Passivated contact solar cell and photovoltaic module
By setting a work function between the first doped polysilicon layer and the first electrode of the passivation contact solar cell, the metal recombination problem caused by direct contact between the metal electrode and the silicon substrate is solved, and the conversion efficiency of the solar cell is improved.
Patent Information
- Application Number
- CN202420366219.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-27
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2034-02-27
AI Technical Summary
The existing passivation contact solar cells have increased metal recombination due to the direct contact metal electrodes and silicon substrates, which limits the conversion efficiency of the solar cells.
A second dielectric layer is arranged between the first doped polysilicon layer and the first electrode, and the work function of the second dielectric layer is greater than the work function of the first doped polysilicon layer, reducing the possibility of metal contact recombination.
The conversion efficiency of passivation contact solar cells is improved, and metal composite, photoparasitic absorption and Auger composite phenomena are reduced.
Smart Images
Figure CN222692232U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of solar cells, in particular to a passivated contact solar cell and a photovoltaic component. Background Art
[0002] In the related art, the passivated contact solar cell directly performs heavy doping of elements on the surface of the silicon substrate to form a heavily doped layer to serve as the emitter, and then makes ohmic contact with the heavily doped layer through a metal electrode.
[0003] The metal electrode is in contact with the heavily doped layer directly formed on the surface of the silicon substrate, that is, the metal electrode is in direct contact with the silicon substrate. The passivation contact solar cell with this structure has a large metal composite, which limits the conversion efficiency of the solar cell. Utility Model Content
[0004] In order to solve the above technical problems, the present application discloses a passivated contact solar cell and a photovoltaic module. The passivated contact solar cell sets a second dielectric layer between the first doped polysilicon layer and the first electrode. The work function of the second dielectric layer is greater than the work function of the first doped polysilicon layer, thereby reducing the possibility of metal contact recombination at the interface between the first doped polysilicon layer and the first electrode, thereby improving the conversion efficiency of the passivated contact solar cell.
[0005] In a first aspect, an embodiment of the present application provides a passivated contact solar cell, comprising a silicon substrate, a first dielectric layer, a first doped polysilicon layer, a second dielectric layer and a first electrode;
[0006] The first doped polysilicon layer has a first conductivity type, and the silicon substrate has the first conductivity type or a second conductivity type opposite to the first conductivity type;
[0007] The silicon substrate has a light-receiving surface, the light-receiving surface has a local first region, the region of the light-receiving surface outside the first region is a second region, and the doping concentration of the second region is 9×10 13 Pieces / cm 3 ~3×10 16 Pieces / cm 3 ;
[0008] The first dielectric layer, the first doped polysilicon layer, the second dielectric layer and the first electrode are sequentially stacked on the first region in a direction away from the silicon substrate, and a work function of the second dielectric layer is greater than a work function of the first doped polysilicon layer.
[0009] Optionally, a work function of the second dielectric layer and a work function of the first doped polysilicon layer have a difference of 0.1 eV to 2 eV.
[0010] Optionally, the work function of the second dielectric layer is 4.5 eV to 6.8 eV;
[0011] And / or, the work function of the first doped polysilicon layer is 4.0 eV to 5.5 eV.
[0012] Optionally, the second dielectric layer is a transition metal oxide layer.
[0013] Optionally, the material of the transition metal oxide layer is selected from any one of molybdenum oxide, vanadium oxide, tungsten oxide or copper oxide.
[0014] Optionally, the first dielectric layer, the first doped polysilicon layer, the second dielectric layer and the first electrode have the same width;
[0015] And / or, the cross-sectional areas of the first doped polysilicon layer, the second dielectric layer and the first electrode are equal.
[0016] Optionally, the passivation contact solar cell further comprises a third dielectric layer, a second doped polysilicon layer and a second electrode; the second doped polysilicon layer has the second conductivity type;
[0017] The silicon substrate further comprises a backlight surface which is arranged opposite to the light receiving surface, and the third dielectric layer, the second doped polysilicon layer and the second electrode are sequentially stacked on the backlight surface in a direction away from the silicon substrate.
[0018] Optionally, the passivated contact solar cell further comprises a functional layer arranged on the second region.
[0019] Optionally, the silicon substrate is an N-type silicon substrate, the first doped polysilicon layer is a P-type doped polysilicon layer, the first electrode is an aluminum electrode, the second doped polysilicon layer is an N-type doped polysilicon layer, and the second electrode is a silver electrode;
[0020] And / or, the first dielectric layer is a silicon oxide layer;
[0021] And / or, the thickness of the first dielectric layer is 0.1 nm to 5 nm;
[0022] And / or, the thickness of the second dielectric layer is 0.1 nm to 50 nm;
[0023] And / or, the third dielectric layer is a silicon oxide layer;
[0024] And / or, the thickness of the third dielectric layer is 0.1 nm to 5 nm;
[0025] And / or, the thickness of the first doped polysilicon layer is 50nm-500nm;
[0026] And / or, the thickness of the second doped polysilicon layer is 50 nm to 300 nm.
[0027] In a second aspect, an embodiment of the present application provides a photovoltaic module, comprising a passivated contact solar cell as described in the first aspect.
[0028] Compared with the prior art, the beneficial effects of the utility model are:
[0029] An embodiment of the present application provides a passivated contact solar cell. A second dielectric layer is arranged between a first doped polysilicon layer and a first electrode. The work function of the second dielectric layer is greater than the work function of the first doped polysilicon layer. This reduces the possibility of metal contact recombination at the interface between the first doped polysilicon layer and the first electrode, thereby improving the conversion efficiency of the passivated contact solar cell.
[0030] The passivated contact solar cell also arranges the first doped polysilicon layer in a local first region to reduce the area of the first doped polysilicon layer, thereby reducing the light parasitic absorption loss caused by the first doped polysilicon layer.
[0031] Finally, the doping concentration of the passivated contact solar cell in the second region is only 9×10 13 Pieces / cm 3 ~3×10 16 Pieces / cm 3 The doping concentration of the second region is low, which reduces the Auger recombination problem caused by the high doping concentration, so as to further improve the conversion efficiency of the passivated contact solar cell.
[0032] In summary, the passivated contact solar cell has the characteristics of less metal recombination, less light parasitic absorption, less Auger recombination and high conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0034] Figure 1 It is a schematic diagram of the structure of a passivated contact solar cell disclosed in an embodiment of the present application.
[0035] Description of Figure Numbers:
[0036] 100, passivated contact solar cell; 110, silicon substrate; 111, light-receiving surface; 1111, first region; 1112, second region; 112, backlight surface; 120, first dielectric layer; 130, first doped polysilicon layer; 140, second dielectric layer; 150, first electrode; 160, third dielectric layer; 170, second doped polysilicon layer; 180, second electrode; 190, functional layer; 191, aluminum oxide passivation film; 192, silicon nitride anti-reflection film. DETAILED DESCRIPTION
[0037] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0038] In the present invention, the term "on" is used in some cases to indicate a certain dependency or connection relationship. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.
[0039] In addition, the term "disposition" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements or components. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.
[0040] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components.
[0041] In the related art, the metal electrode is in contact with the heavily doped layer directly formed on the surface of the silicon substrate, that is, the metal electrode is in direct contact with the silicon substrate. The passivated contact solar cell with this structure has a large metal complex.
[0042] In order to avoid direct contact between the metal electrode and the silicon substrate, the related technology makes a passivation contact structure on the silicon substrate, that is, a dielectric layer and a doped polysilicon layer are stacked in sequence away from the silicon substrate, and then the metal electrode makes ohmic contact with the doped polysilicon layer to avoid the recombination loss caused by direct contact between the metal electrode and the silicon substrate. However, recombination will still occur at the contact point between the metal electrode and the doped polysilicon layer due to the large difference in the contact potential barrier between the two, which affects the conversion efficiency of the solar cell. In addition, there is a high contact resistance between the metal electrode and the doped polysilicon layer, which limits the current transmission efficiency of the battery.
[0043] Based on the above analysis, the present application provides a passivated contact solar cell, which provides a second dielectric layer between the first doped polysilicon layer and the first electrode. The work function of the second dielectric layer is greater than the work function of the first doped polysilicon layer, thereby reducing the possibility of metal contact recombination at the interface between the first doped polysilicon layer and the first electrode, thereby improving the conversion efficiency of the passivated contact solar cell.
[0044] The first aspect, such as Figure 1 As shown, the embodiment of the present application provides a passivated contact solar cell 100 , including a silicon substrate 110 , a first dielectric layer 120 , a first doped polysilicon layer 130 , a second dielectric layer 140 and a first electrode 150 .
[0045] The first doped polysilicon layer 130 has a first conductivity type, and the silicon substrate 110 has the first conductivity type or a second conductivity type opposite to the first conductivity type. Exemplarily, for example, the first doped polysilicon layer 130 is a P-type doped polysilicon layer or an N-type doped polysilicon layer, and the silicon substrate 110 can be an N-type silicon substrate or a P-type silicon substrate.
[0046] The silicon substrate 110 has a light receiving surface 111, and the light receiving surface 111 has a local first region 1111. The region of the light receiving surface 111 outside the first region 1111 is a second region 1112. The doping concentration of the second region 1112 is 9×10 13 Pieces / cm 3 ~3×10 16 Pieces / cm 3 Including any point value within the doping concentration range, for example, 9×10 13 Pieces / cm 3 , 1×10 16 Pieces / cm 3 or 3×10 16 Pieces / cm 3 It can be understood that for silicon substrates 110 of different conductivity types, the doping concentration range of the second region 1112 may be different. For example, when the silicon substrate 110 is a P-type silicon substrate, the doping concentration of the second region 1112 is further preferably 5×10 14 Pieces / cm3 ~3×10 16 Pieces / cm 3 When the silicon substrate 110 is an N-type silicon substrate, the doping concentration of the second region 1112 is further preferably 9×10 13 Pieces / cm 3 ~5×10 15 Pieces / cm 3 .
[0047] The first dielectric layer 120 , the first doped polysilicon layer 130 , the second dielectric layer 140 and the first electrode 150 are sequentially stacked on the first region 1111 in a direction away from the silicon substrate 110 , and the work function of the second dielectric layer 140 is greater than that of the first doped polysilicon layer 130 .
[0048] The passivated contact solar cell 100 is formed by adding a second dielectric layer 140 between the first doped polysilicon layer 130 and the first electrode 150. The functions of the second dielectric layer 140 are as follows:
[0049] First, the work function of the second dielectric layer 140 is selected to be greater than the work function of the first doped polysilicon layer 130. In other words, the second dielectric layer 140 has a stronger electron affinity, and the second dielectric layer 140 can further screen the majority carriers and minority carriers extracted from the silicon substrate 110 by the first doped polysilicon layer 130, thereby reducing the possibility of metal contact recombination at the contact interface between the first doped polysilicon layer 130 and the first electrode 150.
[0050] Secondly, the second dielectric layer 140 , which can further screen majority carriers and minority carriers, can reduce contact resistance, improve carrier transfer efficiency, and thus enhance the performance of the passivated contact solar cell 100 .
[0051] The passivated contact solar cell 100 further disposes the first doped polysilicon layer 130 in the local first region 1111 to reduce the coverage area of the first doped polysilicon layer 130 on the light receiving surface 111 , thereby reducing the light parasitic absorption loss caused by the first doped polysilicon layer 130 .
[0052] The doping concentration of the passivated contact solar cell 100 in the second region 1112 is only 9×10 13 Pieces / cm 3 ~3×10 16 Pieces / cm 3 , while the doping concentration in this area in the related art is not less than 1×10 18 Pieces / cm 3It is understandable that the second region 1112 is not heavily doped for the purpose of forming an emitter or a surface field layer. The second region 1112 has a low doping concentration, which reduces the Auger recombination problem caused by the high doping concentration, so as to further improve the conversion efficiency of the passivated contact solar cell 100 .
[0053] In summary, the passivated contact solar cell 100 has the characteristics of less metal recombination, less light parasitic absorption, less Auger recombination and high conversion efficiency.
[0054] Regarding the difference between the work function of the second dielectric layer 140 and the work function of the first doped polysilicon layer 130, firstly, the difference cannot be too small, so as to avoid that the improvement of the metal contact recombination problem after adding the second dielectric layer 140 is not obvious. Secondly, the difference between the work function cannot be too large, so as to avoid that it is difficult to select a material that meets the requirements to make the second dielectric layer 140. In the present application, the difference between the work function of the second dielectric layer 140 and the work function of the first doped polysilicon layer 130 is 0.1eV to 2eV, including any point value within the work function range, such as 0.1eV, 1eV or 2eV.
[0055] Optionally, the work function of the second dielectric layer 140 is 4.5 eV to 6.8 eV, including any point value within the work function range, for example, 4.5 eV, 5.0 eV, 6.0 eV or 6.8 eV;
[0056] And / or, the work function of the first doped polysilicon layer 130 is 4.0 eV to 5.5 eV, including any point value within the work function range, for example, 4.0 eV, 5.0 eV or 5.5 eV.
[0057] It should be noted that the work function of the first doped polysilicon layer 130 is related to the doping concentration, and the material of the second dielectric layer 140 depends on the doping concentration of the first doped polysilicon layer 130. Exemplarily, in one embodiment, the work function of the first doped polysilicon layer 130 at the doping concentration is 5.0 eV, molybdenum oxide is selected to make the second dielectric layer 140, and the work function of molybdenum oxide is 5.5 eV to 6.7 eV, and the obtained second dielectric layer 140 satisfies the phase difference of 0.1 eV to 2 eV with the work function of the first doped polysilicon layer 130. It can be understood that the present application does not involve improvements to the material of the second dielectric layer 140.
[0058] Preferably, the second dielectric layer 140 is a transition metal oxide layer. Compared with the use of high work function materials such as gold, palladium, platinum and other metal elements in the related art, the use of a transition metal oxide layer in the present application can reduce material costs, and the transition metal oxide is also easy to be made into a continuous film layer, for example, the second dielectric layer 140 is obtained by thermal evaporation or magnetron sputtering deposition.
[0059] Optionally, the material of the transition metal oxide layer is selected from any one of molybdenum oxide, vanadium oxide, tungsten oxide or copper oxide.
[0060] If the thickness of the second dielectric layer 140 is too thin, the selectivity of the second dielectric layer 140 for carriers is affected; if the thickness of the second dielectric layer 140 is too thick, the conductivity of the second dielectric layer 140 is reduced. Preferably, the thickness of the second dielectric layer 140 is 0.1 nm to 50 nm, including any value within the thickness range, for example, 0.1 nm, 10 nm or 50 nm.
[0061] In one of the embodiments of the present application, the widths of the first dielectric layer 120, the first doped polysilicon layer 130, the second dielectric layer 140 and the first electrode 150 are equal, which can avoid the problem of light parasitic absorption loss of the light receiving surface 111. This is because the first electrode 150 inevitably has a light shielding phenomenon, and the first doped polysilicon layer 130 does not cause light parasitic absorption loss within the coverage range of the first electrode 150. In the related art, the metal electrode forms an ohmic contact with the doped polysilicon layer by penetrating the anti-reflection layer and the passivation layer. In order to avoid the excessive burn-through area, the width of the metal electrode is less than the width of the doped polysilicon layer. In the present application, the first electrode 150 does not need to penetrate the functional layer 190 to make ohmic contact with the first doped polysilicon layer 130, and the first electrode 150 can be made by deposition to form a first electrode 150 with the same width as the first doped polysilicon layer 130.
[0062] In the related art, the high work function dielectric layer arranged between the doped polysilicon layer and the metal electrode is often a discontinuous film layer, resulting in the dielectric layer occupying only 10% to 80% of the area of the contact interface between the doped polysilicon layer and the metal electrode, which in turn results in the metal electrode portion still being in direct contact with the doped polysilicon layer. The contact potential barrier at the direct contact point is too different, resulting in a recombination phenomenon.
[0063] In the present application, the cross-sectional areas of the first doped polysilicon layer 130, the second dielectric layer 140 and the first electrode 150 are equal. It can be understood that the second dielectric layer 140 occupies 100% of the area of the contact interface between the first doped polysilicon layer 130 and the first electrode 150, and there is no direct contact between the first doped polysilicon layer 130 and the first electrode 150, thereby eliminating the recombination phenomenon caused by direct contact.
[0064] In some embodiments, the passivated contact solar cell 100 further includes a third dielectric layer 160, a second doped polysilicon layer 170, and a second electrode 180; the second doped polysilicon layer 170 has a second conductivity type;
[0065] The silicon substrate 110 further has a backlight surface 112 disposed opposite to the light receiving surface 111 . The third dielectric layer 160 , the second doped polysilicon layer 170 and the second electrode 180 are sequentially stacked on the backlight surface 112 in a direction away from the silicon substrate 110 .
[0066] The third dielectric layer 160 and the second doped polysilicon layer 170 constitute a backlight surface 112 passivation contact structure of the passivation contact solar cell 100 to further improve the performance of the passivation contact solar cell 100. The second electrode 180 is stacked on the second doped polysilicon layer 170 to form a contact and serve as the backlight surface electrode of the passivation contact solar cell 100.
[0067] In the related art, the passivation layer and the anti-reflection layer cover the entire light-receiving surface, which means that the metal electrode needs to penetrate the passivation layer and the anti-reflection layer to form an ohmic contact with the doped polysilicon layer. When manufacturing the passivation contact solar cell with the above structure, the silicon substrate needs to be sintered at a high temperature so that the slurry can burn through the passivation layer and the anti-reflection layer to form a metal electrode.
[0068] In some embodiments of the present application, the passivated contact solar cell 100 further includes a functional layer 190 disposed on the second region 1112. Exemplarily, the functional layer 190 includes an aluminum oxide passivation film 191 and a silicon nitride anti-reflection film 192 stacked away from the silicon substrate 110.
[0069] In the present application, the functional layer 190 is only set on the second area 1112, and the functional layer 190 is not set on the first area 1111. In order to form contact with the first doped polysilicon layer 130, the first electrode 150 does not need to penetrate the functional layer 190, and thus there is no need to perform high-temperature sintering on the silicon substrate 110, thereby reducing the damage to the silicon substrate 110 caused by high temperature and saving more energy.
[0070] Optionally, the silicon substrate 110 is an N-type silicon substrate, the first doped polysilicon layer 130 is a P-type doped polysilicon layer, the first electrode 150 is an aluminum electrode, the second doped polysilicon layer 170 is an N-type doped polysilicon layer, and the second electrode 180 is a silver electrode.
[0071] Compared with the contact between the silver electrode and the N-type doped polysilicon layer, the contact resistance between the aluminum electrode and the P-type doped polysilicon layer is often larger. On the one hand, this is because the passivation performance and contact characteristics of the first dielectric layer 120 and the P-type doped polysilicon layer are relatively poor. On the other hand, the contact barrier difference between the aluminum electrode and the P-type doped polysilicon layer is too large, resulting in more losses during carrier transmission and thus causing recombination at the interface. High contact resistance reduces the efficiency of carrier transmission at the contact between the metal and the semiconductor.
[0072] In view of the above phenomenon existing between the aluminum electrode and the P-type doped polysilicon layer, the present application adds the above second dielectric layer 140 between the aluminum electrode and the P-type doped polysilicon layer, thereby overcoming the contact barrier between the aluminum electrode and the P-type doped polysilicon layer. Since the work function of the second dielectric layer 140 is larger, it can effectively reduce the obstacles of electrons at this contact point, thereby improving the transmission efficiency of electrons, which is beneficial to improving the performance of the passivated contact solar cell 100 using the aluminum electrode in contact with the P-type doped polysilicon layer.
[0073] In the present application, the materials of the first dielectric layer 120 and the third dielectric layer 160 may include a variety of dielectric materials, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. Specifically, the first dielectric layer 120 and the third dielectric layer 160 may be composed of a silicon oxide layer containing silicon oxide. This is because the silicon oxide layer has excellent passivation properties, can minimize the recombination loss of minority carriers on the surface of the semiconductor substrate, and is a film with excellent durability to subsequent high-temperature processes.
[0074] The first dielectric layer 120 and the third dielectric layer 160, as a barrier for electrons and holes, can be combined with the first doped polysilicon layer 130 and the second doped polysilicon layer 170 to prevent minority carriers from passing through. The first dielectric layer 120 and the third dielectric layer 160 can also have a pinhole channel effect, so that the carriers in the passivated contact solar cell 100 can move freely, and the first doped polysilicon layer 130 and the second doped polysilicon layer 170 can be combined to produce selective passage of majority carriers, which is beneficial to reduce the recombination loss of minority carriers. In addition, the first dielectric layer 120 and the third dielectric layer 160 can be used as diffusion barriers to prevent the dopants of the first doped polysilicon layer 130 and the second doped polysilicon layer 170 from diffusing into the semiconductor substrate.
[0075] Preferably, the first dielectric layer 120 is a silicon oxide layer;
[0076] In order to better provide interface passivation for the silicon substrate 110 , the thickness of the first dielectric layer 120 is 0.1 nm to 5 nm, including any value within the thickness range, such as 0.1 nm, 3 nm or 5 nm.
[0077] Preferably, the third dielectric layer 160 is a silicon oxide layer;
[0078] In order to better provide interface passivation for the silicon substrate 110 , the thickness of the third dielectric layer 160 is 0.1 nm to 5 nm, including any value within the thickness range, such as 0.1 nm, 3 nm or 5 nm.
[0079] Preferably, the thickness of the first doped polysilicon layer 130 is 50 nm to 500 nm, including any value within the thickness range, for example, 50 nm, 250 nm or 500 nm;
[0080] And / or, the thickness of the second doped polysilicon layer 170 is 50 nm-300 nm, including any value within the thickness range, for example, 50 nm, 200 nm or 300 nm.
[0081] In a second aspect, an embodiment of the present application provides a photovoltaic module, comprising the passivated contact solar cell 100 as described in the first aspect.
[0082] The technical solution of the utility model will be described below in conjunction with embodiments and drawings.
[0083] Example 1
[0084] The present embodiment provides a passivated contact solar cell, including a silicon substrate, a first dielectric layer, a first doped polysilicon layer, a second dielectric layer, a first electrode, a functional layer, a third dielectric layer, a second doped polysilicon layer and a second electrode.
[0085] The silicon substrate has a light-receiving surface, and the light-receiving surface has a local first region. A first dielectric layer, a first doped polysilicon layer, a second dielectric layer and a first electrode are sequentially stacked on the first region in a direction away from the silicon substrate, the work function of the first doped polysilicon layer is 4.2eV, the material of the second dielectric layer is molybdenum oxide, and the work function of the second dielectric layer is 5.6eV.
[0086] The widths of the first dielectric layer, the first doped polysilicon layer, the second dielectric layer and the first electrode are equal. The cross-sectional areas of the first doped polysilicon layer, the second dielectric layer and the first electrode are equal.
[0087] The area of the light-receiving surface outside the first area is the second area, and the doping concentration of the second area is 1×10 15 Pieces / cm 3 The functional layer is disposed on the second region. The functional layer includes an aluminum oxide passivation film and a silicon nitride anti-reflection film stacked away from the silicon substrate.
[0088] The silicon substrate also has a backlight surface arranged opposite to the light-receiving surface, and the third dielectric layer, the second doped polysilicon layer and the second electrode are sequentially stacked on the backlight surface in a direction away from the silicon substrate.
[0089] The silicon substrate is an N-type silicon substrate, the first doped polysilicon layer is a P-type doped polysilicon layer, the first electrode is an aluminum electrode, the second doped polysilicon layer is an N-type doped polysilicon layer, and the second electrode is a silver electrode. The thickness of the second dielectric layer is 5 nm. The first dielectric layer and the third dielectric layer are silicon oxide layers. The thickness of the first dielectric layer is 2 nm. The thickness of the third dielectric layer is 1.5 nm. The thickness of the first doped polysilicon layer is 150 nm, and the thickness of the second doped polysilicon layer is 100 nm.
[0090] Example 2
[0091] The difference between this embodiment and Embodiment 1 is that the work function of the first doped polysilicon layer is 5.15 eV, and the difference between the work function of the second dielectric layer and the work function of the first doped polysilicon layer is 0.05 eV.
[0092] Example 3
[0093] The difference between this embodiment and Embodiment 1 is that the widths of the second dielectric layer and the first electrode are equal, but the widths of the second dielectric layer and the first electrode are smaller than the width of the first doped polysilicon layer.
[0094] Example 4
[0095] The only difference between this embodiment and Embodiment 1 is that the cross-sectional areas of the first doped polysilicon layer and the first electrode are equal, and the second dielectric layer occupies 85% of the area of the contact interface between the first doped polysilicon layer and the first electrode.
[0096] Comparative Example 1
[0097] The only difference between this comparative example and Example 1 is that no second dielectric layer is disposed between the first doped polysilicon layer and the first electrode.
[0098] Comparative Example 2
[0099] The difference between this comparative example and Example 1 is that the doping concentration of the second region is 1×10 18 Pieces / cm 3 .
[0100] Comparative Example 3
[0101] The difference between this comparative example and Example 1 is that the first dielectric layer, the first doped polysilicon layer and the second dielectric layer are sequentially stacked on the entire light-receiving surface, i.e., the first region and the second region, in a direction away from the silicon substrate. No aluminum oxide passivation film and silicon nitride anti-reflection film are provided on the second region of the light-receiving surface.
[0102] The passivated contact solar cells of each embodiment and each comparative example were tested, and the test results are shown in Table 1.
[0103] Table 1: Test results of the passivated contact solar cells of each embodiment and each comparative example
[0104]
[0105] As can be seen from Table 1, the conversion efficiency, fill factor, open circuit voltage, and short circuit current density of Examples 1-4 are higher than those of Comparative Examples 1-3 for the following reasons:
[0106] In Comparative Example 1, the second dielectric layer is not provided, the first doped polysilicon layer is in direct contact with the first electrode, and the metal composite between the first doped polysilicon layer and the first electrode is relatively large, resulting in low conversion efficiency.
[0107] In Comparative Example 2, although a second dielectric layer is provided between the first conductive layer and the first metal electrode, the doping concentration of the second region is too high, which aggravates the internal Auger recombination and increases the carrier recombination of the silicon substrate, directly affecting the conversion efficiency of the solar cell.
[0108] In comparative example 3, since the first doped polysilicon covers the light-receiving surface, the parasitic absorption loss of the light-receiving surface is large. In addition, due to the lack of an aluminum oxide passivation film and a silicon nitride anti-reflection film, the incident light loss increases and the solar cell conversion efficiency is low.
[0109] In Example 1-4, a second dielectric layer is disposed between the first doped polysilicon layer and the first electrode, and the work function of the second dielectric layer is greater than the work function of the first doped polysilicon layer, thereby reducing the metal contact recombination at the interface between the first doped polysilicon layer and the first electrode. In Example 1-4, the first doped polysilicon layer is also disposed in a local first region to reduce the area of the first doped polysilicon layer, thereby reducing the light parasitic absorption loss caused by the first doped polysilicon layer. In Example 1-4, the doping concentration of the second region is low, which reduces the Auger recombination problem caused by the high doping concentration, so as to further improve the conversion efficiency of the passivated contact solar cell.
[0110] Furthermore, the conversion efficiency, fill factor, open circuit voltage, and short circuit current density of Example 1 are higher than those of Examples 2-4, and the metal composite and contact resistance are lower than those of Examples 2-4, for the following reasons:
[0111] In Example 2, since the work function of the second dielectric layer is slightly different from that of the first doped polysilicon layer, the second dielectric layer has a weaker ability to further screen majority carriers and minority carriers, which causes the open circuit voltage of the solar cell to drop and the conversion efficiency to decrease.
[0112] In Example 3, the width of the second dielectric layer and the first electrode is smaller than that of the first doped polysilicon layer. The width of the first doped polysilicon layer is slightly wider. The protruding portion of the first doped polysilicon layer relative to the first electrode will affect part of the incident light on the light receiving surface, thereby causing the short-circuit current density to decrease.
[0113] In Example 4, the second dielectric layer occupies 85% of the area of the contact interface between the first doped polysilicon layer and the first electrode, that is, the second dielectric layer is not provided between part of the first doped polysilicon layer and part of the first electrode, resulting in partial direct contact between the two, thereby increasing metal recombination, causing the metal recombination and contact resistance of Example 4 to be higher than those of Examples 1-3, and the conversion efficiency, fill factor, open circuit voltage, and short-circuit current density of Example 4 to be lower than those of Examples 1-3.
[0114] Embodiment 1 ensures the ability of the second dielectric layer to further screen majority carriers and minority carriers by selecting the phase difference between the work function of the second dielectric layer and the work function of the first doped polysilicon layer. Embodiment 1 adopts a structure in which the second dielectric layer, the first electrode and the first doped polysilicon layer are of equal width, and the first doped polysilicon layer has no protruding part relative to the first electrode, thereby not affecting the incident light on the light-receiving surface. Embodiment 1 also adopts a structure in which the cross-sectional areas of the first doped polysilicon layer, the second dielectric layer and the first electrode are equal, and there is no direct contact between the first doped polysilicon layer and the first electrode, so that the metal composite is at a lower level. In summary, the conversion efficiency, fill factor, open circuit voltage, and short-circuit current density of Embodiment 1 are higher, and the metal composite and contact resistance are lower.
[0115] A passivated contact solar cell and photovoltaic module disclosed in an embodiment of the utility model are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the utility model. The description of the above embodiments is only used to help understand the passivated contact solar cell and photovoltaic module of the utility model and its core idea: At the same time, for general technical personnel in this field, according to the idea of the utility model, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the utility model.
Claims
1. A passivated contact solar cell, characterized in that: It includes a silicon substrate, a first dielectric layer, a first doped polysilicon layer, a second dielectric layer and a first electrode; The first doped polysilicon layer has a first conductivity type, and the silicon substrate has the first conductivity type or a second conductivity type opposite to the first conductivity type; The silicon substrate has a light-receiving surface, the light-receiving surface has a local first region, the region of the light-receiving surface outside the first region is a second region, and the doping concentration of the second region is 9×10 13 Pieces / cm 3 ~3×10 16 Pieces / cm 3 ; The first dielectric layer, the first doped polysilicon layer, the second dielectric layer and the first electrode are sequentially stacked on the first region in a direction away from the silicon substrate, and a work function of the second dielectric layer is greater than a work function of the first doped polysilicon layer.
2. The passivated contact solar cell according to claim 1, characterized in that: The work function of the second dielectric layer and the work function of the first doped polysilicon layer differ by 0.1 eV to 2 eV.
3. The passivated contact solar cell according to claim 1, characterized in that: The work function of the second dielectric layer is 4.5 eV to 6.8 eV; And / or, the work function of the first doped polysilicon layer is 4.0 eV to 5.5 eV.
4. The passivated contact solar cell according to claim 1, characterized in that: The second dielectric layer is a transition metal oxide layer.
5. The passivated contact solar cell according to claim 4, characterized in that: The material of the transition metal oxide layer is selected from any one of molybdenum oxide, vanadium oxide, tungsten oxide or copper oxide.
6. The passivated contact solar cell according to claim 1, characterized in that: The first dielectric layer, the first doped polysilicon layer, the second dielectric layer and the first electrode have equal widths; And / or, the cross-sectional areas of the first doped polysilicon layer, the second dielectric layer and the first electrode are equal.
7. The passivated contact solar cell according to any one of claims 1 to 6, characterized in that: The passivated contact solar cell further comprises a third dielectric layer, a second doped polysilicon layer and a second electrode; the second doped polysilicon layer has the second conductivity type; The silicon substrate further comprises a backlight surface which is arranged opposite to the light receiving surface, and the third dielectric layer, the second doped polysilicon layer and the second electrode are sequentially stacked on the backlight surface in a direction away from the silicon substrate.
8. The passivated contact solar cell according to any one of claims 1 to 6, characterized in that The passivated contact solar cell further comprises a functional layer arranged on the second region.
9. The passivated contact solar cell according to claim 7, characterized in that: The silicon substrate is an N-type silicon substrate, the first doped polysilicon layer is a P-type doped polysilicon layer, the first electrode is an aluminum electrode, the second doped polysilicon layer is an N-type doped polysilicon layer, and the second electrode is a silver electrode; And / or, the first dielectric layer is a silicon oxide layer; And / or, the thickness of the first dielectric layer is 0.1 nm to 5 nm; And / or, the thickness of the second dielectric layer is 0.1 nm to 50 nm; And / or, the third dielectric layer is a silicon oxide layer; And / or, the thickness of the third dielectric layer is 0.1 nm to 5 nm; And / or, the thickness of the first doped polysilicon layer is 50nm-500nm; And / or, the thickness of the second doped polysilicon layer is 50 nm to 300 nm.
10. A photovoltaic module, characterized in that: A solar cell comprising the passivated contact as claimed in any one of claims 1 to 9.