of the evaporation source is 500-700°C.

[0020] As a further description of the present invention, in step (3), the flow rate of Ar introduced into the PECVD device is 60-120 sccm, and the vacuum degree in the plasma chamber is 1.1×10 -4 ~2.5×10 -4 mbar, and the duration of plasma impact on alkali metal is 5 to 8 minutes.

[0021] The present invention also provides a method for preparing a CIGS thin-film solar cell, comprising the following steps:

[0022] (1) forming a back electrode on a substrate;

[0023] (2) depositing a Cu-Na alloy layer, a Cu-Ga alloy layer and an In layer on the back electrode in sequence to form an absorption middle layer;

[0024] (3) Spraying Se vapor onto the absorbing middle layer to form a Se layer, thereby forming an absorbing prefabricated layer;

[0025] (4) performing high-temperature selenization on the formed absorption prefabricated layer to form a CIGS absorption layer;

[0026] (5) Using the alkali metal post-deposition treatment method described in any one of claims 6 to 9, an alkali metal thin film is deposited on the CIGS absorber layer and Ar + Plasma treatment;

[0027] (6) evaporating an In2S3 buffer layer and depositing an intrinsic ZnO high-resistance layer;

[0028] (7) Deposition of AZO film on the ZnO high resistance layer

[0029] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] (1) Evaporation coating can well control the amount of alkali metal, and no subsequent cleaning is required;

[0031] (2) Plasma impact on alkali metals greatly increases the energy of alkali metals, enabling more efficient penetration of alkali metals into the absorption layer;

[0032] (3) The alkali metal post-treatment process can be integrated into one process, reducing the number of process steps, lowering the production cost, and simplifying the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The following is a flow chart of the preparation of existing CIGS thin-film solar cells;

[0034] Figure 2 It is a schematic structural diagram of an alkali metal post-deposition treatment device for a CIGS thin-film solar cell according to the present invention;

[0035] Figure 3 The figure is a flow chart of the preparation of the CIGS thin film solar cell of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] Embodiment 1:

[0038] This embodiment provides a CIGS thin-film solar cell alkali metal post-deposition processing device, such as Figure 2 As shown, including:

[0039] A process chamber, wherein the process chamber comprises an evaporation chamber 10 and a plasma chamber 20 connected to the evaporation chamber 10, an inlet flap valve 31 is provided at the inlet of the evaporation chamber 10, a chamber flap valve 32 is provided between the evaporation chamber 10 and the plasma chamber 20, and an outlet flap valve 33 is provided at the outlet of the plasma chamber 20; a conveying roller 50 is provided at the bottom of the process chamber, and a substrate loading box 60 is provided on the conveying roller 50 for loading and conveying the substrate;

[0040] A vacuum system; comprising an exhaust system 42 and an air intake system 41 connected to the process chamber, for providing a vacuum environment for the process chamber;

[0041] An alkali metal evaporation source 11 is disposed in the evaporation chamber 10 and is used to evaporate and deposit alkali metal onto the substrate. The alkali metal evaporation source 11 is a Na2S evaporation source or a KF evaporation source.

[0042] The deflection coil 21 is disposed in the plasma chamber 20 and is used to generate a linearly changing magnetic field;

[0043] A PECVD device 72 is connected to the plasma chamber 20 and is used to provide plasma for the plasma chamber. A plasma valve 73 is provided between the PECVD device 72 and the plasma chamber 20.

[0044] The Ar gas inlet system 71 is connected to the PECVD device 72 and is used to supply Ar gas to the PECVD device 72 and generate Ar by direct current glow discharge. + Highly active plasma.

[0045] Embodiment 2:

[0046] This embodiment provides a CIGS thin-film solar cell alkali metal post-deposition treatment method, using the post-deposition treatment device of the first embodiment, including the following steps:

[0047] (1) Turn on the vacuum system and evacuate the process chamber;

[0048] (2) opening the inlet flap valve 31, preheating the substrate with the CIGS absorption layer to 90° C. and transferring it to the evaporation chamber 10, turning on the Na2S evaporation source 11, setting the temperature of the evaporation source 11 to 500° C., and using the Knudsen source thermal evaporation method to evaporate a Na2S film on the surface of the absorption layer;

[0049] (3) Open the Ar gas inlet system 71, the PECVD device 72 and the plasma valve 73, and introduce Ar into the PECVD device 72 at a flow rate of 120 sccm to generate Ar by direct current glow discharge. + The highly active plasma is introduced into the plasma chamber 20, and the vacuum degree in the plasma chamber is maintained at 1.1×10-4 ~2.5×10 -4 mbar, open the chamber flap valve 32, transfer the substrate with the Na2S film deposited on it into the plasma chamber 20, and under the action of the linearly changing magnetic field generated by the deflection coil 21, the Ar + The plasma continuously impacts the Na2S film for 5 minutes, increasing the energy of Na atoms and promoting the aggregation of Na atoms on the front surface of the absorption layer to form a NaxCu1-xInSe2 alloy layer and to penetrate into the CIGS grain boundaries.

[0050] Embodiment three:

[0051] This embodiment provides a method for preparing a CIGS thin-film solar cell, the process of which is as follows: Figure 3 As shown, the following steps are included:

[0052] (1) A Mo film, a SiN layer, and a Mo film are sequentially deposited on a glass substrate by magnetron sputtering to form a back electrode;

[0053] (2) cleaning the substrate with the back electrode to remove dirt, and sequentially depositing a Cu-Na alloy layer, a Cu-Ga alloy layer, and an In layer on the back electrode by magnetron sputtering to form an absorption middle layer;

[0054] (3) using a thermal evaporation method to spray Se vapor onto the absorbing middle layer to form a Se layer, thereby forming an absorbing prefabricated layer;

[0055] (4) subjecting the prefabricated layer formed above to high-temperature selenization in a rapid selenization furnace to form a CIGS absorption layer;

[0056] (5) cleaning the substrate on which the CIGS absorption layer is made;

[0057] (6) Using the Knudsen source thermal evaporation method to evaporate a Na2S thin film on the surface of the absorption layer of the substrate; passing Ar gas into the PECVD device to generate Ar through a DC glow discharge method. + Highly active plasma, Ar + The ions impact the Na2S film, increasing the energy of Na atoms and promoting the aggregation of Na atoms on the front surface of the absorber layer to form a NaxCu1-xInSe2 alloy layer and to penetrate into the CIGS grain boundaries of the absorber layer;

[0058] (7) Evaporating an In2S3 buffer layer and then depositing an intrinsic ZnO high-resistance layer by sputtering;

[0059] (8) The AZO film layer is deposited on the high resistance layer by magnetron sputtering.

[0060] Embodiment 4:

[0061] This embodiment provides a CIGS thin-film solar cell alkali metal post-deposition treatment method, using the post-deposition treatment device of the first embodiment, including the following steps:

[0062] (1) Turn on the vacuum system and evacuate the process chamber;

[0063] (2) opening the inlet flap valve 31, preheating the substrate with the CIGS absorber layer to 80° C. and transferring it to the evaporation chamber 10, turning on the KF evaporation source 11, setting the evaporation source temperature to 700° C., and using the Knudsen source thermal evaporation method to evaporate a KF film on the surface of the absorber layer;

[0064] (3) Open the Ar gas inlet system 71, the PECVD device 72 and the plasma valve 73, and introduce Ar into the PECVD device 72 at a flow rate of 60 sccm to generate Ar by direct current glow discharge. + The highly active plasma is introduced into the plasma chamber 20, and the vacuum degree in the plasma chamber is maintained at 1.1×10 -4 ~2.5×10 -4 mbar, open the chamber flap valve 32, transfer the substrate with KF film vapor deposited into the plasma chamber 20, and under the action of the linearly changing magnetic field generated by the deflection coil 21, the Ar + The plasma continuously impacts the evaporated KF film for 8 minutes, increasing the energy of K atoms and promoting the aggregation of K atoms on the front surface of the absorption layer to form a KInSe2 layer and penetrate into the CIGS grain boundaries.

[0065] Embodiment five:

[0066] This embodiment provides a method for preparing a CIGS thin-film solar cell, comprising the following steps:

[0067] (1) A Mo film, a SiN layer, and a Mo film are sequentially deposited on a glass substrate by magnetron sputtering to form a back electrode;

[0068] (2) cleaning the substrate with the back electrode to remove dirt, and sequentially depositing a Cu-Na alloy layer, a Cu-Ga alloy layer, and an In layer on the back electrode by magnetron sputtering to form an absorption middle layer;

[0069] (3) using a thermal evaporation method to spray Se vapor onto the absorbing middle layer to form a Se layer, thereby forming an absorbing prefabricated layer;

[0070] (4) subjecting the prefabricated layer formed above to high-temperature selenization in a rapid selenization furnace to form a CIGS absorption layer;

[0071] (5) cleaning the substrate on which the CIGS absorption layer is made;

[0072] (6) Using the Knudsen source thermal evaporation method to evaporate KF thin film on the surface of the absorption layer of the substrate; passing Ar gas into the PECVD device to generate Ar by direct current glow discharge. + Highly active plasma, Ar + The ions continuously impact the KF film, increasing the energy of K atoms, promoting the aggregation of K atoms on the front surface of the absorber layer to form a KInSe2 layer and to penetrate into the CIGS grain boundaries of the absorber layer;

[0073] (7) Evaporating an In2S3 buffer layer and then depositing an intrinsic ZnO high-resistance layer by sputtering;

[0074] (8) The AZO film layer is deposited on the high resistance layer by magnetron sputtering.

[0075] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention in any form. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A CIGS thin-film solar cell alkali metal post-deposition treatment device, characterized in that: include: A process chamber, wherein the process chamber comprises an evaporation chamber and a plasma chamber connected to the evaporation chamber, and a chamber flap valve is provided between the evaporation chamber and the plasma chamber; Vacuum system; It includes an exhaust system and an air intake system connected to the process chamber, and is used to provide a vacuum environment for the process chamber; An alkali metal evaporation source is disposed in the evaporation chamber and is used to evaporate and deposit the alkali metal onto the substrate; A deflection coil is provided in the plasma chamber and is used to generate a linearly changing magnetic field; A PECVD device is communicated with the plasma chamber and is used to provide plasma to the plasma chamber; The Ar gas inlet system is connected to the PECVD device and is used to provide Ar gas.

2. The alkali metal post-deposition treatment device for CIGS thin-film solar cells according to claim 1, characterized in that: The alkali metal evaporation source is a Na2S evaporation source or a KF evaporation source.

3. The alkali metal post-deposition treatment device for CIGS thin-film solar cells according to claim 1 or 2, characterized in that: A plasma valve is arranged between the PECVD device and the plasma chamber.

4. The alkali metal post-deposition treatment device for CIGS thin-film solar cells according to claim 1 or 2, characterized in that: It also includes a transmission roller, which is arranged at the bottom of the process chamber and is used to transmit the substrate.

5. The alkali metal post-deposition treatment device for CIGS thin-film solar cells according to claim 4, characterized in that: The conveying roller is provided with a substrate loading box for loading the substrate.

6. A method for post-deposition treatment of alkali metals for CIGS thin-film solar cells, characterized in that: Utilizing the device according to any one of claims 1 to 5, comprising the following steps: (1) Turn on the vacuum system and evacuate the process chamber; (2) preheating the substrate with the CIGS absorption layer and transferring it to the evaporation chamber, turning on the alkali metal evaporation source, and evaporating the alkali metal element on the surface of the CIGS absorption layer; (3) Open the Ar gas inlet system and pass Ar into the PECVD device to generate Ar + The plasma is introduced into the plasma chamber, the chamber flap valve is opened, and the substrate with the alkali metal film evaporated is transferred into the plasma chamber. Under the action of the deflection coil, the Ar + The plasma continuously impacts the alkali metal film, increasing the energy of the alkali metal atoms, promoting the alkali metal to aggregate on the front surface of the CIGS absorber layer to form an alloy layer and penetrate into the CIGS grain boundaries.

7. The alkali metal post-deposition treatment method for CIGS thin-film solar cells according to claim 6, characterized in that: In step (2), the substrate with the CIGS absorption layer is preheated to 80-90°C.

8. The alkali metal post-deposition treatment method for CIGS thin-film solar cells according to claim 6, characterized in that: In step (2), the evaporation temperature of the evaporation source is 500-700°C.

9. The alkali metal post-deposition treatment method for CIGS thin-film solar cells according to claim 6 or 8, characterized in that: In step (3), the flow rate of Ar introduced into the PECVD device is 60-120 sccm, and the vacuum degree in the plasma chamber is 1.1×10 -4 ~2.5×10 -4 mbar, and the duration of plasma impact on alkali metal is 5 to 8 minutes.

10. A method for preparing a CIGS thin-film solar cell, characterized in that: The following steps are involved: (1) forming a back electrode on a substrate; (2) depositing a Cu-Na alloy layer, a Cu-Ga alloy layer and an In layer on the back electrode in sequence to form an absorption middle layer; (3) Spraying Se vapor onto the absorbing middle layer to form a Se layer, thereby forming an absorbing prefabricated layer; (4) performing high-temperature selenization on the formed absorption prefabricated layer to form a CIGS absorption layer; (5) Using the alkali metal post-deposition treatment method described in any one of claims 6 to 9, evaporating an alkali metal thin film on the CIGS absorber layer and using Ar + Plasma treatment; (6) evaporating an In2S3 buffer layer and depositing an intrinsic ZnO high-resistance layer; (7) Deposit an AZO film layer on the ZnO high resistance layer.

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