阅读说明：本技术 改善硅太阳能电池的接触格与发射极层之间的欧姆接触特性的方法 (Method for improving ohmic contact characteristics between contact grid and emitter layer of silicon solar cell ) 是由 赵宏明 于 2019-02-05 设计创作，主要内容包括：本发明涉及一种改善硅太阳能电池的接触格与发射极层之间的欧姆接触特性的方法,其中,将所述接触格与电压源的一个电极电连接,以及,将一个与所述电压源的另一电极电连接的接触装置同所述背触点连接,以及,通过所述电压源施加一个与所述硅太阳能电池的正向反向的小于所述硅太阳能电池的击穿电压的电压,以及,在存在所述电压的情况下,用点光源对所述面向太阳的一侧的某个分区的局部进行照明,从而在所述分区内感生电流,以及,所述电流就所述局部而言具有200A/cm<Sup>2</Sup>至20000A/cm<Sup>2</Sup>的电流密度且为时10ns至10ms地作用于所述分区。(The invention relates to a method for improving the ohmic contact behavior between a contact grid and an emitter layer of a silicon solar cell, wherein the contact grid is electrically connected to one electrode of a voltage source, and a contact device electrically connected to the other electrode of the voltage source is connected to the back contact, and a voltage which is less than the breakdown voltage of the silicon solar cell in the forward direction and in the reverse direction of the silicon solar cell is applied by the voltage source, and, in the presence of the voltage, the point light source is used to apply the voltage to the silicon solar cellA local part of a subarea of the sun-facing side is illuminated so that a current is induced in said subarea, and said current has 200A/cm for said local part 2 Up to 20000A/cm 2 And is applied to the partition in a time of 10ns to 10 ms.)

1. A method for improving the ohmic contact behavior between a contact lattice and an emitter layer of a silicon solar cell, characterized in that a silicon solar cell comprising an emitter layer, a contact lattice and a back contact is first provided, and the contact lattice is electrically connected to one electrode of a voltage source, and a contact means electrically connected to the other electrode of the voltage source is connected to the back contact, and a voltage which is smaller than the breakdown voltage of the silicon solar cell in the forward direction and in the reverse direction of the silicon solar cell is applied by the voltage source, and, in the presence of the voltage, a point light source is guided over the side of the silicon solar cell facing the sun and in the process illuminates a partial region of the side facing the sun, and thereby induces a current in the partial region, and, the current has 200A/cm for the local part²Up to 20000A/cm²And is applied to the partition in a time of 10ns to 10 ms.

2. The method of claim 1,

the point light source is a laser, a light emitting diode or a flash lamp.

3. The method of claim 1,

the point light source has 500W/cm on the local part²Up to 200000W/cm²The power density of (a).

4. The method of claim 1,

the point light source emits radiation having a wavelength in the range of 400nm to 1500 nm.

5. The method of claim 1,

the area of the part is 1-10³μm²To 1.10⁴μm²。

6. The method of claim 1,

the voltage in the forward direction and the reverse direction of the silicon solar cell is 1V to 20V.

7. The method of claim 1,

the point light sources are guided in the region of the side of the silicon solar cell facing the sun in the immediate vicinity of the contact fingers of the contact lattice.

8. The method of claim 1,

the silicon solar cell adopts a single-sided or double-sided structure.

9. The method of claim 1,

the silicon solar cell has an n-doped or p-doped silicon substrate.

10. The method of claim 1,

the emitter layer has a layer resistance higher than 100 Ohm/sq.

Technical Field

The invention relates to a method for improving the ohmic contact properties between a contact grid and an emitter layer of a silicon solar cell.

Background

For contacting crystalline silicon solar cells, a metal paste in the form of contact grids is applied to the front end of the dielectric-coated silicon nitride in a screen printing process. After the application is completed, the metal paste is fired into the silicon nitride at 800-900 ℃ to form electrical contact with the emitter layer. The process control during firing of the metal paste has a decisive influence on the contact formation, wherein a defective process control leads to a high contact resistance at the transition between the metal paste and the emitter layer of the silicon solar cell. In this case, high contact resistance may impair the efficiency of the silicon solar cell.

Disclosure of Invention

The object of the invention is to improve a method for improving the ohmic contact behavior between a contact grid and an emitter layer of a silicon solar cell, in order to further minimize the material influence on the side facing the sun that is illuminated. Another object is to apply the method to silicon solar cells with emitter layers having a higher layer resistance.

The solution of the present invention to achieve the above object is to provide a light emitting diode comprising an emitter layer, a contact grid and a back contactA silicon solar cell, and electrically connecting the contact grid with one electrode of a voltage source. The other electrode of the voltage source is electrically connected to a contact device attached to the back contact. Subsequently, a voltage is applied by the voltage source in the reverse direction of the silicon solar cell that is less than the breakdown voltage of the silicon solar cell. In the presence of this voltage, the point light source is guided over the side of the silicon solar cell facing the sun, in the process of which a partial area of the side facing the sun is illuminated. Thereby inducing a current in the partition, the current having a current of 200A/cm with respect to the local portion²Up to 20000A/cm²And is applied to the partition in a time of 10ns to 10 ms.

The inventive method makes it possible to compensate for defective process control during firing of the metal paste, so that the solar cell has an optimum series resistance for its structure. Furthermore, excellent ohmic contact characteristics between the contact grid and the emitter layer can be achieved on an emitter layer having a higher layer resistance by the method of the present invention, thus eliminating the need for processing steps required to construct a selective emitter. In addition, the method of the present invention can also be applied to perform the firing process at a lower temperature, thereby achieving energy saving in the manufacturing process of silicon solar cells.

The invention provides that the point light source is a laser, a light emitting diode or a flash lamp.

In one embodiment, the point light source has 500W/cm on the local portion²Up to 200000W/cm²The power density of (a).

According to one embodiment, the point source emits radiation in the wavelength range of 400nm to 1500 nm.

In another embodiment, the area of the local area is 1 · 10³μm²To 1.10⁴μm²。

The invention proposes that the voltage in the forward direction and the reverse direction of the silicon solar cell is between 1V and 20V.

The invention further provides that the point light sources are guided in the region of the side of the silicon solar cell facing the sun in the immediate vicinity of the contact fingers of the contact lattice.

In one embodiment, the silicon solar cell is in a single-sided or double-sided configuration.

In another embodiment, the silicon solar cell has an n-doped or p-doped silicon substrate.

According to one solution, the emitter layer has a layer resistance higher than 100 Ohm/sq.

Drawings

Detailed Description

The following describes embodiments of the present invention.

A crystalline silicon solar cell is first provided. The silicon solar cell has an antireflection layer of silicon nitride on its side facing the sun. An emitter layer of the silicon solar cell is arranged below this antireflection layer. On the sun-facing side, a front metallization layer in the form of a contact grid is printed, which consists of contact fingers and collective contacts (busbars) consisting of a commercially available metal paste, such as silver paste, which is hardened according to the manufacturing procedure and fired in a silicon nitride layer. On this side facing the sun, the silicon solar cells are provided with back contacts. This back contact consists of a metal layer, which may or may not be passivated (PERC solution).

Electrically connecting the contact grid with one electrode of a voltage source. Connecting the other electrode of the voltage source to a contact means connected to the back contact. Subsequently, a voltage is applied by the voltage source in the reverse direction of the silicon solar cell that is less than the breakdown voltage of the silicon solar cell. In the presence of this voltage, the point light source is guided over the side of the silicon solar cell facing the sun. The point light source may be, for example, a focused radiation of a laser, a light emitting diode or a flash lamp. The invention is not limited to these radiation sources. The point light source emits radiation having a wavelength in the range of 400nm to 1500 nm. The local illumination of a partial region of the side of the silicon solar cell facing the sun is carried out by the point light source, so that the partial region is illuminatedA current is induced in the region. The current has a current of 200A/cm for the local region²Up to 20000A/cm²And is applied to the partition in a time of 10ns to 10 ms.

The high current density required for improving the ohmic contact properties between the contact lattice and the emitter layer can be achieved in particular by moving the operating point of the illuminated cell region without causing radiation-induced material damage. The radiation density, the duration of action of the radiation source on the part and the applied voltage are combined to achieve the desired current density without the need to generate radiation that can damage the material. With an applied voltage of about 10V, a current of an intensity of 50mA to 600mA is typically generated at a radiated local portion having a diameter of about 60 μm, and thus, in terms of the area of the radiated local portion, there may be an order of 200A/cm²Up to 20000A/cm²The current density of (a) is effected. The absolutely flowing current is kept at a low level in particular by the relatively small area local to the radiation.

When scanning the side of the silicon solar cell facing the sun, in principle only the point light sources need to be moved next to the left and right of the contact fingers. Thus, the process time for processing a 6 "cell by the method of the present invention is in the range of one second.

In another embodiment, certain silicon solar cells are treated with the method of the present invention with the contact fingers fired at a temperature lower than that suggested by the manufacturer of the metal paste. Firing is typically carried out at a temperature in the range of 800 ℃. If the metal paste is fired only at a temperature of, for example, 700 c, the silicon solar cell has a higher contact resistance at the transition between the contact grid and the emitter layer. On silicon solar cells of this type, the ohmic contact properties between the contact lattice and the emitter layer can likewise be improved by the method according to the invention. If the method according to the invention is combined with a firing process which is carried out at a lower temperature, the same contact resistance can be achieved at the transition between the contact grid and the emitter layer while saving energy.

The method of the invention can be applied to single-sided silicon solar cells and double-sided silicon solar cells. In relation to the latter, only a single-sided treatment is sufficient for optimizing the contacts on both sides.

In another embodiment, certain silicon solar cells are processed with non-selective solutions for emitter layers and thus higher overall layer resistance (above 100 Ohm/sq). As already mentioned, these silicon solar cells are likewise printed with a metal paste and subsequently subjected to a firing process, wherein here again the firing process can be carried out according to the manufacturer data mentioned above or at a lower temperature. After the firing process, the silicon solar cell has only a relatively high-ohmic contact resistance at the transition between the contact grid and the emitter layer. By using the method according to the invention, even on these silicon solar cells, the radiation density of the radiation source at the location, the action time and the applied voltage are combined to reduce the contact resistance and the required value for optimum operation of the silicon solar cells. Thus, a selective emitter is not necessary, so that a complicated manufacturing process thereof can be omitted.