JPS6035553A - Thin film solar cell device - Google Patents

Abstract

PURPOSE:To obtain the titled device enabling the effective electrical connection among solar cell elements by forming plural electrodes, thin film solar cell element layers and back electrodes on an insulating substrate with the specified arrangement. CONSTITUTION:Plural electrodes 2 are formed on an insulating substrate 1 in the specified intervals and plural thin film solar cell element layers 4 are deposited to cover the electrodes 2 with leaving a part of each electrode 2. Further, back electrodes 6 are arranged on each region of the thin film solar cell element layers 4, the extended ends of which reach the exposed parts of the substrate electrodes 2 of the adjacent thin film solar cell element layers 4, thereby connecting the plural thin film solar cell elements in series. For example, on a light-transmitting glass substrate 1, electrodes 2 formed by printing with a paste of silver group, ITO transparent electrodes 3, amorphous Si thin films 4 and Ni back electrodes 6 formed by electroless plating and electrolytic plating are formed with the above described arrangement and the amorphous Si elements are connected electrically in series.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a thin film solar cell device in an amorphous form, and particularly relates to a thin film solar cell device in which a plurality of elements are electrically connected on the same substrate. .

<Prior art> In order to effectively utilize solar energy, there is an urgent need to develop high-efficiency, low-cost power solar cells. Attempts are being made to reduce the element manufacturing process cost by increasing the area.

However, when the area of a single element is increased, an extremely large current flows as an output, and unless the resistance of the element electrodes is reduced accordingly, the power loss due to the electrode resistance becomes large and cannot be ignored. On the other hand, if the electrode 41 charge is constant, the ionization area will increase in order to prevent power loss, which will reduce the effective efficiency of the device. Therefore, in conventional solar cells, a method is adopted in which all electrodes are led out from 2 to 8 locations around the wafer and interconnected. However, this causes the cost of connection wiring between elements to become extremely high. Divide into a large number of single rectangular solar cell elements,
If they are electrically connected in series in the long side direction, the output voltage increases proportionally, and the output current can be relatively reduced. Therefore, the conditions for electrode resistance are relaxed.

When constructing a solar cell panel by connecting n solar cell elements, a circuit in which each element is connected in parallel as shown in Figure 1 (a) and a circuit in series as shown in Figure 1 (1)) Power loss due to resistance r of each element W a + l'l' 5
Looking at the total ratio, it becomes ~'Vb-nlr, and in the solar panel structure, series connection can reduce power loss, and as it is clear from the above equation, as the number of elements increases, the difference between the two becomes becomes noticeable.

Although the series connection method is superior in terms of power loss as mentioned above, it is not actively used in conventional silicon crystal solar cells because the manufacturing process costs are reduced by reducing the wafer size. This is mostly due to disadvantages such as high cost and high assembly and wiring costs.

Purpose of the Invention: Kinoi '5J replaces the above-mentioned silicon single crystal solar cell.
The device is constructed using Amorphous thin film solar cell elements that can be easily divided into elements, and an increase in the number of elements does not lead to an increase in manufacturing process and wiring assembly costs. Provides a battery device.

<Example> An example using amorphous silicon t as a thin film semiconductor will be described. In FIGS. 2 and 3, reference numeral 1 denotes a translucent glass substrate that constitutes the entire light-receiving surface of the solar cell device, and the surface of the glass substrate I is pattern-printed with silver thread electrode bursts by the lux screen method. , followed by firing and printing onto the glass substrate surface. The electrode 2 is formed of a part of a bus bar for internal connection on the light receiving surface and a grid electrode commonly connected by the part of the bus bar. The film thickness of electrode 2 is 7 to 2071 m, and the sorting resistance is approximately ax+o''ΩA]
, and rlJf01~O, 15m of the crid electrode.
+11. Assuming a total gap of 33 mm and a QT-element of 25 gates, the electrode resistance on the lid side is about 15 x 10 Ω/], and the ratio of the electrode area of the lid part to the light receiving surface is 3 to 4%, which is historically If you add Hasha/Part, it becomes 9-11%.

Next, ITO (a mixture of indium oxide and tin oxide) transparent electrode material is evaporated to a thickness of 1000 to 1500 mm over the entire surface of the glass substrate using an electronic beam evaporation apparatus, covering the electrode 2 of the glass substrate. The transparent IJIJ electrode material is covered with an acid-resistant mask in a desired pattern and pattern-etched with an acidic solution to form an ITO transparent electrode 3. The refractive index of the ITO film 3 in the visible range is 19-2.0, the refractive index of the H-5 substrate 1 is 14-15, and the refractive index of the Amorph 7 silicon is 3.
0 to 35, but it takes a value intermediate between the two, and has the effect of preventing incident light from being reflected at the interface. An amorphous silicon thin film 4 is formed on a glass substrate on which electrodes are formed. The silicon thin film 4 is grown using a gas mixture of hydrogen caspase and 10% monosilane as raw material, and grown over the electrode 2 and transparent electrode 3 using a diode-type low-pressure glow discharge device, or grown using the mixed gas described above. Add a small amount of phosphine gas (PH3/H2) to
A doped 500-1000λ thick (7) n+ amorphous silicon film is grown to the full film length, then a 4000-2000 OA thick undoped amorphous silicon film is deposited using only a mixed gas, and then diborane gas (B2 /H2) Add a small amount of gas to 80-5
A p-type amorphous silicon film with a thickness of 00λ is grown.

That is, a solar cell element layer having an n-n-p structure is obtained.

The silicon thin film 4 is covered with a mask in a desired pattern using the conventionally known 4-IJ photolithography technique, and is divided into, for example, four individual devices by dry etching using plasma, corresponding to the electrode patterns. The edge side surface of each divided silicon thin film 4 is covered with a 1000-3000λ thick nitride film 5 synthesized from a mixed gas of SiH4/H2°NH4 and N2 by a glow discharge method. A nickel back electrode 6 is formed using both electroless plating and electrolytic plating on the exposed silicon thin film surface covered with the nitride film 5, and the amorphous silicon elements are electrically connected in series. The back electrode 6 is +07
At a thickness of about 7 m, the resistance of one sort can be reduced to an extremely low value of 7XIOΩ/Ω.

Silicon thin film 4゜4・divided on the same substrate 1
- As is clear from the figure, the electrical connection between the back electrode 6 formed to cover the entirety of each silicon thin film 4 is connected to the helical part of the electrode 2 connected to the adjacent silicon thin film 4 on the substrate 1. This is done by reaching . In this connection structure, since electrical connections are made between adjacent elements on the long sides of each divided silicon rJ film 4, the resistance value can be substantially reduced.

Next, over the silicon elements connected in series, the entire area on the glass substrate (excluding the Ag-based fired electrode pad part 2' for external wiring) was subjected to glow discharge, low-pressure CVD, ion blating, and spantal link film. It is formed to be thick or shaped using an organic material.

As described above, after the external connection lead wires 8 are attached to the solar cell glass substrate on which the panvation film 7 is formed using an inorganic or organic material, more reliable mechanical protection is applied to the back side. In order to achieve this, a glass plate IO serving as a back support plate is placed over the entire back surface of the substrate via a relatively soft silicone resin layer 9f, and the periphery is sealed to seal it from the outside.

In addition, when constructing a solar cell device with a large panel area, as shown in Figs. 4 and 5, amorphous silicon elements are connected in parallel to each other in order to obtain the desired output. voltage can be obtained.

ITO, which is used in solar cell devices, is extremely expensive to reduce the sorting resistance of back electrodes, etc. below a certain value, whereas fired electrodes and metal thin film electrodes for current collection and external leads are used. can be obtained relatively easily and at low cost with low sorting resistance, there is almost no inconvenience caused by dividing the elements, and it is possible to easily connect the elements in series. The points obtained can be effectively utilized.

Effects> As described above, according to the present invention, by selecting the electrode positions that connect thin film solar cell elements, output can be efficiently extracted, and a highly efficient solar cell can be obtained by reducing power loss due to electrode resistance. I can do it.

[Brief explanation of the drawing]

1(a) and (b) are equivalent circuit diagrams of solar cell elements connected in parallel and series, FIG. 2 is an exploded view showing an embodiment according to the present invention, and FIG. 3 is a sectional view of the same embodiment. FIG. 4 is a perspective view of another embodiment of the present invention, and FIG. 5 is an equivalent circuit diagram of the same embodiment. 1° glass substrate, 2: electrode, 3: transparent electrode, 4: amorphous silicon element 16: back type Th, 7 vacillation film, 9: silicone resin,] O: back glass plate. Agent Patent attorney Aihiko Fukushi (2 others) (Q) (b) Figure 1 0 Figure 3 and Figure 2

Claims (1)

[Claims] 1) a plurality of electrodes formed at predetermined intervals on an insulating substrate;
A plurality of thin film solar cell element layers deposited covering each electrode, leaving a part of each electrode, and a thin film solar cell element layer formed on each region of the thin film solar cell element layer and having extended ends close to each other. A thin film solar cell device f;t characterized by comprising a back electrode reaching the exposed portion of the substrate electrode, and comprising a plurality of thin film solar cell elements connected in series. 2) The connecting portion between the substrate electrode and the back electrode that electrically connects the adjacent thin film solar cell element layers is located in the long side direction of the thin film solar cell element shape. thin film solar cell device. 3) The side wall of each thin-film solar cell covered by the extension of the back electrode is coated with an insulating thin film in advance.) The insulating substrate is translucent. It consists of a substrate, and the substrate electrode consists of a transparent electrode (!:
The thin film solar cell device according to claim 1, 2, or 3, characterized in that it has all the characteristics. 5) The substrate electrode is comprised of a grid electrode for current collection, a pass bar that connects all the grid electrodes, and a transparent J electrode that covers the grid electrode part. The thin film solar cell device according to item 2, item 3 or item 4. 6) The thin film solar cell device according to item 5, wherein a portion of the bus bar serves as an electrical connection portion with a back electrode.