KR20120042589A

KR20120042589A - Solar cell have two emitter electrode

Info

Publication number: KR20120042589A
Application number: KR1020100104948A
Authority: KR
Inventors: 김한식
Original assignee: 김한식
Priority date: 2010-10-23
Filing date: 2010-10-26
Publication date: 2012-05-03

Abstract

PURPOSE: A solar cell which includes two emitter electrodes is provided to improve energy conversion rate and light efficiency by absorbing redundant electrons from an N electrode and converting the electrons into energy. CONSTITUTION: An N layer is formed on the front surface of a silicon single crystal wafer. A bus bar electrode(17) in which a finger electrode is grounded to the rear surface(11) of the silicon single crystal wafer is silk-printed. A ceramic insulation coating process is performed on the bus bar electrode and the finger electrode. A positive electrode is silk-printed on a positive electrode configuration space part. The positive electrode is chemically connected to a substrate of the positive electrode configuration space part.

Description

Solar cell have two emitter electrode

The present invention relates to a solar cell. The solar cell absorbs sunlight to get light energy, and becomes free electrons. It absorbs electrons and generates energy. It is provided through the diode, which is an important element, and is made of monocrystalline and polycrystalline silicon. There are thin-film solar cells made of bulk and amorphous, and solar cells using compounds include (GaAs, Inp) as crystalline form, (CdTe, CIGS) as thin film type, and (InGap / GaAs / Ge) as thin film laminate type. The most commonly used commercially available silicon crystals are used.

A silicon solar cell is a semiconductor device that converts light energy directly into electrical energy, and dissolves the purified silicon into a chamber to form an ingot, a single crystal mass, and cuts it thinly into wires to make a silicon wafer. Semiconductor wafers and silicon wafers for solar cells have a lot of difference in quality and shape of products because they are fundamentally different in usage, environment and process. Instead of using a lower quality in terms of quality than silicon wafers for semiconductors, they use very low cost silicon wafers.

The problem to be solved in the present invention is that the N-type diffusion layer is diffused not only in the light absorbing portion on the front surface of the silicon but also on the opposite side during the doping process of the single crystal silicon solar cell, so that the light absorbing surface and the back thereof have N electrodes. It is to make a solar cell having two N electrodes on one P electrode.

The problem to be solved by the present invention is that the N-type diffusion layer is diffused not only in the light absorbing portion but also the opposite side during the single crystal silicon solar cell doping process, naturally light absorbing portion is provided with the N electrode in the screen printing as in the prior art, Since the light absorption does not have to be kept in mind, the electrode of N and the electrode of P are distributed and provided.

The effect of the present invention is that the energy absorbed by the electrode of N of the light absorbing surface of the silicon wafer of the silicon single crystal and the electrons of N which are distributed like P on the back are absorbed and converted into energy. Solar cells with higher efficiency than batteries can be made.

FIG. 1 is a view showing wirings of a finger electrode 15 and a bus bar electrode 17 of the substrate front surface 10. FIG.
FIG. 2 is a view showing wirings of the finger electrode 15 and the bus bar electrode 17 on the substrate back 11; FIG.
FIG. 3 shows a finger electrode insulating means 34 and a bus bar electrode insulating means 36, which are insulating coating means covering the edges of the finger electrode 15 and the bus bar electrode 17 of the substrate back surface 11;
FIG. 4 is a view showing the edges of the finger electrodes 15 and the busbar electrodes 17 covered by screen printing in FIG. 2 with dotted lines.
FIG. 5 is a diagram illustrating a dotted line in FIG. 4; FIG.
Fig. 6 shows the plus electrode 40 to be screen printed.
FIG. 7 is a view showing the positive electrode 40 screen printed on the positive electrode composition space 28 provided between the finger electrode insulating means 34 of FIG.
8 is a view showing a substrate back 11 of the solar cell 100.

Hereinafter, the configuration and embodiments of the present invention will be described in detail with reference to the accompanying drawings. The substrate front surface 10 of FIG. 1, which is made of a single crystal silicon P-type substrate, removes defects and foreign substances generated during wafer cutting by SDR and surface texturing in a solar cell process, and partially etches tissue on the surface to reduce surface reflection loss. It is used to make fine pyramid structure as the most ideal structure by reducing light, confining light, increasing light absorption, causing diffuse reflection, and preventing incident light from being lost. The solar cell substrate may be a P-type substrate or an N-type substrate. However, the P-type substrate is generally used in a single crystal solar cell because the free electron flow is advantageous in all aspects of electricity. In the present invention, it is shown and described as a P-type substrate, it turns out that the N-type substrate can also be used. After the surface texturing process, doping process is carried out. In order to make P-type on N-type substrate, BBr3 is used as a substance containing group V of the Periodic Table of the Elements. When forming the N-type gas, usually POCl3, H3PO4, etc. containing Group V of the periodic table is used. An emitter of N can be made by placing a wafer in a quartz diffusion tuve inside a furnace at a suitable temperature, usually within 750 to 1000 degrees, and flowing a gas of POCI3. It diffuses from the entire surface, namely the front, the back, and the outer surface to form the emitter of N, and the depth of the doped emitter is usually used at 500 nm. Oxides, including phosphorous, formed during the N-type diffusion of the doping process on the silicon surface are removed by the PSG process. The anti-reflection coating ARC process is performed, which is a thin film formed to reduce the reflection loss of light on the surface of the solar cell. In order to prevent light absorption from the thin film itself, the band gap is large and the electrical insulation is excellent, and it is used as a material having strong characteristics against moisture and corrosion, and SiNx, SiO2 and TiO2 are used. Plasma-excited plasma enhanced dhemical vapor deposition) using PECVD. Then, metal printing is performed by screen printing on the entire silicon wafer. Metal printing is an electrode that absorbs light energy and collects converted electrical energy. In other words, a certain interval is spaced to absorb light on the front surface, the finger electrodes (fingers) are arranged, printed and dried with Ag paste, and then the busbar electrodes (busbars) are connected to each other. Light is absorbed between them. When the finger electrode 15 is printed on the substrate front surface 10 of FIG. 1 while maintaining a predetermined interval, the light absorbing space 18 is formed therebetween. The finger electrode 15 and the busbar electrode 17 are usually made of three kinds of metal pastes, and Ag, AgAl, Al, and the like are used. And the laser cut near the outer edge of the front side is doped on the side to separate the electrical coupling between the front and back. What has been described so far is the conventional solar cell universal technology. Wafer cleaning, surface organization, N-type diffusion, oxide film removal, anti-reflective coating, and front electrode printing are performed using the same technology as a conventional solar cell. As described above, the process of surface organization, N-type diffusion, oxide film removal, and anti-reflective coating is performed on the front, back, and side surfaces of the wafer without the use of a separate jig. It consists of organization, N-type diffusion, oxide removal and anti-reflection coating. This process serves as the most important advantage in the present invention. 1 illustrates a front surface of a conventional solar cell described above. The PN junction isolation is made by the above-described process, and the PN junction isolation is a laser beam placed at a predetermined distance from the front side of the wafer in order to electrically block the P-type electrode to be provided on the rear surface by the PN separation groove 19. Irradiate to a depth of about 20um to separate the PN. As shown in FIG. 2, in the present invention, the bus bar electrode 17 of the substrate front surface 10 is extended to the outermost surface and silk-printed, and the PN separation groove 19 also extends to the outer side of the bus bar electrode 17. Work to outer shell to separate PN. Hereinafter, the process of the substrate back surface 11 is demonstrated. First of all, conventional solar cells have an Al paste on the back to have a back field effect. In other words, Al-paste is screen printed on the back to make P-electrode, and firing is fixed for a suitable time at a suitable temperature within a temperature of about 600 to 950 degrees, and finger electrodes 15 and busbar electrodes 17 spread on the front side. It contacts N-type silicon and the rear P electrode diffuses inwards, and also has a P + -type electric field effect to push electrons, thereby improving efficiency of conventional solar cells. However, the present invention does not simply constitute a P-type electrode having an electric field effect on the rear surface, but also a bus bar electrode that collects N-type finger electrodes and finger electrodes to absorb energy converted into electricity of light energy of a long wavelength band on the rear surface. It is made by distributing the P-type electrode between them. When described in detail below, the configuration on the back of the conventional solar cell has a completely different process. The configuration and embodiment of the present invention will be described from the process at the substrate back 11 of FIG. Screen printing is performed on the substrate back 11 like the finger electrode 15 and the busbar electrode 17 on the substrate front surface 10 of FIG. 2, and the positive electrode composition space portion 28 provided therebetween is later added to the positive electrode. 40 is provided by silk printing, the cut is deeper than the depth formed than the depth of the N-type doped by the laser cutting in between to cut off electrically. That is, the finger electrode 15 and the bus bar electrode 17 are electrically cut off from the positive electrode component space portion 28 to form the positive electrode 40 by a laser cutting process. The laser cutting process and the silk printing process of each electrode may be reversed. In addition, in order to prevent the finger electrode 15, the bus bar electrode 17 and the positive electrode 40 from shorting, the finger electrode insulating means 34 and the bus bar electrode insulating means 36 as shown in FIG. The finger electrode 15 and the busbar electrode 17 are screen printed and insulated. As shown in FIG. 5, the finger electrodes 15 are all covered and insulated by the finger electrode insulating means 34, and the edges of the bus bar electrodes 17 are covered and insulated by the bus bar electrode insulating means 36. The coated finger electrode 15 and the bus bar electrode 17 are covered and coated, and the dotted line indicates the covered finger electrode 15 and the bus bar electrode 17. FIG. 6 is a view illustrating the deletion of the finger electrode 15 and the bus bar electrode 17, which are indicated by dotted lines in FIG. 5, and shows a positive electrode configuration space 28 formed between the finger electrode insulating means 34. As shown in FIG. 7, the positive electrode 40 is made of one electrode, and the positive electrode 40 is silk-printed in the positive electrode structure space 28 to cover the positive electrode 40. The electrode configuration space portion 28 is shown in FIG. 8 with a dotted line. As shown, screen printing with the positive electrode 40 on the finger electrode insulating means 34 and the positive electrode composition space portion 28 does not conduct to the finger electrode 15 by the finger electrode insulating means 34. All of the electrode component space portions 28 are connected to one, so that the electrode is configured as a positive electrode 40. Then, the bus bar electrode 17 and the positive electrode 40 are provided on the substrate rear surface 11, like the bus bar electrode 17, which is made in advance, and the positive electrode 40, the substrate front surface 10, and the substrate rear surface 11 are provided. The busbar electrode 17 made in Fig. 11 is used as a negative electrode. FIG. 9 is a rear view of the solar cell 100 shown by deleting the dotted lines in FIG. 8. The solar cell 100 thus produced is baked in a firing furnace at a temperature of about 600 to 900 degrees by firing for a suitable time, and each electrode diffuses toward the emitter to finish the process of becoming a contact. In the substrate front surface 10, when light is absorbed, light having a short wavelength is converted into electrical energy near the front surface and absorbed by the busbar electrode 17 and the positive electrode 40. 11 is absorbed by the side and converted into electrical energy is absorbed by the bus bar electrode 17 and the positive electrode 40 on the substrate back side 11 to increase the efficiency. As described above, the present invention includes the same finger electrode 15 and the bus bar electrode 17 on the front and rear surfaces of the substrate, so that the front end of the substrate at the end of the bus bar electrode 17, the N contact 45 10) The bus bar electrodes 17, which are the N-type electrodes on the substrate back 11, are contacted in parallel. An advantage of the present invention is that the N-type finger electrode 15 and the bus bar electrode 17 having the substrate front surface 10 are also provided on the substrate rear surface 11, so that the absorption of free electrons occurs very quickly and efficiently. As it moves, it reduces the rate of encounter with the hole and is absorbed by the electrode to increase the energy conversion rate.

Substrate Front (10) Substrate Back (11)
Finger electrode 15 Busbar electrode 17
Light absorption space part (18) PN separation groove (19)
Positive electrode composition space portion 28 Finger electrode insulation means 34
Bus bar electrode insulating means (36) plus electrode (40)
N-Contec (45) Solar Cell (100)

Claims

The silicon single crystal wafer is provided with N layers on its entire surface by a doping process, and silk-printed busbar electrodes on the front surface of the finger electrodes and the grounded electrodes in parallel, and laser-cut the outer edges of the substrate to form N-type and P-type substrates. In a silicon solar cell wafer that has been electrically blocked from an electrode, a finger electrode on the back and a busbar electrode having the finger electrode grounded in parallel are silk printed, dried, baked in a kiln and chemically contacted with N. In order to electrically block the outer edges of the finger electrode and busbar electrode and the positive electrode component space between them, the laser cutting cuts deeper than the depth of the N region and cuts it off electrically. Ceramic insulation coating and drying process on the bar electrode, baking in a kiln to stabilize ceramic insulation coating, and The positive electrode is silk-printed and dried in a baking furnace and chemically contacted with the substrate of the positive electrode component space in the firing furnace. Two emitter electrodes are provided with an N-type electrode and a P-type electrode on the back side. Solar cell provided with.

The area ratio of the area | region of the finger electrode and busbar electrode which are N electrodes, and the P-type electrode is the same, or the area of a P-type electrode is a little big, or the area of a P-type electrode is a little bit. A solar cell with two emitter electrodes of small size.

A solar cell having two emitter electrodes on the back of which a material of a finger electrode, a busbar electrode, or a P-type electrode is Ag, AgAl, Al, or a combination thereof or another metal paste.

The solar cell of claim 1, wherein a finger electrode, a bus bar electrode, and a P-type electrode are formed on a silicon wafer back side by depositing a metal material through a semiconductor deposition process.

2. The two emitter electrodes according to claim 1, wherein the process is performed in a reverse order in the finger electrode, the busbar electrode silk printing process, the insulation coating process of the electrode, or the process of laser cutting the outer shell thereof to electrically cut the electrode. Equipped solar cells.

The solar cell according to claim 1, wherein the wafer means is a silicon single crystal wafer, a silicon polycrystalline wafer, a silicon amorphous wafer, and two emitter electrodes of polysilicon grown by deposition means.

The solar cell according to claim 1, wherein the wafer means comprises two emitter electrodes comprising (GaAs, Inp) using a compound, (CdTe, CIGS), (InGap / GaAs / Ge), and the like.

N-type busbar electrodes provided on the front and rear surfaces of the substrate are provided with the same position and size on the front and rear surfaces, up to the outermost side of the substrate so that each N-type busbar electrode is in parallel contact at the outermost side. Solar cell with two emitter electrodes.