JPS6114769A - Photovoltaic device - Google Patents

Abstract

PURPOSE:To divide electric extension of the second electrode film coated on a photoactive layer at every photoelectric conversion region without thermal damage to the first electrode film by coating the exposed boundary from the photoactive layer of the first electrode film with an insulating heat adibatic layer. CONSTITUTION:An insulating heat adiabatic layer 8 for coating exposed boundaries 2a'', 2b'', 2c'',... are formed from the left side edges of photoactive layers 3a, 3b, 3c,... in the exposed ports 2a', 2b', 2c',... of transparent electrode films 2a, 2b, 2c,.... The layer 8 operates as a heat adiabatic layer when a back surface electrode film 4 of the second electrode film is divided at every photoelectric conversion regions 5a, 5b, 5c,... are emitted with a laser beam. Since the layer 8 of SiO2 is inserted to the boundary between the film 4 of aluminum and the film 2 of the SiO2 or the boundary between a photoactive layer 3 of a-Si and the film 2 of SnO2, the surface temperature of the film 2 becomes room temperature, thereby providing very large heat adiabatic operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a photovoltaic device that generates electromotive force by irradiation with light.

←) Prior art Figure 1 shows the basic structure of a photovoltaic device that is disclosed in U.S. Pat. No. 4,281,208 and has already been put into practical use. A substrate having optical properties, (21 (2b) (20)...
・8n02, I dividedly arranged on the surface of the substrate (1)
A transparent electrode film made of a transparent oxide conductor such as TO controls the first electrode film. (6B) (3b) (3o), . . . are amorphous silicon, amorphous silicon carbide, amorphous silicon deposited on the transparent electrode film (2B) (2b) (20)... Photoactive layer of film-like amorphous semiconductor containing germanium and microcrystals thereof, (4m) (4b) (4o)
・- is the photoactive #(3a)(3b)(5G)...
A back WL electrode film made of an ohmic metal that controls a second electrode film superimposed on the back electrode film (4a) (4b);
)(40)... each of adjacent photoactive 1i1(3a
)(5b)(30)・2>=ra11 exit, l! Exposed portions (2b') (20') of Meiden electrode film 2b) (20)...
One photoactive N(3&) extending directly toward...
(3b) (3c)... and its photoactive Ml (5a) (
Transparent electrode films (2a) (2b) sandwiching 3b) (3o), .
) (2C) and back electrode film (4111) (4b) (40
)... A plurality of light weight conversion regions (5a) (5b
)(50)... are electrically connected in series.

The above-mentioned photoactive materials 1 (3a) (3b) (30), etc. contain semiconductor junctions such as, for example, PIN junctions parallel to the film surface, or multiple structures thereof, so-called tandem structures, and therefore, the substrate (1) and Transparent %I electrode film 2a) (2b) (20)・
...When light is irradiated sequentially, an electromotive force is generated, and the electromotive force is added at once and taken out.

In a photovoltaic device with a normal configuration, l1llIv
! ! Photo-etching technology, which has excellent processability, is used. In the case of this technique, the process of depositing a transparent electrode film on the entire surface of the substrate (1), and the separation of each individual transparent electrode film (21 (2b) (20)...) by photoresist and etching. Transparent electrode Jll (2B) (2b) (20)
. . . . . . . . . . . . . . . . . . . . . ) . . . . fIJ (3B) (3b) (3c) . . . are separated, that is, the adjacent spaced portions of each photoactive layer (3a) (3b) (31 . . .) are removed in sequence.

However, although photo-etching technology is excellent in terms of fine processing, it tends to cause defects in the amorphous semiconductor film due to pinholes or peeling at the periphery of the photoresist that defines the etching pattern.

The prior art disclosed in Japanese Patent Application Laid-Open No. 57-1257!18 provides the above-mentioned adjacent spacing by burning out the film by laser beam irradiation, and does not require any photoresist, that is, a wet process, which is necessary for photolithography. This technique, which allows for fine processing without the use of metal, is extremely effective in solving the above-mentioned problems.

The first thing to keep in mind when using a laser is that such laser processing is essentially thermal processing, and if there is another film under the film to be processed, it may be damaged. It's about not giving. Otherwise, not only the desired film portion but also the unnecessary lower film may be burned off, or thermal damage may occur even if the film is not burnt out.

The above-mentioned prior art proposes selecting the laser power and pulse frequency for each layer in order to meet this requirement.

However, the back electrode films (4a) (4b) (4) formed on the N3 layer of photoactive 1 (3a) (3b) (30)...
C)... is selected from well-known ohmic metals such as aluminum, titanium, gold, silver, etc. in order to make ohmic contact with the N-type layer, and among them, aluminum is particularly effective in preventing light from passing through the N-type layer. Type I (which again contributes to optical wL conversion)
Although it is an advantageous material because it can reflect light on the non-doped (non-doped) layer and is inexpensive, on the other hand, as mentioned above, the patterning process by laser beam irradiation depends on the type of laser used. However, the reflectance for general laser beams is high, for example, at a wavelength of 1.06μ.
In the YAG laser of m, the lower layer transparent electrode film (2B) (2b) (
20)-17) III exit part (2a') (21)')
(2G')... is difficult to process without causing thermal damage. JP-A-57-12568, which discloses the laser patterning described above, also discloses that the back surface [in the embodiments using aluminum as the electrode material, the photoactive layer which has already been laser patterned with such aluminum ( 6&) (3b) (30)... and transparent conductive film (2
A method is adopted in which vapor deposition is performed obliquely to a), (2b), (20), etc., and a pattern is directly formed without laser processing.

Furthermore, the second thing to keep in mind when carrying out p-thermal processing by laser beam irradiation is that when laser processing the back electrode film (4b)... as shown in FIG. 4b)・
Since it is made of ohmic metal, it generally has good thermal conductivity, and the back electrode film edge (7) of the adjacent gap part (6) to be removed.
When ... hangs down due to melting, the transparent electrode J [(2b) ... of the photoelectric conversion region (5b) ... is below it.
Since the exposed part (2b')... of the transparent v
One light weight conversion region (5b) in contact with the l-pole film (2b)
)... is t! [This is to short-circuit.]

(c) Purpose of the Invention The present invention has been made in view of the above points, and its purpose is to avoid thermal damage to the lower layers and to avoid short-circuit accidents. The object of the present invention is to provide a photovoltaic device in which the overlapping extension of the back N-pole film that controls the 211r polar film can be divided by irradiation with an energy beam such as a laser beam.

B) Structure of the Invention The photovoltaic device of the present invention comprises a substrate having an insulating surface, a first t1' polar film dividedly arranged on the insulating surface of the substrate, and a part thereof exposed on the first W polar film. an fc second electrode film divided and arranged on the photoactive layer; and an exposed portion of the first electrode film extending from the second electrode film and exposed from the adjacent photoactive layer. the electrically connected schematic extension of the second N electrode film; an insulating heat-insulating layer covering the exposed interface exposed from the photoactive layer in the exposed part of the first electrode film; 2. The N-shaped extension of the polar film is deposited on at least the first photoactive layer in instantaneous contact across the exposed portion of the polar film and the insulating and heat-insulating layer, and then an energy beam is applied onto the insulating and heat-insulating layer. The structure is such that it is removed and divided by irradiation.

(E) Embodiment FIG. 6 shows an embodiment of the photovoltaic device of the present invention. Components that are the same as the conventional device shown in FIG. That is, the structural feature of the present invention is that the transparent electrode film (21 (2b) (20) - (D exposed part (2a')
2b') (2o')-c for each photoactive layer (3B) (
3b) (30)...Exposed interface from the left edge of (2a) (
2b") (2C")...
1f8++8)... is provided, and such an insulating and heat-insulating layer (8
1+81 (81... means that the back monopolar film which is the second electrode film is each photoactive layer (3B) (31) ) (30) ・
..., jll exit part (2a') (2b') (20')
After coating the back electrode film over the entire surface of the photoelectric conversion area (5 (81 + 81...),
B)(5b)(50)... It acts as a heat insulating layer during irradiation with the laser beam to be divided.

FIG. 4 shows the laser beam (L) irradiation process after the back electrode film (4) is deposited on the negative side.

In the figure, (9) is an objective lens for adjusting the beam diameter of the laser beam (L), and the laser beam (L) focused by the objective lens (9) is directed to an irradiation area A defined by a dashed line. It is scanned to irradiate B. Such figures 4 and 5
Laser beam (L) is
The insulation and heat insulation layer +81 (81+81...
Explain the insulation effect of

The specific material of the back electrode film (4) to which the laser beam (L) is irradiated is aluminum <
kl), amorphous silicon (a-8i), silicon dioxide (8i02), tin oxide (Sn02), and glass, and except for the glass, which is the material of the substrate (1), the other film thicknesses were uniformly 5000A. . Also, as a laser, the wavelength is 1.06
A Q-switched YAG laser with a pulse width of 100 nm and a pulse width of 100 nm was used. Incidentally, the reflectance of AI with respect to such a YAG laser is about 92%, and the All! The output IO of the laser beam was controlled so that the temperature of the exit surface uniformly reached 933°, which is the melting point of the Al. That is, FIGS. 5 and 6 show the temperature distribution in the irradiation area A, where FIG. 5 shows the temperature distribution using the device of the present invention, and FIG.
iIi (This is a conventional device in which 8J does not exist. 1fC1 Figures 7 and 8 show the temperature distribution in the irradiation area B,
FIG. 7 shows the device of the present invention, and FIG. 8 shows the conventional device.

As is clear from such temperature distribution, the insulation and insulation m of 8102
(El is attached to the back side of A/, the interface between the polar film (4) and 5n02 (D transparent vL polar film (2b), or the photoactive I of a-8i.
In the device of the present invention disposed at the interface between m (3b) and 8n02 (7) transparent tffl film (2b), the transparency %,
The surface temperature of the polar membrane (2b) is 296 degrees to the room temperature, and has an extremely large heat insulating effect! do.

On the other hand, as shown in FIGS. 5 to 8, the laser beam output IO that should uniformly raise the temperature of the exit surface of i
Since heat conduction to the 11 electrode film (2b) is blocked, the device of the present invention requires lower output. In other words, the fact that the laser beam output IO that should rise to the same temperature can be achieved with a low output means that
This means that a desired pattern can be processed using a low-power laser.

In addition to 8102, the above-mentioned insulation and heat insulation layer (8)... is 8iaN
4, A120a, P8(], B5Cl, etc., and thermal oxidation (nitridation), various OVD methods, and sputtering methods well known to those skilled in the art are used, but in particular, 8i02 and 8iaN+ are laser 0VI) method, i.e. silane (8iH4) and oxygen (
02) Alternatively, a raw material gas exclusively for nitrogen (N2), ammonia (NH3), and nitrous oxide (N20) is introduced into the Nayampa, and the medical director applies ultraviolet light only to the areas where the insulation and heat insulation layer (8)... is to be formed. Irradiation with an excimer laser beam having a wavelength of, for example, 193 nm is preferable because the raw material gas is thermally excited and the 8i02 or 8i3N4 film is directly patterned at that location. Furthermore, the laser OVD method itself is A.
ppCPPhys, Lett, 40(8), pp. 716-718 [La5er-induced ohemi
oalvapor position of
8i02JPJJ1oyer et al., and is well known.

In addition, another suitable forming method other than the laser OVD method is the plasma OVD method, in which the raw material gas is introduced into the glow discharge device, and the areas where it would be inconvenient to deposit the substrate ( 1) is placed in the above-mentioned discharge device and a glow discharge is excited. Also by this method, the source gas is plasma decomposed and the 8102 or 8iaN4 film can be easily formed selectively through a mask.

Insulating and heat-insulating layers such as 8102.8i3N4 (81.
Prior to the formation of U photoactive layers (3a) (3b) (30) and l), M bright electrodes (2a) (2b) (20
)... is performed after dividing and forming. Insulating heat insulation layer (81 (
8) (8i... When the formation is completed, the transparent wI electrode film 2B) (2b, ) (20)... and the insulating and heat-insulating layer (81
+81 (81-...A photoactive layer with at least one semiconductor junction is formed on the entire upper surface, and the photoactive layer is irradiated with a laser beam to form a transparent To electrode film 2a) (2b) (2
゜)... exposed parts (2a') (2b') (20'
) and the above-mentioned insulation and heat insulation N (8) h (8)... are exposed from their adjacent interfaces, and each photoelectric conversion region (5a)
(5b) (5C)... are individually divided. Then, the photoactive layer 1a) (3b) (30)..., the insulating heat-insulating layer +81 (81(8j...) and the transparent electrode film (2a)(
2b) Exposed part (2a') (2b') of (20)...
(20')...A back electrode film (4) is deposited on the entire upper surface. Figure 4 shows the laser removal process of the evaporated 6% polar film (4) and the irradiated areas A, H as described above.
The transparent electrode film (2&) (2b) (20)... is provided with an insulating and heat-insulating layer +8) f81 (81...) on top, and has a heat-insulating effect against the irradiation of the laser beam. Therefore, even if Ag or A1 alloy, which has poor selective machinability with a laser beam, is used as the back surface frost polarization (4), the above insulation and heat insulation PImf&(8)t8+・
Transparent polar films (2a) (2b) covered with...
2c)... is subjected to buttering processing without receiving thermal damage. In addition, even when using other ohmic metals, a considerably large laser output condition is allowed, and as a result, the processing conditions are relaxed and selective processing becomes easy despite t'Ifc.

FIG. 9 shows the state of the back electrode film (4) after laser patterning. Upper rudder insulation insulation N (8i f81
(81... Idv - It acted as a heat insulator to prevent thermal damage to the underlying layer during laser beam irradiation, but after laser beam irradiation, that is, after buttering, it acted as an insulator to prevent damage.) are doing.

FIG. 10 shows another embodiment of the photovoltaic device of the present invention, and the difference from the previous embodiment is that the adjacent photoelectric conversion regions (5a) (
5b)... in series connection form. That is, in this embodiment, the back electrode film (4a) controlling the second electrode film...
The exposed portion (2b') of the transparent electrode film 2b) is exposed in the photoelectric conversion region (5b) directly adjacent to the right.
Rather than being combined with..., the back surface T& film (4a)... and the transparent electrode film (2b)... are indirectly coupled by the three-layered connection if electrode film 0)... Therefore, the connection electrode film QOI... is the back electrode film (4B)
It acts as a mechanical extension of... Above connection-
° The three-layer structure of polar film (101) is divided into transparent electrode film (2
b) ... From the side, titanium (Ti) or titanium silver (T
iAg), Al or FiA1 alloy, and Ti or Ti
Ti or TiAg in the lower layer (101)
is A, which is essential for reducing the sheet resistance of intermediate NII (102).
j7 is a translucent conductive oxide (T
High-resistance Al2O formed at the interface when directly combined with the transparent electrode film (2b) consisting of CO)
This is to prevent oxidation, which results in 3.
Ti or TiAg (103) is a moisture-resistant film of Al or A1 alloy which is the intermediate layer (102).

In addition, the surface electrode film (4a) in such a configuration is made of Al.
Or A1 alloy, such back electrode film (4a)...
When the transparent electrode film (2b) is buttered by laser beam irradiation as in the previous example, the exposed portion (2b) of the transparent electrode film (2b)...
')... will be exposed by laser beam irradiation, so it is formed by selective vapor deposition with unnecessary parts covered with a mask. Back N electrode film (4a) produced by such selective vapor deposition method...
In order to reduce the series resistance, the exposed length of the transparent electrode film (21) must be a certain length or more, and the connection N electrode film 00 to be deposited next. )...
Since the pattern is patterned by irradiation with the laser beam (L) as shown in FIG. 11, it does not substantially impede the reduction in the distance between the adjacent spaced portions.

(F) Effects of the Invention As is clear from the above description, the photovoltaic device of the present invention has a heat insulating layer that insulates the exposed interface from the photoactive layer in the first electrode film 1 which is dividedly arranged on the insulating surface of the substrate. The second electrode film was deposited on the adjacent photoactive layer beyond the exposed portion of the 11th electrode film and the insulating and heat-insulating layer. The optical extension part is irradiated with an energy beam on the insulating and heat-insulating layer without causing thermal damage to the underlying MS1 electrode film, and without causing a short circuit in the photoelectric interlayer region. It can be divided into each photoelectric conversion area.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional photovoltaic device, FIG. 2 is an enlarged cross-sectional view explaining the drawbacks of the conventional device, FIG. 6 is a cross-sectional view of an embodiment of the photovoltaic device of the present invention, and FIG. 5 and 7 are curve diagrams illustrating the temperature gradient in the present invention, and FIGS. 6 and 8 are diagrams illustrating the manufacturing process in the present invention. A curve diagram explaining the temperature gradient, FIG. 9 is an enlarged cross-sectional view of one embodiment of the present invention, FIG. 10 is an enlarged cross-sectional view of another embodiment of the photovoltaic device of the present invention, and FIG. 11 is such an embodiment. FIG. (1)...Substrate, (2m>(2b)<20)=
・-・Transparent wL electrode film (3a) (3b) (30)・-・
... Photoactive layer, (4 & ) (4b) (40)
...-J (surface t1kg, (8)...Insulating heat insulation layer, αα...Connection electrode film.

Claims (1)

[Claims] (1) A substrate having an insulating surface, a first electrode film dividedly arranged on the insulating surface of the substrate, a photoactive layer dividedly arranged on the first electrode film with a part thereof exposed; A second electrode film dividedly arranged on the photoactive layer, and an electrical connection between the second electrode film and the exposed portion of the first electrode film extending from the second electrode film and exposed from the adjacent photoactive layer. an insulating and heat-insulating layer covering an exposed interface exposed from the photoactive layer in the exposed portion of the first electrode film, the electrically extending portion of the second electrode film being connected to at least the first electrode. The photoactive material is deposited on the adjacent photoactive layer across the exposed portion of the film and the insulating and heat-insulating layer, and then removed and divided by irradiation with an energy beam on the insulating and heat-insulating layer. Power equipment.