A kind of preparation method of two-sided heterojunction solar cell
Technical field
The present invention relates to technical field of solar cells, especially a kind of two-sided heterojunction solar cell and preparation method.
Background technology
Silicon heterojunction solar battery be in crystalline silicon substrate deposition of amorphous silicon films as emitter, but doped amorphous silicon emitter film can absorption portion visible ray, thus have impact on the effective utilization of base substrate to light, be unfavorable for the short wave response of battery, limit the conversion efficiency of solar cell, visible, the optical absorption reducing emission layer becomes the effective way improving heterojunction solar cell conversion efficiency.At present, the main broad-band gap silicon thin film that adopts is as emission layer, but the doping process cost of complexity is higher, and broad-band gap doping film electric property can not ensure.
Adopt heterojunction solar cell prepared by traditional screen printing technique, front electrode area coverage accounts for about 10% of whole cell area, have a strong impact on the abundant absorption of battery to light, but, current electrode fabrication is difficult to the depth-width ratio structure of realizing ideal, and with regard to silk screen printing, requires higher to equipment, slurry etc., for this reason, the preparation of front electrode becomes the key technology improving heterojunction solar cell conversion efficiency.
Another principal element affecting heterojunction solar cell is interfacial state compound, the emission layer of traditional silicon heterojunction solar cell covers the whole area of monocrystalline substrate, the contact interface in interface is comparatively large, but film/crystal silicon interracial contact problem is the bottleneck of hetero-junction solar cell conversion efficiency always.Little interface area effectively reduces Interface composites, is conducive to the raising of open circuit voltage.
Summary of the invention
The technical problem to be solved in the present invention is: overcome the deficiency in prior art, a kind of two-sided heterojunction solar cell and preparation method are provided, to reduce traditional silicon heterojunction solar cell emitter to the absorption of light, effective spectral response improving battery, reduce the recombination losses of interface, improve the open circuit voltage of battery, process simplification, reduce process costs.
The technical solution adopted for the present invention to solve the technical problems is: a kind of two-sided heterojunction solar cell, comprise silicon chip base layer, the described silicon chip base layer back side has intrinsic layer from inside to outside successively, heavy doping BSF layer and back electrode, the front of silicon chip base layer has the cell body be arranged in parallel in skewed side, cell body inclined-plane is respectively equipped with intrinsic silicon film and p-type silicon membrane layer, p-type silicon membrane layer is provided with the transparent conductive film as front electrode, transparent conductive film and cell body bottom surface are respectively equipped with film anti-reflection layer, silicon chip base layer surface also has the silver slurry layer be electrically connected with transparent conductive film.
Further, the side wall slope of described cell body is 45 °, and cell body bottom width is 10 μm, and the cell body degree of depth is 80 μm.
The thickness of described silicon chip base layer is 150 ~ 300 μm, and the thickness of heavy doping BSF layer is 10 ~ 50nm, and the thickness of back electrode is 1 ~ 3 μm, and the thickness of intrinsic silicon film is 5 ~ 10nm, and the thickness of p-type silicon membrane layer is 5 ~ 30nm.
Described back electrode material is aluminium film.
A preparation method for above-mentioned two-sided heterojunction solar cell, has following steps:
1) adopt thickness be the N-shaped monocrystalline silicon piece of 150 ~ 300 μm as the silicon chip base layer of substrate, and routine carried out to silicon chip base layer surface clean;
2) adopt PECVD deposition intrinsic layer at the silicon chip base layer back side, at intrinsic layer surface deposition one deck heavy doping BSF layer, thickness is 10 ~ 50nm, forms the back surface field BSF that can improve carrier transport simultaneously;
3) magnetron sputtering mode deposit thickness is adopted to be that 1 ~ 3 μm of aluminium film is as back electrode on heavy doping BSF layer surface;
4) laser grooving mode is adopted to prepare the cell body of parallel skewed side in silicon chip base layer front;
5) carry out conventional chemical cleaning in cell body, and in cell body, adopt PECVD or HWCVD or LPCVD method deposition intrinsic silicon thin film and p-type silicon membrane layer successively;
6) utilize wet etching method to carry out etching to the p-type silicon membrane layer bottom cell body to remove, retain the p-type silicon membrane layer on cell body inclined-plane;
7) on p-type silicon membrane layer, adopt magnetron sputtering deposition transparent conductive film, on transparent conductive film, then adopt screen printing technique to prepare low-temperature silver pulp layer, and dry formation electrode under lower than 200 DEG C of conditions;
8) adopt in other regions, silicon chip base layer front PECVD method in conjunction with mask technique deposit film anti-reflection layer, obtain heterojunction solar cell.
The invention has the beneficial effects as follows: the present invention, by arranging skewed cell body in silicon chip base layer front, utilizes cell body inclined plane planimetric area less, can reduce front electrode and lose the shading of whole battery, effectively improve the spectral response of battery; Simultaneously because p-type silicon membrane layer is only positioned on cell body inclined-plane, contact area reduces, and reduces the recombination losses of interface, improves the open circuit voltage of battery; The metal electrode photosensitive area tilted reduces, and decreases the absorption of emitter region to light, improves the short wave response of whole battery.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the present invention is further described.
Fig. 1 is the structural representation of two-sided heterojunction solar cell of the present invention.
Fig. 2 is the preparation flow figure of two-sided heterojunction solar cell of the present invention.
1. silicon chip base layer 2. intrinsic layer 3. heavy doping BSF layer 4. back electrode 5. cell body 6. intrinsic silicon film 7.p type silicon membrane layer 8. film anti-reflection layer 9. silver slurry layer 10. transparent conductive films in figure
Embodiment
The present invention is further illustrated with preferred embodiment by reference to the accompanying drawings now.These accompanying drawings are the schematic diagram of simplification, only basic structure of the present invention are described in a schematic way, and therefore it only shows the formation relevant with the present invention.
The two-sided heterojunction solar cell of one as shown in Figure 1, comprise the silicon chip base layer 1 selecting N-shaped monocrystalline silicon piece to make, the thickness of silicon chip base layer 1 is 200 μm, resistivity is 5 Ω, and described silicon chip base layer 1 back side has intrinsic layer 2, heavy doping BSF layer 3 and back electrode 4 from inside to outside successively, wherein, the thickness of intrinsic layer 2 is 5nm, the thickness of heavy doping BSF layer 3 is 20nm, and back electrode 4 is selected aluminium film to deposit and formed, and thickness is 1.5 μm.
The front of silicon chip base layer 1 has the cell body 5 be arranged in parallel in skewed, the inclined side of cell body 5 adopts laser grooving technology to obtain, cross section is trapezoidal shape, the side wall slope of cell body 5 is 45 °, cell body 5 bottom width is 10 μm, cell body 5 degree of depth is 80 μm, cell body inclined-plane is respectively equipped with intrinsic silicon film 6 and p-type silicon membrane layer 7, p-type silicon membrane layer 7 is provided with the transparent conductive film 10 as front electrode, the thickness of p-type silicon membrane layer 7 is 10nm, this structure, make to become inclination contact between p-type silicon membrane layer 7 with the transparent conductive film 10 as front electrode, contact area is between the two reduced, reduce the recombination losses of interface, improve the open circuit voltage of battery.Other surfaces of transparent conductive film 10 and cell body 5 bottom surface are respectively equipped with film anti-reflection layer 8, and silicon chip base layer 1 surface also has the silver slurry layer 9 be electrically connected with transparent conductive film 10.
The above-mentioned n-type silicon chip as silicon chip base layer 1 can be monocrystalline silicon piece, also can be polysilicon chip, on cell body 5 inclined-plane before depositing p-type silicon membrane layer 7, also first can deposit the thick intrinsic a-Si:H layer of one deck 5nm as buffer transition layer.
A preparation method for above-mentioned two-sided heterojunction solar cell, see accompanying drawing 2, has following steps:
1) adopt the silicon chip base layer 1 of N-shaped monocrystalline silicon piece as substrate that thickness is 200 μm, resistivity is 5 Ω, and routine cleaning is carried out to silicon chip base layer 1 surface;
2) adopt at silicon chip base layer 1 back side PECVD to deposit the thick intrinsic layer of one deck 5nm 2, at the heavily doped silicon thin film of intrinsic layer 2 surface deposition one deck, form the heavy doping BSF layer 3 that thickness is 20nm;
3) magnetron sputtering mode deposit thickness is adopted to be that 1.5 μm of aluminium films are as back electrode 4 on heavy doping BSF layer 3 surface;
4) adopt laser grooving mode to prepare parallel skewed cell body 5 in silicon chip base layer 1 front, the side wall slope of cell body 5 is 45 °, and cell body 5 bottom width is 10 μm, and cell body 5 degree of depth is 80 μm, carries out conventional chemical cleaning in cell body 5;
5) in cell body 5, adopt PECVD method first to deposit the thick intrinsic silicon film 6 of one deck 5nm, then deposit the thick p-type silicon membrane layer 7 of 10nm, and on 7, deposit the transparent conductive film 10 of 100nm;
6) utilize wet etching method to carry out etching to the p-type silicon membrane layer 7 bottom cell body 5 to remove, retain intrinsic silicon film 6, p-type silicon membrane layer 7 and the transparent conductive film 10 on cell body 5 inclined-plane;
7) at the silver slurry layer 9 of the surface screen-printed low temperature of transparent conductive film 10, and low temperature drying forms metal electrode under lower than 200 DEG C of conditions;
8) in other regions, silicon chip base layer 1 front, namely the surface of transparent conductive film 10 and cell body 5 bottom surface adopt PECVD method to deposit, form film anti-reflection layer 8, finally obtain heterojunction solar cell.
The present invention is obliquely installed because transparent conductive film 10 adopts, p-type silicon membrane layer 7 is arranged on again on cell body 5 inclined plane, make to become inclination contact between p-type silicon membrane layer 7 with transparent conductive film 10, take full advantage of the factor that cell body 5 inclined plane planimetric area is less, thus reduction front electrode loses the shading of whole battery, effectively improve the spectral response of battery, reduce emitter region to the absorption of light, improve the short wave response of battery, simultaneously, reduce interfacial state compound, be conducive to the raising of cell integrated performance.
Above-described embodiment is only for illustrating technical conceive of the present invention and feature; its object is to person skilled in the art can be understood content of the present invention and be implemented; can not limit the scope of the invention with this; all equivalences done according to Spirit Essence of the present invention change or modify, and all should be encompassed in protection scope of the present invention.