CN220821575U - Battery structure and photovoltaic module - Google Patents

Abstract

The utility model relates to a battery structure and photovoltaic module, battery structure, include: a silicon substrate comprising a front side and a back side; the tunneling layer covers the back surface of the silicon substrate; the first semiconductor doping layer covers the bottom surface of the tunneling layer; the first passivation layer covers the bottom surface of the first semiconductor doping layer and comprises a silicon oxide layer; the first antireflection layer covers the bottom surface of the first passivation layer and comprises at least one silicon nitride layer, so that the requirement of the battery structure on light transmittance can be met, and the passivation effect of the back surface of the battery structure can be further improved.

Description

Battery structure and photovoltaic module

Technical Field

The application relates to the technical field of solar cells, in particular to a cell structure and a photovoltaic module.

Background

Currently, in order to improve the performance of a solar cell, plating layers having different forms are formed on the front and back surfaces of the solar cell, for example, passivation layers are formed on the front and back surfaces of the cell to reduce the recombination rate and improve the carrier lifetime.

In order to ensure the photoelectric conversion efficiency of the solar cell, silicon nitride is generally selected as the passivation layer on the back surface of the solar cell, however, the passivation effect, film forming quality and high temperature stability of the silicon nitride are relatively poor, and how to improve the passivation effect of the passivation layer on the back surface of the solar cell becomes a problem to be solved.

Disclosure of Invention

Based on this, it is necessary to provide a cell structure and a photovoltaic module for the problems of relatively poor surface passivation effect, film formation quality and high temperature stability of the back passivation layer of the solar cell in the prior art.

In order to achieve the above object, in a first aspect, the present invention provides a battery structure, comprising:

A silicon substrate comprising a front side and a back side;

a tunneling layer covering the back surface of the silicon substrate;

The first semiconductor doping layer covers the bottom surface of the tunneling layer;

a first passivation layer covering a bottom surface of the first semiconductor doped layer, the first passivation layer including a silicon oxide layer;

And the first antireflection layer covers the bottom surface of the first passivation layer and comprises at least one silicon nitride layer.

In one embodiment, the refractive index of the first anti-reflective layer is greater than the refractive index of the first passivation layer.

In one embodiment, the refractive index of at least one of the silicon nitride layers decreases gradually in a direction away from the first passivation layer.

In one embodiment, at least one of the silicon nitride layers is doped with hydrogen ions, and the doping concentration of the hydrogen ions in at least one of the silicon nitride layers gradually decreases in a direction away from the first passivation layer.

In one embodiment, the first anti-reflection layer includes a first silicon nitride layer, a second silicon nitride layer, and a third silicon nitride layer stacked on a bottom surface of the first passivation layer.

In one embodiment, the thickness of the first passivation layer is 3nm-4nm.

In one embodiment, the battery structure further comprises:

the emitter is positioned on the front surface of the silicon substrate;

And the second passivation layer covers the top surface of the emitter, and the contact surface of the second passivation layer and the emitter forms ohmic contact.

In one embodiment, the second passivation layer includes at least an aluminum oxide layer disposed on the top surface of the emitter and connected to the top surface of the emitter.

In one embodiment, the first semiconductor doped layer has an N-type conductivity and the emitter has a P-type conductivity.

In a second aspect, the present invention provides a photovoltaic module comprising a cell structure according to the first aspect of the present invention.

The utility model discloses a battery structure and photovoltaic module, first passivation layer and first reflection-reducing layer range upon range of the back that sets up at the silicon substrate, first passivation layer have good surface passivation effect, film forming quality and high temperature stability's characteristics, and first reflection-reducing layer has good passivation effect and printing opacity effect, so, can satisfy the requirement of battery structure to the printing opacity, can also further promote the passivation effect at battery structure back.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments or the conventional techniques of the present application, the drawings required for the descriptions of the embodiments or the conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.

Fig. 1 is a schematic structural view of a battery structure provided in an embodiment.

Fig. 2 is a schematic structural view of a battery structure provided in an embodiment.

Fig. 3 is a schematic structural view of a battery structure provided in an embodiment.

Reference numerals illustrate:

1. A silicon substrate; 1a, front face; 1b, back surface; 2. a tunneling layer; 3. a first semiconductor doped layer; 4. a first passivation layer; 5. a first anti-reflection layer; 51. a first silicon nitride layer; 52. a second silicon nitride layer; 53. a third silicon nitride layer; 6. an emitter; 7. a second passivation layer; 71. an alumina layer; 72. a silicon nitride passivation layer; 73. a silicon oxynitride passivation layer; 74. and a silicon oxide passivation layer.

Detailed Description

In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

In the related art, in order to ensure the photoelectric conversion efficiency of the solar cell, silicon nitride is generally selected as the passivation layer on the back surface of the solar cell, however, the passivation effect, film forming quality and high temperature stability of the silicon nitride are relatively poor, and how to improve the passivation effect of the passivation layer on the back surface of the solar cell becomes a problem to be solved.

In order to solve the technical problems, the application provides a battery structure, which comprises a silicon substrate, a tunneling layer, a first semiconductor doping layer, a first passivation layer and a first anti-reflection layer; the silicon substrate comprises a front surface and a back surface, the tunneling layer, the first semiconductor doping layer, the first passivation layer and the first antireflection layer are sequentially arranged on the back surface of the silicon substrate, wherein the first passivation layer comprises a silicon oxide layer, and the first antireflection layer comprises at least one silicon nitride layer. According to the battery structure, the first passivation layer arranged on the back surface of the silicon substrate comprises the silicon oxide layer, the first anti-reflection layer arranged on the bottom surface of the first passivation layer comprises at least one silicon nitride layer, the silicon oxide is utilized to have the characteristics of good surface passivation effect, film forming quality and high-temperature stability, and the silicon nitride is utilized to have good passivation effect and light transmission effect, so that the first passivation layer and the first anti-reflection layer are arranged on the back surface of the silicon substrate in a stacked mode, the requirement of the battery structure on light transmission can be met, and the passivation effect of the back surface of the battery structure can be further improved.

According to an exemplary embodiment, the present embodiment provides a cell structure, which is applied to a photovoltaic cell, for example, may be applied to a cell such as PERC (Passivated Emitter RearCell), TOPCON (Tunnel Oxide Passivated Contact) or IBC (Interdigitated BackContact), and as shown in fig. 1, the cell structure of the present embodiment includes a silicon substrate 1, a tunneling layer 2, a first semiconductor doped layer 3, a first passivation layer 4 and a first anti-reflection layer 5, the silicon substrate 1 may be an N-type substrate or a P-type substrate, the silicon substrate 1 includes a front surface 1a and a back surface 1b, and the front surface 1a and the back surface 1b of the silicon substrate 1 are disposed opposite to each other. The tunneling layer 2 covers the back surface 1b of the silicon substrate 1, the material of the tunneling layer 2 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride, the first semiconductor doping layer 3 covers the bottom surface of the tunneling layer 2, the first semiconductor doping layer 3 is a conductive layer, the first semiconductor doping layer 3 has an N-type conductivity type or a P-type conductivity type, the first semiconductor doping layer 3 and the silicon substrate 1 have the same conductivity type, and the material of the first semiconductor doping layer 3 may include at least one of amorphous silicon, polysilicon, or silicon carbide; the first passivation layer 4 covers the bottom surface of the first semiconductor doping layer 3, and the first passivation layer 4 includes a silicon oxide layer; the first antireflection layer 5 covers the bottom surface of the first passivation layer 4, the first antireflection layer 5 comprises at least one silicon nitride layer, the silicon oxide layer of the first passivation layer 4 has good surface passivation effect, film forming quality and high-temperature stability, the silicon nitride layer of the first antireflection layer 5 has good passivation effect, the first passivation layer 4 and the first antireflection layer 5 are arranged on the back surface 1b of the silicon substrate 1 in a stacked mode, good passivation effect is achieved on the back surface 1b of the silicon substrate 1, defect state density of the back surface 1b of the silicon substrate 1 is reduced, carrier recombination of the back surface 1b of the silicon substrate 1 is well restrained, meanwhile, the silicon nitride layer of the first antireflection layer 5 has good light transmittance, the first antireflection layer 5 has good antireflection effect, reflection of the back surface 1b of the silicon substrate 1 on incident light is reduced, and utilization rate of a battery structure on the incident light is improved.

In some embodiments, the first anti-reflection layer 5 may be a single layer structure, and the first anti-reflection layer 5 includes only one silicon nitride layer.

In some embodiments, the first anti-reflection layer 5 may also include a multi-layer structure sequentially stacked on the bottom surface of the first passivation layer 4, at least one layer in the multi-layer structure is a silicon nitride layer, and the material of the other layers in the multi-layer structure may include at least one of silicon nitride, silicon oxynitride, or aluminum oxide; the materials of the layers in the multilayer structure may be different from each other, or a part of the number of layers may be different from each other, and the remaining part of the number of materials may be the same. For example, the first anti-reflection layer 5 may be a multilayer structure of a silicon nitride layer and an aluminum oxide layer.

The manufacturing process of the battery structure needs to be subjected to high-temperature sintering for several times, or the working environment of the battery structure can be in a high-temperature environment, the silicon oxide layer has good high-temperature stability, and the passivation effect on the back surface of the battery structure in the high-temperature environment can be improved. The silicon oxide layer and the first semiconductor doped layer 3 have good lattice matching performance, the film layer of the silicon oxide layer is high in density, the surface passivation effect, the film forming quality and the high-temperature stability performance are good, and the first passivation layer 4 is arranged on the back surface 1b of the silicon substrate 1, so that good protection can be formed on the back surface 1b of the silicon substrate 1. The silicon nitride layer of the first anti-reflection layer 5 has good light transmittance and passivation effect.

According to the embodiment, the first passivation layer 4 is arranged between the first antireflection layer 5 and the first semiconductor doped layer 3, the first antireflection layer 5 is combined with the first semiconductor doped layer 3 through the first passivation layer 4, so that the bonding force between the first antireflection layer 5 and the first semiconductor doped layer 3 can be improved, the first antireflection layer 5 and the first semiconductor doped layer 3 are firmly combined together, the film layer on the back surface of the battery structure can be prevented from falling off, and meanwhile, the first passivation layer 4 and the first antireflection layer 5 form protection on the back surface of the battery structure, the passivation effect on the back surface of the battery structure is enhanced, and the back surface of the battery structure is prevented from being corroded and damaged.

In some embodiments, as shown in fig. 1, the refractive index of the first anti-reflection layer 5 is greater than that of the first passivation layer 4, and the first anti-reflection layer 5 has good light transmittance, so as to ensure the transmittance of light passing through the first anti-reflection layer 5, so as to improve the light receiving rate of the battery structure, and the battery structure generates a volt effect to form an electromotive force.

The thickness of the first passivation layer 4 is not limited in this embodiment, and appropriately increasing the thickness of the first passivation layer 4 can enhance the protection effect on the back surface of the battery structure and can further enhance the bonding force between the first anti-reflection layer 5 and the first semiconductor doping layer 3. However, the refractive index of the first passivation layer 4 is small, light transmittance is poor, and an increase in the thickness of the first passivation layer 4 may affect the light receiving rate of the cell structure.

In some embodiments, as shown in fig. 1, the thickness of the first passivation layer 4 is 3nm-4nm, so that the protection effect of the first passivation layer 4 and the first anti-reflection layer 5 on the back surface of the battery structure is improved, and the influence of the first passivation layer 4 on the light receiving rate of the battery structure is avoided as much as possible. For example, the thickness of the first passivation layer 4 may be 3nm, 3.1nm, 3.2nm, 3.3nm, 3.4nm, 3.5nm, 3.6nm, 3.7nm, 3.8nm, 3.9nm or 4nm.

The thickness of the first anti-reflection layer 5 is not limited in this embodiment, and the thickness of the first anti-reflection layer 5 may be 75nm to 90nm, for example, the thickness of the first anti-reflection layer 5 may be 75nm, 77nm, 79nm, 81nm, 93nm, 85nm, 87nm, 99nm or 90nm, based on the stability of the film layer of the battery structure and the passivation effect of the back surface of the battery structure.

The number of layers of the first anti-reflection layer 5 is not limited in this embodiment, and the first anti-reflection layer 5 may have a single-layer or multi-layer structure, for example, the first anti-reflection layer 5 may include only one silicon nitride layer, or the first anti-reflection layer 5 may include two or more silicon nitride layers sequentially stacked under the bottom surface of the first passivation layer 4.

In some embodiments, as shown in fig. 1, the refractive index of at least one silicon nitride layer gradually decreases in a direction away from the first passivation layer 4. The first anti-reflection layer 5 may include only one silicon nitride layer, and the refractive index of the silicon nitride layer gradually becomes smaller in a direction away from the first passivation layer 4, that is, the refractive index of the incident surface of the light in the first anti-reflection layer 5 is minimum; or the first anti-reflection layer 5 may include a plurality of silicon nitride layers having refractive indexes stepwise decreasing in a direction away from the first passivation layer 4, that is, having refractive indexes of incident layers of light rays in the first anti-reflection layer 5 minimum. In this way, the reflection amount of the light incident on the first antireflection layer 5 can be reduced, and more light can be transferred to the silicon substrate 1 for photoelectric conversion.

Meanwhile, in the battery structure of the embodiment, when performing photoelectric conversion, along the incident path of the light incident from the first anti-reflection layer 5 to the back surface 1b of the silicon substrate 1, the refractive index of the light passing through the first anti-reflection layer 5 is gradually increased, so that the direction of the light incident to the back surface 1b of the silicon substrate 1 can be adjusted through the transfer of the first anti-reflection layer 5, so that the light perpendicularly enters the back surface 1b of the silicon substrate 1, and the photoelectric conversion efficiency of the battery structure is further increased.

It will be appreciated that in forming the first anti-reflection layer 5, the refractive index of the formed silicon nitride layer may be adjusted by adjusting the process parameters of forming the silicon nitride layer, so that the silicon nitride layers in different layers have different refractive indexes. For example, in forming the first anti-reflection layer 5, at least one silicon nitride layer is formed using silane (SiH ₄) and ammonia (NH ₃) as gas sources by a plasma enhanced chemical vapor deposition process, and the refractive index of the at least one silicon nitride layer is gradually decreased in a direction away from the first passivation layer 4 by increasing the proportion of silane to increase the refractive index of the silicon nitride layer and decreasing the proportion of silane to decrease the refractive index of the silicon nitride layer.

In some embodiments, as shown in fig. 1, at least one silicon nitride layer is doped with hydrogen ions, and the doping concentration of the hydrogen ions in the at least one silicon nitride layer gradually decreases in a direction away from the first passivation layer 4. It is possible that the doping concentration of the hydrogen ions becomes gradually smaller in a direction away from the first passivation layer 4; or may be a stepwise decrease in the doping concentration of hydrogen ions in the multi-layered silicon nitride layer in a direction away from the first passivation layer 4.

The surface of the silicon substrate 1 may have defects such as pits or scratches, etc., where silicon dangling bonds are accumulated on the surface of the silicon substrate 1. In this example, the concentration of hydrogen ions in the silicon nitride layer of the first anti-reflection layer 5 near the first passivation layer 4 is the highest, and the hydrogen ions in the silicon nitride layer can neutralize the silicon dangling bonds accumulated on the back surface 1b of the silicon substrate 1, so as to avoid that the passivation effect of the back surface 1b of the silicon substrate 1 is affected by the free silicon dangling bonds.

In the process of forming the first anti-reflection layer 5, the content of hydrogen ions in the formed silicon nitride layer may be adjusted by adjusting the process parameters of forming the silicon nitride layer, for example, by increasing the proportion of silane to increase the content of hydrogen ions in the silicon nitride layer and decreasing the proportion of silane to decrease the content of hydrogen ions in the silicon nitride layer, thereby realizing that the doping concentration of hydrogen ions in at least one silicon nitride layer gradually decreases in the direction away from the first passivation layer 4.

According to an exemplary embodiment, as shown in fig. 2, the present embodiment provides a battery structure including a silicon substrate 1, a tunneling layer 2, a first semiconductor doping layer 3, a first passivation layer 4, and a first anti-reflection layer 5; the silicon substrate 1 includes a front surface 1a and a back surface 1b which are disposed opposite to each other, and a tunneling layer 2, a first semiconductor doping layer 3, a first passivation layer 4 and a first anti-reflection layer 5 are sequentially disposed on the back surface 1b of the silicon substrate 1 in this order, wherein the first passivation layer 4 includes a silicon oxide layer, the thickness of the first passivation layer 4 is 3nm to 4nm, and the first anti-reflection layer 5 includes a first silicon nitride layer 51, a second silicon nitride layer 52 and a third silicon nitride layer 53 which are disposed on the bottom surface of the first passivation layer 4 in a stacked manner.

The refractive index of the first silicon nitride layer 51 is n1, the refractive index of the second silicon nitride layer 52 is n2, the refractive index of the third silicon nitride layer 53 is n3, and n1 > n2 is greater than n3.

The content of hydrogen ions in the first silicon nitride layer 51 > the content of hydrogen ions in the second silicon nitride layer 52 > the content of hydrogen ions in the third silicon nitride layer 53.

In some examples, the refractive index n1 of the first silicon nitride layer 51 is 2.2-2.3, the refractive index n2 of the second silicon nitride layer 52 is 2.1-2.2, and the refractive index n3 of the third silicon nitride layer 53 is 2.0-2.1. It will be appreciated that the numerical ranges of the first silicon nitride layer 51, the second silicon nitride layer 52, and the second silicon nitride layer 52, although having overlapping regions, may be selected to ensure that n1 > n2 is greater than n 3.

In some embodiments, the thicknesses of the first silicon nitride layer 51, the second silicon nitride layer 52, and the third silicon nitride layer 53 may be the same.

In some embodiments, the thickness of the first silicon nitride layer 51 is less than the thickness of the second silicon nitride layer 52, and the thickness of the second silicon nitride layer 52 is less than the thickness of the third silicon nitride layer 53. For example, the thickness of the first silicon nitride layer 51 ranges from 15nm to 20nm, the thickness of the second silicon nitride layer 52 ranges from 25nm to 30nm, and the thickness of the Sam-th silicon nitride layer 53 ranges from 30nm to 40nm.

In the process of photoelectric conversion, light is incident to the back surface 1b of the silicon substrate 1 along the directions of the third silicon nitride layer 53, the second silicon nitride layer 52 and the first silicon nitride layer 51, and the reflectivity of the third silicon nitride layer is the smallest, so that the light reflected by the first anti-reflection layer 5 increases the amount of light incident to the silicon substrate 1 and increases the photoelectric conversion efficiency of the cell structure. The refractive index of the light passing through the third silicon nitride layer 53, the second silicon nitride layer 52 and the first silicon nitride layer 51 is sequentially increased, so that more light entering the back surface 1b of the silicon substrate 1 obliquely is converted into vertical incidence, the amount of light entering the silicon substrate 1 vertically is increased, and the photoelectric conversion efficiency of the cell structure is further increased.

In the battery structure of this embodiment, the first passivation layer 4 is disposed between the first anti-reflection layer 5 and the first semiconductor doped layer 3, so as to improve the passivation effect of the back surface 1b of the silicon substrate 1, and meanwhile, the first passivation layer 4 enhances the bonding strength between the first anti-reflection layer 5 and the first semiconductor doped layer 3, so as to avoid the first anti-reflection layer 5 from falling off. Meanwhile, when the battery structure is in a heating state or in a high-temperature environment, bubbles may be generated by outward diffusion of hydrogen ions in the first anti-reflection layer 5, particularly, the hydrogen ions in the first silicon nitride layer 51 diffuse in the direction of the first semiconductor doping layer 3 and generate bubbles, the first passivation layer 4 has good high-temperature stability, the bubbles generated by the first silicon nitride layer 51 can be isolated, the bubbles are prevented from extruding the first semiconductor doping layer 3 to cause the first semiconductor doping layer 3 to fall off, and the structural stability and the working stability of the film layer of the back surface 1b of the silicon substrate 1 are improved.

In some embodiments, as shown in fig. 1, 2 or 3, the battery structure further includes an emitter 6 and a second passivation layer 7, the emitter 6 is located on the front surface 1a of the silicon substrate 1, the emitter 6 has a P-type conductivity, the emitter 6 and the substrate 1 form a PN junction, the second passivation layer 7 covers the top surface of the emitter 6, and the contact surface of the second passivation layer 7 and the emitter 6 forms an ohmic contact.

In some embodiments, as shown in fig. 3, the second passivation layer 7 includes at least an aluminum oxide layer 71 disposed on the top surface of the emitter electrode 6 and connected to the top surface of the emitter electrode 6. The second passivation layer 7 may further include a silicon nitride passivation layer 72, a silicon oxynitride passivation layer 73, and a silicon oxide passivation layer 74 stacked on the aluminum oxide layer 71. The front and the back of the battery structure of this embodiment have good passivation effect and light transmittance, the first passivation layer 4 and the first anti-reflection layer 5 form good protection to the back of the battery structure, and the second passivation layer 7 forms good protection to the front of the battery structure, so that the surface passivation effect of the battery structure is improved.

In some embodiments, as shown in fig. 1, 2 or 3, the cell structure further comprises a plurality of front gate line electrodes 101 located on a side of the second passivation layer 7 facing away from the substrate 1, the front gate line electrodes 101 being in contact with the emitter electrode 6 through the second passivation layer 7. The material of the front gate line electrode 101 may include silver or aluminum.

In some embodiments, as shown in fig. 1, 2 or 3, the cell structure further comprises a plurality of back gate line electrodes 201 located on a side of the first anti-reflection layer 5 facing away from the substrate 1, the back gate line electrodes 201 extending through the first anti-reflection layer 5 and the first passivation layer 4 into the first semiconductor doped layer 3, the back gate line electrodes 201 being in contact through the first anti-reflection layer 5, the first passivation layer 4 and the first semiconductor doped layer 3. The material of the back gate line electrode 201 may include silver or aluminum.

According to an exemplary embodiment, a photovoltaic module is provided, which includes the battery structure in the above embodiment, and the photovoltaic module of this embodiment has good passivation effect and photoelectric conversion efficiency.

The technical features of the above embodiments may be arbitrarily combined, and for brevity, all of the possible combinations of the technical features of the above embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (10)

1. A battery structure, characterized by comprising:

A silicon substrate comprising a front side and a back side;

a tunneling layer covering the back surface of the silicon substrate;

The first semiconductor doping layer covers the bottom surface of the tunneling layer;

a first passivation layer covering a bottom surface of the first semiconductor doped layer, the first passivation layer including a silicon oxide layer;

And the first antireflection layer covers the bottom surface of the first passivation layer and comprises at least one silicon nitride layer.

2. The cell structure of claim 1, wherein the refractive index of the first anti-reflective layer is greater than the refractive index of the first passivation layer.

3. The cell structure of claim 1, wherein the refractive index of at least one of the silicon nitride layers decreases gradually in a direction away from the first passivation layer.

4. The cell structure of claim 1 wherein at least one of said silicon nitride layers is doped with hydrogen ions, the doping concentration of hydrogen ions in at least one of said silicon nitride layers decreasing in a direction away from said first passivation layer.

5. The cell structure of claim 3 or 4, wherein the first anti-reflection layer comprises a first silicon nitride layer, a second silicon nitride layer, and a third silicon nitride layer stacked on a bottom surface of the first passivation layer.

6. The cell structure of claim 3 or 4, wherein the first passivation layer has a thickness of 3nm-4nm.

7. The battery structure of claim 1, wherein the battery structure further comprises:

the emitter is positioned on the front surface of the silicon substrate;

And the second passivation layer covers the top surface of the emitter, and the contact surface of the second passivation layer and the emitter forms ohmic contact.

8. The cell structure of claim 7, wherein the second passivation layer comprises at least an aluminum oxide layer disposed on and coupled to the top surface of the emitter.

9. The battery structure of claim 7, wherein the first semiconductor doped layer has an N-type conductivity and the emitter has a P-type conductivity.

10. A photovoltaic module comprising the cell structure of any one of claims 1-9.