WO2013159713A1

WO2013159713A1 - Method for preparing silicon dioxide block layer for group i-iii-iv compound solar cell

Info

Publication number: WO2013159713A1
Application number: PCT/CN2013/074695
Authority: WO
Inventors: 任昌义
Original assignee: 深圳市科聚新材料有限公司
Priority date: 2012-04-26
Filing date: 2013-04-25
Publication date: 2013-10-31
Also published as: CN102646756A; CN102646756B

Abstract

A method for preparing a silicon dioxide block layer for a group I-III-IV compound solar cell comprises the following steps: preparing an acid catalysis solution, of ortho-silicic acid alkyl ester, that comprises ortho-silicic acid alkyl ester, ethanol, H₂O, and acid, and adding NH₄OH water solution or adding NH₄OH water solution and ethanol after placement, so as to obtain silica sol; coating the silica sol on a medium, and obtaining a gel membrane after aging; heating and drying the aged gel membrane to obtain a silicon dioxide block layer for a group I-III-IV compound solar cell. The method is simple and is suitable for batch production, and the obtained silicon dioxide block layer can better block heteroatoms on a substrate of the solar cell from spreading.

Description

Method for preparing silicon dioxide barrier layer for I-III-IV compound solar cell

The invention belongs to the field of solar cells, and particularly relates to a method for preparing a silicon dioxide barrier layer for a solar energy battery of a group I-III-IV compound.

Background technique

Typically, I-III-VI compound solar cells are deposited on sodium-containing glass at a temperature of about 550 °C. The efficiency of copper indium gallium selenide (CIGS) solar cells using glass substrates was recorded as 19.9%.

The I-III-VI compound solar cell prepared on the flexible substrate usually uses stainless steel as the substrate, mainly because the stainless steel is resistant to high temperature and can be heated to above 1000 ° C; and its expansion coefficient and expansion of CIGS battery material. The ratio is similar, which ensures better adhesion between the substrate and the battery, and higher efficiency. When using stainless steel as the substrate, a barrier layer must be added to it, one can prevent each series battery from being turned on by the substrate;

The hetero atoms such as Fe and Cr enter the absorption layer by thermal diffusion. The diffusion of heteroatoms such as Fe in a stainless steel substrate has a large influence on the performance of the semiconductor device. A small amount (less than 6.65%) of Fe doping can form Fe _Cu (FeInSe ₂ ), Fe _ln (CuFeSe ₂ ) and other substitution defects in CIGS, and the deep level defect Fe _Cu existing in the battery film will be effective. The composite center increases the in-body recombination of the battery absorption layer, greatly reduces carrier mobility and lifetime, and reduces battery efficiency.

At present, the materials mainly used as the barrier layer are SiO _x and Α1 ₂ 0 ₃ , and the overall performance of SiO _x is superior in terms of cost and barrier efficiency. Since the thickness of the barrier layer is limited (generally 3μιη), there will always be a considerable amount of hetero atoms such as Fe diffusing into the absorption layer, which lowers the battery efficiency. Therefore, the highest efficiency of the CIGS battery based on stainless steel is 17.4% compared to glass. There is still a gap in the efficiency of the substrate's CIGS battery record of 19.9%.

Summary of the invention

The invention provides a method for preparing a silica barrier layer for a group I-III-IV compound solar cell with better barrier effect, which comprises the following steps:

An acid-catalyzed solution of an alkyl orthosilicate containing a molar ratio of 1: (1 to 5): (0.5 to 3): (0.001 to 0.1) of an alkyl orthosilicate, an alcohol, H ₂ 0 and Acid, wherein the molar ratio of the acid is determined by the acid ^ ^:艮;

The acid catalyzed solution of the alkyl orthosilicate is placed for 0.5-6 h, and then a NH ₄ OH solution is added, or an aqueous solution of NH ₄ OH and an alcohol are added to obtain a silica sol, wherein the alkyl orthosilicate, the alcohol, the H ₂ 0 The molar ratio of the acid to the acid is 1: (3 ~ 9): (1 - 6): (0.001 - 0.1), and the molar ratio of NH ₄ OH to acid is 1: 1 ~ 4: 1 ;

Coating the silica sol on the medium in an alcohol atmosphere;

The medium after coating the silica sol is continuously aged in an alcohol atmosphere for 5 to 75 minutes, and then immersed in Aging in an alcohol solution to obtain an aged gel film;

The aged gel film is heated and dried at a heating rate of 10 to 180 ° C / s, and is heated to 150 to 500 ° C for 10 to 75 minutes to obtain a silica barrier layer for the I-III-IV compound solar cell.

The preparation method of the silica barrier layer for the solar cell of the group I-III-IV compound of the invention has simple process equipment and low process temperature, and can effectively control the microstructure of the film. The silicon dioxide barrier layer is compared with the same thickness of the silicon dioxide barrier layer, and the diffusion path is increased due to the presence of the pores, and the cross-sectional area is decreased, thereby increasing the barrier efficiency of the barrier layer, making the absorption layer of the I-III-IV compound solar cell difficult. Under the influence of substrate hetero atom diffusion.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the structure of a silicon dioxide barrier layer for a Group I-III-IV compound solar cell according to an embodiment of the present invention;

Fig. 2 is a scanning electron micrograph of a silicon dioxide barrier layer for a group I-III-IV compound solar cell prepared in Example 1 of the present invention.

detailed description

In order to make the objects, technical solutions, and advantages of the present invention more comprehensible, the present invention will be further described in detail in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The embodiment of the present invention is achieved by providing a method for preparing a silicon dioxide barrier layer for a group I-III-IV compound solar cell, which comprises the following steps:

S01 : preparing an acid-catalyzed solution of an alkyl orthosilicate containing a molar ratio of 1: (1 to 5): (0.5 - 3): (0.001 - 0.1) of an alkyl orthosilicate, an alcohol, H ₂ The molar ratio of 0 to acid and acid is in the range of acid ^:艮, wherein the alcohol is, for example, preferably isopropanol, and the acid is, for example, preferably HCl;

S02: placing the above acid catalyzed solution of the alkyl orthosilicate for 0.5-6 h, then adding a NH ₄ OH solution, or adding an aqueous solution of NH ₄ OH and an alcohol to obtain a silica sol, wherein the alkyl orthosilicate, the alcohol, The molar ratio of 3⁄40 to acid is 1: (3 ~ 9): (1 - 6): (0.001 ~ 0.1), and the molar ratio of NH ₄ OH to acid is 1: 1 ~ 4: 1 ;

S03: coating a silica sol on the medium in an alcohol atmosphere;

S04: the medium after coating the silica sol is further aged in an alcohol atmosphere for 5 to 75 min, and then immersed in an alcohol solution to obtain an aged gel film;

S05: The aged gel film is heated and dried at a heating rate of 10 to 180 ° C / s, and the temperature is raised to 150 to 500 ° C for 10 to 75 minutes to obtain silicon dioxide for the I-III-IV compound solar cell. Barrier layer.

Specifically, in the step S01, the alkyl orthosilicate is preferably methyl orthosilicate and/or tetraethyl orthosilicate. The alcohol has a significant inhibitory effect on the hydrolysis and polycondensation process of the silicon source, and preferably uses isopropanol, which has a low boiling point and a high viscosity, and the effect is better than other alcohols.

In step S02, the molar ratio of NH ₄ OH to acid, such as HC1, is 1:1 to 4:1. Under higher alkaline conditions, the solubility of the silica colloidal particles is increased, and at the same time, the protonated surface charge of the particles is increased, thereby delaying the agglomeration and gelation processes. The high pH gel system can produce high porosity, large pore size and high surface area silica barrier layers. However, Off and H ₂ 0 in the silica sol precursor increase the hardness of the pore walls in the silica barrier layer. Because of its inclusion of Off and H ₂ 0 in the microstructure, during the heat treatment, an alkali-silicon reaction occurs in the silica barrier layer, which causes a change in pore size and porosity in the barrier layer, and even cracking. Preferably, the molar ratio of NH ₄ OH to HCl is from 1.8:1 to 2.2:1.

In step S03, the coating may be carried out by any coating method commonly used in the art, such as immersion pulling, spin coating, screen printing, and blade coating, etc., and the coating thickness is required according to the requirements of the I-III-IV compound solar cell device. Control, such as 3 μιη.

In step S04, after the silica sol is gelled, it needs to undergo aging for a certain period of time to make the hydrogel hard. Gelling and aging can be done at room temperature. In the aging process, the phenomenon of separation of the gel and the moisture layer often occurs, and the phenomenon that the hydrogel produces the detachment phenomenon is usually completed. After the silica sol is converted into a gel, the hydroxyl group-bearing silica molecular group in the hydrogel skeleton interacts (ie, the surface ≡ Si-OH group interaction, condensation dehydration and formation of Si-0-Si bond, increase The strength of the skeleton) is further condensed and brought closer, thereby reducing the space in the grid structure and extruding the water contained therein. The aging in the present invention is aging in an isopropyl alcohol atmosphere, and immersed in an isopropyl alcohol solution for aging for 1 to 3 days, shortening the aging time and improving the aging effect.

Step S05 is specifically: drying the aged gel film under nitrogen or an inert gas atmosphere at a heating rate of 10 to 180 ° C / s, and heating to 150 to 500 ° C for 10 to 75 minutes. During the drying of the hydrogel, the pore structure of the silica gel is formed due to evaporation of water. During the drying process, the skeleton in the hydrogel, due to evaporation of water, creates channels that form capillaries. The water in the capillary (the liquid surface) evaporates and overflows, causing the capillary wall to be subjected to the enormous pressure generated by the evaporation of water and continuously close to shrink the gel skeleton due to the solvated particles of the gel network constituting the capillary wall. The existence of repulsive force tries to maintain the original shape of the skeleton, which leads to the formation of the pore structure of the silica gel. As the dehydration progresses, the gel network skeleton shrinks and the repulsive force between the solvated particles of the gel network increases. Large, when the capillary pressure and the repulsive force are balanced, the gel stops shrinking and the pore structure is fixed. If the skeleton strength of the gel is small and the skeleton deformability is large, it is easy to obtain a fine pore silica gel: If the skeleton strength is large and the skeleton deformability is small, the coarse pore silica gel is easily obtained. If the elasticity and strength of the gel are not sufficient to counteract the capillary pressure, the gel will crack or pulverize during the drying process. When the bulk hydrogel is dried, it is actually the outer gel that loses water first than the inner gel. Due to the limitation of mass transfer rate, the outer layer moisture concentration is lower than the inner layer concentration. The loss of water shrinkage of the outer gel causes the outer gel to be squeezed into the inner gel whose volume has not changed, causing cracks and deformation. Therefore, controlling the appropriate heating rate can avoid cracking and deformation. Preferably, the temperature increase rate is from 20 ° C to 30 ° C / s. The conditions for the heating and drying process are closely related to the aforementioned acid-base environment, water content and aging conditions. Further, preferably, the I-III-IV compound solar cell solar cell is also used. The barrier layer is annealed. The annealing treatment can make the structure of the silicon dioxide barrier layer more dense. The annealing treatment refers to placing the silicon dioxide barrier layer of the I-III-IV compound solar cell into an electric resistance furnace, a tube furnace, a muffle furnace, a rapid heat treatment furnace or other heating furnace at 250 to 800°. Annealing under C for a duration of 10 min ~ 3 h. More preferably, the silicon-blocking layer of the I-III-IV compound solar cell is annealed in a mixed gas atmosphere of nitrogen or an inert gas and hydrogen for a duration of 0.5 min to 1 h, wherein nitrogen or The volume ratio of inert gas to hydrogen is 4:1 to 49:1.

The method for preparing a silicon dioxide barrier layer for a group I-III-IV compound solar cell according to an embodiment of the present invention has a porous structure having a porous structure, and a porous structure is obtained from a schematic diagram of the porous barrier structure (Fig. 1). It can increase the diffusion path of heteroatoms, reduce the diffusion area, increase the barrier effect without increasing the thickness of the barrier layer, reduce the hetero atom concentration, and minimize its influence on energy conversion efficiency. In the preparation method of the silica barrier layer for the I-III-IV compound solar cell, the viscosity of the alkyl orthosilicate, the pH of the system, the drying temperature and the speed all affect the effect of the barrier layer. The use of isopropanol to prepare a silica sol facilitates the formation of a network structure of silica colloid and inhibits the polymerization rate. Moreover, the addition of isopropyl alcohol during the heat treatment prevents the silica barrier layer from being cracked by severe thermal stress. The specific implementation of the present invention will be described in detail below with reference to specific embodiments. Example 1

With a rapid stirring of a magnetic stirrer, a mixture of 3⁄40, HCl and isopropanol was added dropwise to a mixture of tetraethyl orthosilicate (TEOS) and isopropanol to make TEOS: isopropanol: 3⁄40: HC1 The molar ratio is 1:3 : 1 : 1.8X 10 ^-3 ; After standing for 2 h, a mixture of 3⁄40, NH ₄ OH and isopropanol is added dropwise to the above solution to make TEOS: isopropanol: 3⁄40 : The molar ratio of HC1:NH ₄ OH is 1:3: 4: 1.8 x 10- ³ : 3.6 x 10- ³ , and a silica sol is obtained. A silica sol having a certain viscosity was applied to a clean silicon wafer in an isopropyl alcohol atmosphere, and aging was continued for 15 min in an isopropanol atmosphere, followed by immersion in an isopropyl alcohol solution for 1 day. The aged wet gel film is rapidly heated and dried in a rapid heat treatment furnace under a N ₂ atmosphere, and the heating rate is 20 ° C / s during the heating process, and is raised to 300 ° C, and then maintained at this temperature for 30 min. The silica barrier layer for the I-III-IV compound solar cell, as shown in Fig. 2, is a scanning electron micrograph. It can be seen that the barrier layer has a porous structure and is dense and dense. Example 2:

To a mixture of methyl orthosilicate and isopropanol, a mixture of 3⁄40, HCl and isopropanol was added under a rapid stirring of a magnetic stirrer to obtain a molar ratio of TEOS:isopropanol:3⁄40:HC1. 1 : 1 : 0.5 : lx lO"³; After standing for 6 h, a mixture of 3⁄40, NH ₄ OH and isopropanol was added dropwise to the above solution to make TEOS: isopropanol: 3⁄40 : HC1: NH ₄ OH Erbi is 1: 6: 6: 1 x 10- ³ : 3 x 10- ³ , to obtain a silica sol. A silica sol having a certain viscosity was applied to a clean silicon wafer in an isopropyl alcohol atmosphere, and aging was continued for 75 min in an isopropanol atmosphere, followed by immersion in an isopropyl alcohol solution for 3 days. The aged wet gel film is rapidly heated and dried in a rapid heat treatment furnace under a N ₂ atmosphere. The heating rate during the heating process is 10 ° C / s, rises to 500 ° C, and then remains at this temperature for 75 min. This was placed under a high temperature annealing treatment in a mixed atmosphere of nitrogen and hydrogen, wherein an annealing temperature was 800 ° C for 3 h to obtain a silica barrier layer for the I-III-IV compound solar cell. Example 3:

To a mixture of methyl orthosilicate and isopropanol, a mixture of 3⁄40, HCl and isopropanol was added under a rapid stirring of a magnetic stirrer to obtain a molar ratio of TEOS:isopropanol:3⁄40:HC1. 1:5:3: 0.1; After standing for 6 h, a mixture of H ₂ 0, NH ₄ OH and isopropanol was added dropwise to the above solution to make TEOS: isopropanol: 3⁄40 : HC1: NH ₄ OH The molar ratio is 1: 9: 3: 0.1: 0.4, and the silica sol is obtained. A silica sol having a certain viscosity was applied to a clean silicon wafer in an isopropanol atmosphere, and aging was continued for 5 min in an isopropanol atmosphere, followed by immersion in an isopropyl alcohol solution for 1 day. The aged wet gel film is rapidly heated and dried in a rapid heat treatment furnace under a N ₂ atmosphere. The temperature rise rate during the heating process is 10 ° C / s, rises to 150 ° C, and then remains at this temperature for 10 min. This was placed under a high temperature annealing treatment in a mixed atmosphere of nitrogen and hydrogen, wherein an annealing temperature was 250 ° C and a time of 0.5 h to obtain a silica barrier layer for the I-III-IV compound solar cell. Example 4:

With a rapid stirring of a magnetic stirrer, a mixture of 3⁄40, HCl and isopropanol was added dropwise to a mixture of tetraethyl orthosilicate (TEOS) and isopropanol to make TEOS: isopropanol: 3⁄40: HC1 The molar ratio is 1:3: 1: 5xl0"²; After standing for 2 h, a mixture of H ₂ 0, NH ₄ OH and isopropanol is added dropwise to the above solution to make TEOS: isopropanol: 3⁄40 : The molar ratio of HC1:NH ₄ OH is 1: 6 : 2 : 2x l0 - ² : 4x l0 - ² , obtaining a silica sol. A silica sol having a certain viscosity is applied to a clean silicon wafer in an isopropanol atmosphere. Continue to aging in isopropanol atmosphere for 15 min, then immerse in isopropanol solution for 1 day. The aged wet gel film is rapidly heated and dried in a rapid heat treatment furnace under N ₂ atmosphere, and the heating rate is increased during heating. The temperature is 20 ° C / s, raised to 300 ° C, and then maintained at this temperature for 30 min, to obtain a silica barrier layer for I-III-IV compound solar cells. The above is only a preferred embodiment of the present invention. For example, the above-described embodiments may be modified in accordance with the teachings of the present invention.

Claims

Rights request

A method for preparing a silicon dioxide barrier layer for a group I-III-IV compound solar cell, comprising the steps of:

An acid-catalyzed solution of an alkyl orthosilicate containing a molar ratio of 1: (1 to 5): (0.5 - 3): (0.001 to 0.1) of an alkyl orthosilicate, an alcohol, H ₂ 0 and Acid, the molar ratio of the acid is based on acid hydrazine, the same below;

The solution of the acid-catalyzed n-alkyl silicate placed 0.5 ~ 6 h, followed by addition of aqueous NH ₄ OH or NH ₄ OH was added and aqueous alcohol, to obtain a silica sol, wherein the n-alkyl silicate, alcohol, H ₂₀ and a molar ratio of acid is 1: (3 ~ 9): (1 - 6): (0.001 - 0.1), NH 4 OH and the molar ratio of the acid is 1: 1 to 4: 1;

Coating the silica sol on a medium in an alcohol atmosphere;

The medium after coating the silica sol is further aged in an alcohol atmosphere for 5 to 75 min, and then immersed in an alcohol solution to obtain an aged gel film;

The aged gel film is heated and dried at a heating rate of 10 to 180 ° C / s, and is heated to 150 to 500 ° C for 10 to 75 minutes to obtain a silicon dioxide for the I-III-IV compound solar cell. Barrier layer.

The method according to claim 1, wherein the alcohol is selected from isopropanol, and/or the acid is selected from HC1.

The method according to claim 2, wherein the alkyl orthosilicate is methyl orthosilicate and/or ethyl orthosilicate.

The method according to claim 2, wherein the molar ratio of NH ₄ OH to HCl is 1.8:1 to 2.2:1.

The preparation method according to claim 2, wherein the immersion in the isopropyl alcohol solution is aging for 1 to 3 days.

The method according to claim 2, wherein the aged gel film is subjected to elevated temperature drying under a nitrogen gas or an inert gas atmosphere.

7. The method according to claim 2, further comprising the step of annealing the silicon dioxide barrier layer for the Group I-III-IV compound solar cell.

The preparation method according to claim 7, wherein the annealing treatment has a heating temperature of 250 to 800 ° C and a time of 10 min to 3 h.

The preparation method according to claim 7, wherein the annealing treatment is performed under a mixed gas atmosphere of nitrogen or an inert gas and hydrogen for a duration of 0.5 min to 1 h, nitrogen or an inert gas and hydrogen. The volume ratio is 4: 1 ~ 49: 1.

The preparation method according to claim 2, wherein the coating is performed by at least one of dipping, spin coating, screen printing, and blade coating.

The method according to claim 2, wherein the temperature increase rate is from 20 ° C to 30 ° C / s at elevated temperature and drying.