CN106299036A - A kind of SnZnO cushion for solaode - Google Patents

Abstract

The invention discloses a SnZnO buffer layer for solar cells. The preparation steps are as follows: step 1, adding zinc acetate to absolute ethanol, stirring evenly, adding acetic acid dropwise, stirring evenly to form a zinc acetate solution; step 2 , adding diethanolamine to the zinc acetate solution, and adding organic tin salt at the same time, stirring to form a zinc-tin mixed solution; step 3, putting the zinc-tin mixed solution into the reaction kettle, adding EDTA, stirring evenly, and performing an aeration reaction for 3-5h; Step 4, distilling the mixed solution after the aeration reaction for 2-4 hours to obtain a mixed concentrated solution; Step 5, adding the mixed concentrated solution to a dispersant for low-temperature stirring, and standing and aging for 3-8 hours; Step 6, mixing the mixed solution The concentrated solution is coated on the base material and sintered at high temperature for 2-4 hours; step 7, the sintered base material is placed in an ethylenediamine gas atmosphere for high-temperature and high-pressure reaction, and the buffer layer can be obtained after cooling. The invention effectively improves the compactness of the buffer layer, repairs the defect problem of the buffer layer film, effectively reduces carrier recombination, thereby significantly improving the short-circuit current density and filling factor of the battery, and realizing the energy conversion efficiency of the battery.

Description

A kind of SnZnO buffer layer for solar cells

technical field

The invention belongs to the technical field of solar energy, and in particular relates to a SnZnO buffer layer used in solar cells.

Background technique

Copper Indium Gallium Selenide (CIGS) thin-film solar cells have the characteristics of low cost, high conversion efficiency and good stability, and are one of the hot research topics in the field of solar cells. In 2013, the Swiss Federal Laboratory for Materials Science and Technology (EmPa) announced that its flexible substrate CIGS solar photovoltaic cell had set a new world record with a high conversion efficiency of 20.4%. The traditional structure of CIGS thin-film solar cells is Basis/Mo/CIGS/CdS/ZnO/AZO, in which CdS is the buffer layer, and the use of CdS as the buffer layer has the following disadvantages: first, CdS is a toxic chemical substance; second, the preparation of CdS buffer layer The commonly used method is the chemical bath method (CBD), while the other layers of thin-film solar cells are usually prepared by dry method in vacuum. Therefore, if a production line of dry and wet mixing processes is used, the complexity of the process will be increased. In addition, since the bandgap of CdS thin films is between 2.3 and 2.4 eV, only the spectral range below the blue light wavelength in the solar spectrum can be absorbed by the cells, which limits the further improvement of the efficiency of thin-film solar cells.

It is in this situation that people have been working hard to find materials that can replace CdS as a buffer layer in the past ten or twenty years, and some results have been achieved so far. It mainly includes replacing CdS with thin film materials such as ZnS, ZnSe, ZnO, In ₂ Se ₃ , _InZnSex as the buffer layer. Among them, ZnO is a multifunctional n-type II-VI compound semiconductor material. Its average light transmittance in the visible light range can reach more than 85%, and the exciton binding energy can reach 60meV. Therefore, ZnO has become an alternative to CdS as a buffer layer. One of the ideal materials. In 2000 and 2003, Delahoy and Platzer-bjorkman proposed to replace CdS film directly with ZnO film as the buffer layer material, and the experimental results showed that using ZnO instead of CdS as the buffer layer material can achieve relatively ideal photoelectric performance, and ZnO/ The short-circuit current of the CIGS heterojunction is even better than that of the CdS/CIGS heterojunction.

The existing methods for preparing ZnO buffer layer include sol-gel method and microwave hydrothermal method, but there are technical problems such as poor crystallinity of the prepared film, voids, and difficulty in controlling the thickness of the film.

Contents of the invention

The purpose of the present invention is to provide a SnZnO buffer layer for solar cells. The present invention effectively improves the compactness of the buffer layer, repairs the defect problem of the buffer layer film, effectively reduces carrier recombination, thereby significantly improving the battery short-circuit current density and Fill factor to achieve battery energy conversion efficiency.

A kind of SnZnO buffer layer for solar cells, its preparation steps are as follows:

Step 1, adding zinc acetate to absolute ethanol, after stirring evenly, adding acetic acid dropwise, stirring evenly to form a zinc acetate solution;

Step 2, adding diethanolamine to zinc acetate solution, adding organic tin salt at the same time, stirring to form zinc-tin mixed solution;

Step 3, put the zinc-tin mixture into the reaction kettle, add EDTA, stir evenly, and carry out aeration reaction for 3-5 hours;

Step 4, distilling the mixed solution after the aeration reaction for 2-4 hours to obtain a mixed concentrated solution;

Step 5, adding the mixed concentrate to the dispersant, stirring at low temperature, and standing for 3-8 hours;

Step 6, coating the mixed concentrated solution on the substrate, and performing high-temperature sintering for 2-4 hours;

In step 7, the sintered substrate is placed in an ethylenediamine gas atmosphere for high-temperature and high-pressure reaction, and the buffer layer can be obtained after cooling.

The formula of described buffer layer is as follows:

15-20 parts of zinc acetate, 30-50 parts of absolute ethanol, 0.3-0.7 parts of acetic acid, 2-4 parts of diethanolamine, 15-20 parts of organic tin salt, 20-40 parts of EDTA, 3-7 parts of dispersant.

The organotin salt is one of dimethyltin, dioctyltin or tetraphenyltin.

The dispersant is one of polyvinylpyrrolidone, benzyltriethylammonium chloride or benzyltrimethylammonium chloride.

The stirring speed in the step 1 and step 2 is 500-1200r/min.

The aeration reaction gas in the step 3 is ammonia, the flow rate of the aeration gas is 30-50mL/min, and the aeration reaction temperature is 60-80°C.

The distillation reaction in step 4 adopts a water-bath distillation method, the temperature of the distillation reaction is 80-95° C., and the volume after the distillation is 40-70% of the mixed solution.

The stirring temperature in the step 5 is 20-30°C, the stirring speed is 1000-1500r/min, and the aging temperature is 5-10°C.

The coating area in step 6 is 1-1.5mL/cm ² , the sintering temperature is 200-350°C, and the sintering reaction pressure is 0.2-0.8MPa.

The amount of ethylenediamine in the step 7 is 7-10 times that of zinc acetate, the temperature of the high temperature and high pressure reaction is 150-180°C, the pressure is 1.1-2.3MPa, and the time of the high temperature and high pressure reaction is 2-2. 4h, the temperature of the cooling reaction is natural cooling.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention effectively improves the compactness of the buffer layer, repairs the defects of the buffer layer film, effectively reduces carrier recombination, thereby significantly improving the short-circuit current density and fill factor of the battery, and realizing the energy conversion efficiency of the battery.

2. The present invention improves the smoothness of the surface of the buffer layer, reduces the flocs on the surface of the buffer layer, reduces the recombination of frontal carriers at the buffer layer/window layer interface, and improves the short-circuit current density of thin-film solar cells by 1.0-2.0mA/cm ^2. Improve the absolute value of battery conversion efficiency by 1-3%.

3. Both the aeration gas and the distilled liquid used in the present invention can be reused, the process cost is low, and the requirements of environmental protection are met. At the same time, the equipment is simple and reliable, the operation is safe, and it is suitable for industrial production.

detailed description

The present invention will be further described below in conjunction with embodiment:

Example 1

A kind of SnZnO buffer layer for solar cells, its preparation steps are as follows:

Step 1, adding zinc acetate to absolute ethanol, after stirring evenly, adding acetic acid dropwise, stirring evenly to form a zinc acetate solution;

Step 2, adding diethanolamine to zinc acetate solution, adding organic tin salt at the same time, stirring to form zinc-tin mixed solution;

Step 3, put the zinc-tin mixture into the reaction kettle, add EDTA, stir evenly, and carry out aeration reaction for 3-5 hours;

Step 4, distilling the mixed solution after the aeration reaction for 2 hours to obtain a mixed concentrated solution;

Step 5, adding the mixed concentrate to the dispersant, stirring at low temperature, and standing for 3 hours;

Step 6, coating the mixed concentrated solution on the substrate, and performing high-temperature sintering for 2 hours;

In step 7, the sintered substrate is placed in an ethylenediamine gas atmosphere for high-temperature and high-pressure reaction, and the buffer layer can be obtained after cooling.

The formula of described buffer layer is as follows:

15 parts of zinc acetate, 30 parts of absolute ethanol, 0.3 parts of acetic acid, 2 parts of diethanolamine, 15 parts of organic tin salt, 20 parts of EDTA, and 3 parts of dispersant.

The organic tin salt adopts dimethyl tin.

The dispersant adopts polyvinylpyrrolidone.

The stirring speed in said step 1 and step 2 is 500r/min.

The aeration reaction gas in the step 3 is ammonia, the flow rate of the aeration gas is 30mL/min, and the aeration reaction temperature is 60°C.

The distillation reaction in step 4 adopts a water-bath distillation method, the temperature of the distillation reaction is 80° C., and the volume after the distillation is 40% of the mixed solution.

The stirring temperature in the step 5 is 20°C, the stirring speed is 1000r/min, and the aging temperature is 5°C.

The coating area in step 6 is 1 mL/cm ² , the sintering temperature is 200° C., and the pressure of the sintering reaction is 0.2 MPa.

The amount of ethylenediamine in the step 7 is 7 times that of zinc acetate, the temperature of the high temperature and high pressure reaction is 150°C, the pressure is 1.1MPa, the time of the high temperature and high pressure reaction is 2h, and the temperature of the cooling reaction for natural cooling.

Example 2

A kind of SnZnO buffer layer for solar cells, its preparation steps are as follows:

Step 1, adding zinc acetate to absolute ethanol, after stirring evenly, adding acetic acid dropwise, stirring evenly to form a zinc acetate solution;

Step 2, adding diethanolamine to zinc acetate solution, adding organic tin salt at the same time, stirring to form zinc-tin mixed solution;

Step 3, put the zinc-tin mixture into the reactor, add EDTA, stir evenly, and carry out aeration reaction for 5 hours;

Step 4, distilling the mixed solution after the aeration reaction for 4 hours to obtain a mixed concentrated solution;

Step 5, adding the mixed concentrate to the dispersant, stirring at low temperature, and standing for 8 hours;

Step 6, coating the mixed concentrated solution on the substrate, and performing high-temperature sintering for 4 hours;

In step 7, the sintered substrate is placed in an ethylenediamine gas atmosphere for high-temperature and high-pressure reaction, and the buffer layer can be obtained after cooling.

The formula of described buffer layer is as follows:

20 parts of zinc acetate, 50 parts of absolute ethanol, 0.7 parts of acetic acid, 4 parts of diethanolamine, 20 parts of organic tin salt, 40 parts of EDTA, and 7 parts of dispersant.

The organotin salt adopts dioctyltin.

The dispersant adopts benzyltriethylammonium chloride.

The stirring speed in the step 1 and step 2 is 1200r/min.

The aeration reaction gas in the step 3 is ammonia, the flow rate of the aeration gas is 50mL/min, and the aeration reaction temperature is 80°C.

The distillation reaction in step 4 adopts a water-bath distillation method, the temperature of the distillation reaction is 95° C., and the volume after the distillation is 70% of the mixed solution.

The stirring temperature in the step 5 is 30°C, the stirring speed is 1500r/min, and the aging temperature is 10°C.

The coating area in step 6 is 1.5 mL/cm ² , the sintering temperature is 350° C., and the pressure of the sintering reaction is 0.8 MPa.

The amount of ethylenediamine in the step 7 is 10 times that of zinc acetate, the temperature of the high temperature and high pressure reaction is 180°C, the pressure is 2.3MPa, the time of the high temperature and high pressure reaction is 4h, and the temperature of the cooling reaction for natural cooling.

Example 3

A kind of SnZnO buffer layer for solar cells, its preparation steps are as follows:

Step 1, adding zinc acetate to absolute ethanol, after stirring evenly, adding acetic acid dropwise, stirring evenly to form a zinc acetate solution;

Step 2, adding diethanolamine to zinc acetate solution, adding organic tin salt at the same time, stirring to form zinc-tin mixed solution;

Step 3, put the zinc-tin mixture into the reaction kettle, add EDTA, stir evenly, and carry out aeration reaction for 4 hours;

Step 4, distilling the mixed solution after the aeration reaction for 3 hours to obtain a mixed concentrated solution;

Step 5, adding the mixed concentrate to the dispersant, stirring at low temperature, and standing for 5 hours;

Step 6, coating the mixed concentrated solution on the substrate, and performing high-temperature sintering for 3 hours;

In step 7, the sintered substrate is placed in an ethylenediamine gas atmosphere for high-temperature and high-pressure reaction, and the buffer layer can be obtained after cooling.

The formula of described buffer layer is as follows:

18 parts of zinc acetate, 40 parts of absolute ethanol, 0.4 parts of acetic acid, 3 parts of diethanolamine, 18 parts of organic tin salt, 35 parts of EDTA, and 5 parts of dispersant.

The organotin salt adopts tetraphenyltin.

The dispersant adopts benzyltrimethylammonium chloride.

The stirring speed in said step 1 and step 2 is 800r/min.

The aeration reaction gas in the step 3 is ammonia, the flow rate of the aeration gas is 40mL/min, and the aeration reaction temperature is 70°C.

The distillation reaction in step 4 adopts a water-bath distillation method, the temperature of the distillation reaction is 90° C., and the volume after the distillation is 60% of the mixed solution.

The stirring temperature in the step 5 is 25°C, the stirring speed is 1300r/min, and the aging temperature is 8°C.

The coating area in step 6 is 1.3 mL/cm ² , the sintering temperature is 250° C., and the sintering reaction pressure is 0.5 MPa.

The amount of ethylenediamine in the step 7 is 9 times that of zinc acetate, the temperature of the high temperature and high pressure reaction is 170°C, the pressure is 1.8MPa, the time of the high temperature and high pressure reaction is 3h, and the temperature of the cooling reaction for natural cooling.

The performance detection effect of embodiment 1-3 is as follows:

project Example 1 Example 2 Example 3 membrane thickness 120nm 123nm 106nm Visible light transmittance 86.9% 88.7% 90.2% Bandgap width 3.24eV 3.31eV 3.09eV

The above description is only an embodiment of the present invention, and does not limit the present invention. All technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (10)

1. a SnZnO buffer layer for solar cells, characterized in that its preparation steps are as follows: Step 1, adding zinc acetate to absolute ethanol, after stirring evenly, adding acetic acid dropwise, stirring evenly to form a zinc acetate solution; Step 2, adding diethanolamine to zinc acetate solution, adding organic tin salt at the same time, stirring to form zinc-tin mixed solution; Step 3, put the zinc-tin mixture into the reaction kettle, add EDTA, stir evenly, and carry out aeration reaction for 3-5 hours; Step 4, distilling the mixed solution after the aeration reaction for 2-4 hours to obtain a mixed concentrated solution; Step 5, adding the mixed concentrate to the dispersant, stirring at low temperature, and standing for 3-8 hours; Step 6, coating the mixed concentrated solution on the substrate, and performing high-temperature sintering for 2-4 hours; In step 7, the sintered substrate is placed in an ethylenediamine gas atmosphere for high-temperature and high-pressure reaction, and the buffer layer can be obtained after cooling. 2. a kind of SnZnO buffer layer for solar cell according to claim 1, is characterized in that, the formula of described buffer layer is as follows: 15-20 parts of zinc acetate, 30-50 parts of absolute ethanol, 0.3-0.7 parts of acetic acid, 2-4 parts of diethanolamine, 15-20 parts of organic tin salt, 20-40 parts of EDTA, 3-7 parts of dispersant. 3 . A SnZnO buffer layer for solar cells according to claim 2 , wherein the organotin salt is one of dimethyltin, dioctyltin or tetraphenyltin. 4 . 4. A kind of SnZnO buffer layer for solar cell according to claim 2, is characterized in that, described dispersion agent adopts polyvinylpyrrolidone, benzyltriethylammonium chloride or benzyltrimethylammonium chloride One of. 5. A SnZnO buffer layer for solar cells according to claim 1, characterized in that, the stirring speed in the step 1 and step 2 is 500-1200r/min. 6. A kind of SnZnO buffer layer for solar cells according to claim 1, characterized in that, the aeration reaction gas in the step 3 is ammonia, and the flow rate of the aeration gas is 30-50mL/ min, the aeration reaction temperature is 60-80°C. 7. A kind of SnZnO buffer layer for solar cells according to claim 1, characterized in that, the distillation reaction in the step 4 adopts a water-bath distillation method, and the temperature of the distillation reaction is 80-95 ° C, the The volume after the distillation is 40-70% of the mixed liquor. 8. A SnZnO buffer layer for solar cells according to claim 1, characterized in that, the stirring temperature in the step 5 is 20-30°C, the stirring speed is 1000-1500r/min, the The aging temperature is 5-10°C. 9. A SnZnO buffer layer for solar cells according to claim 1, characterized in that, the coating area in the step 6 is 1-1.5mL/cm ² , and the sintering temperature is 200-350 °C, the pressure of the sintering reaction is 0.2-0.8 MPa. 10. a kind of SnZnO buffer layer that is used for solar cell according to claim 1, is characterized in that, the amount of ethylenediamine in the described step 7 is 7-10 times of zinc acetate, and the high temperature and high pressure reaction The temperature is 150-180° C., the pressure is 1.1-2.3 MPa, the time for the high temperature and high pressure reaction is 2-4 hours, and the temperature for the cooling reaction is natural cooling.