Solar cell and method for producing same

1. A solar cell, comprising:

a substrate;

a first passivation film, an anti-reflection layer and at least one first electrode sequentially formed on a front surface of the substrate; and

a tunneling layer, a field passivation layer and at least one second electrode sequentially formed on a rear surface of the substrate; wherein:

the field passivation layer includes a first field passivation sub-layer corresponding to a portion of the field passivation layer in a first region formed between the at least one second electrode and the substrate, and a second field passivation sub-layer corresponding to a portion of the field passivation layer in a second region formed between adjacent second electrodes;

a conductivity of the first field passivation sub-layer is greater than a conductivity of the second field passivation sub-layer, and a thickness of the second field passivation sub-layer is smaller than a thickness of the first field passivation sub-layer;

wherein either the at least one first electrode or the at least one second electrode serves as a hybrid electrode including a silver electrode, a conductive adhesive and an electrode film sequentially disposed in a direction away from the substrate;

wherein a surface doping concentration of a top surface of the second field passivation sub-layer facing away from the substrate is lower than a surface doping concentration of a top surface of the first field passivation sub-layer facing away from the substrate; and

wherein the first field passivation sub-layer includes an ion diffusion layer and an ion enrichment layer that are sequentially formed in a direction away from the substrate, and a doping concentration of the ion enrichment layer is greater than a doping concentration of the ion diffusion layer; the top surface of the second field passivation sub-layer is lower than the top surface of the first field passivation sub-layer, and a thickness difference between the second field passivation sub-layer and the first field passivation sub-layer is greater than a thickness of the ion enrichment layer in the direction away from the substrate toward the field passivation layer.

2. The solar cell according to claim 1 , wherein a bottom surface of the second field passivation sub-layer is flush with a bottom surface of the first field passivation sub-layer in the direction away from the substrate toward the field passivation layer.

3. The solar cell according to claim 1 , wherein a top surface doping concentration of the first field passivation sub-layer is different from a top surface doping concentration of the second field passivation sub-layer by 0.5E+20/cm 3 ˜1.5E+20/cm 3 .

4. The solar cell according to claim 1 , wherein a thickness of the second field passivation sub-layer is different from a thickness of the first field passivation sub-layer by 50 nm˜80 nm.

5. The solar cell according to claim 1 , wherein the electrode film is made of at least one of a conductive organic compound, a conductive inorganic compound, a non-silver metal and a non-silver metal composite.

6. The solar cell according to claim 5 , wherein the conductive adhesive comprises a base and a conductive particle, wherein the base is made of at least one of an acrylic acid, an epoxy, a silica gel, a maleic anhydride and a hybrid resin, and the conductive particle is made of at least one of a silver, a silver-coated copper, a gold, a nickel and a carbon.

7. A method for producing a solar cell, comprising:

providing a substrate;

sequentially forming a first passivation film, an anti-reflection layer and at least one first electrode on a front surface of the substrate; and

sequentially forming a tunneling layer, a field passivation layer and at least one second electrode on a rear surface of the substrate; wherein

the field passivation layer includes a first field passivation sub-layer corresponding to a portion of the field passivation layer in a first region formed between the at least one second electrode and the substrate and a second field passivation sub-layer corresponding to a portion of the field passivation layer in a second region formed between adjacent second electrodes;

a conductivity of the first field passivation sub-layer is greater than a conductivity of the second field passivation sub-layer, and a thickness of the second field passivation sub-layer is smaller than a thickness of the first field passivation sub-layer;

wherein either the at least one first electrode or the at least one second electrode serves as a hybrid electrode including a silver electrode, a conductive adhesive and an electrode film that are sequentially disposed in a direction away from the substrate;

wherein a surface doping concentration of a top surface of the second field passivation sub-layer facing away from the substrate is lower than a surface doping concentration of a top surface of the first field passivation sub-layer facing away from the substrate; and

wherein the first field passivation sub-layer includes an ion diffusion layer and an ion enrichment layer that are sequentially formed in a direction away from the substrate, and a doping concentration of the ion enrichment layer is greater than a doping concentration of the ion diffusion layer; the top surface of the second field passivation sub-layer is lower than the top surface of the first field passivation sub-layer, and a thickness difference between the second field passivation sub-layer and the first field passivation sub-layer is greater than a thickness of the ion enrichment layer in the direction away from the substrate toward the field passivation layer.

8. The method according to claim 7 , wherein the step of sequentially forming the tunneling layer, the field passivation layer and the at least one second electrode on the rear surface of the substrate sequentially includes:

forming the tunneling layer and a first field passivation film on the rear surface of the substrate;

sequentially forming an ion enrichment layer and an ion diffusion layer in the first field passivation film in a direction away from the substrate via an ion implantation process; wherein:

the ion enrichment layer includes a first enrichment layer in the first region and a second enrichment layer in the second region;

an average doping concentration of the first enrichment layer is identical to an average doping concentration of the second enrichment layer, and a surface doping concentration of a top surface of the first enrichment layer is identical to a surface doping concentration of a top surface of the second enrichment layer in a direction away from the substrate;

forming a mask layer on the first field passivation film in the first region, and etching the second enrichment layer in the second region, wherein the second enrichment layer in the second region is not covered by the mask layer;

removing the mask layer and forming a second passivation film covering a surface of the field passivation layer away from the substrate; and

forming the at least one second electrode.

9. The method according to claim 7 , wherein the step of sequentially forming the tunneling layer, the field passivation layer and the at least one second electrode on the rear surface of the substrate sequentially includes:

forming the tunneling layer and a first field passivation film on the rear surface of the substrate;

sequentially forming an ion enrichment layer and an ion diffusion layer in the first field passivation film in a direction away from the substrate via an ion implantation process; wherein:

the ion enrichment layer includes a first enrichment layer in the first region and a second enrichment layer in the second region;

an average doping concentration of the first enrichment layer is greater than an average doping concentration of the second enrichment layer, and a surface doping concentration of the top surface of the first enrichment layer is greater than a surface doping concentration of the top surface of the second enrichment layer in the direction away from the substrate;

forming a mask layer on the first field passivation film in the first region, and etching the second enrichment layer in the second region, wherein the second enrichment layer in the second region is not covered by the mask layer;

removing the mask layer and forming a second passivation film covering a surface of the field passivation layer away from the substrate; and

forming the at least one second electrode.

10. The method according to claim 8 , wherein the forming the mask layer on the first field passivation film in the first region includes:

forming the mask layer by a screen printing process or an ink jet printing process; wherein the mask layer is made of an organic wax; and a thickness of the organic wax is 50 μm˜300 μm.

11. The method according to claim 8 , wherein the etching the enrichment layer in the second region includes:

controlling the enrichment layer in the second region by a reaction time, a reaction temperature and a solution ratio, wherein the solution ratio is set as HF:HNO3:H2O=1:5:5˜1:25:25, the reaction temperature is 7° C.˜15° C., and the reaction time is 30 s˜90 s;

wherein the removing the mask layer includes: removing the mask layer with an alkaline solution with a concentration of 0.1˜10%.

12. The method according to claim 9 , wherein the forming the at least one second electrode includes:

printing a thin layer of a silver paste on a surface of the second passivation film away from the substrate by a screen printing process;

drying and sintering the silver paste to form the silver electrode penetrating through the second passivation film and contacting the first field passivation sub-layer;

forming the conductive adhesive on the silver electrode;

forming the electrode film on the conductive adhesive;

wherein an adhesive connection between the silver electrode and the electrode film is realized by the conductive adhesive under a preset temperature and pressure condition.

13. The method according to claim 7 , wherein, a thickness of the silver electrode is 1˜5 μm, a thickness of the conductive adhesive is 1˜5 μm, and a thickness of the electrode film is 5˜20 μm.