JPS6265478A - Photovoltaic device - Google Patents

Abstract

PURPOSE:To form semiconductor layers without using oxygen and suppress damages of P-type or N-type semiconductor layers caused by heat and high energy particles and oxidization of the respective semiconductor layers by employing nonoxide semiconductor layers instead of conventional oxide films in a photovoltaic device. CONSTITUTION:An incident light from a light transmitting insulating substrate 1 enters P-type, I-type and N-type amorphous semiconductor layers through a transparent electrode 2 and, while being absorbed, partially reaches an N-type amorphous semiconductor layer 6 which is a reflecting layer. As the light is scattered at the respective textured boundaries after being transmitted through the transparent electrode 2, only a little part of the incident light makes a right angle with the N-type amorphous semiconductor layer 6 which is the reflecting layer and most part of the incident light comes from the direction inclined to the reflecting layer. Therefore, together with the fact that the N-type amorphous semiconductor layer 6 has a low refractive index, total reflectance at the boundary is high and, moreover, the light transmitted through the semiconductor layer 6 is reflected by a silver backplane electrode 7 with a high reflectance and enters the N-type, I-type and P-type semiconductor layers 5, 4 and 3 again and is absorbed. With this constitution, confinement effect of the incident light can be increased and high photovoltaic characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photovoltaic device whose photovoltaic characteristics are improved by optical confinement.

[Prior art]

A conventional photovoltaic device of this type is constructed as shown in Vol.
2) ), FIG. 4 is a cross-sectional structural diagram of a conventional photovoltaic device, in which a transparent electrode 2, a p-type amorphous semiconductor layer 3, an i-type amorphous semiconductor layer 4 are formed on a transparent insulating substrate l. , n-type amorphous semiconductor layer 5, ITO (In203 +5n02) film 6'
, silver back electrode 7 are laminated in this order, and the light transmitted through the light-transmitting insulating substrate 1 and the transparent electrode 2 is transferred to p-type, i-type, and n-type amorphous semiconductor layers. 3, 4.5, and each of these p-type, i-type, and n-type amorphous semiconductors a
A part of the light transmitted through 3.4.5 is reflected by the film 6',
Further, the light transmitted through this film 6' is reflected by the back electrode 7 to confine the light, and is again introduced into each of the n-type, i-type, and p-type non-quality semiconductor layers 3, 4.5 to improve the photovoltaic properties. The generated photovoltaic force is taken out to the outside via the transparent electrode 2 and the back electrode 7.

(Problem to be solved by the invention) By the way, in the conventional device as mentioned above, it is p-type.

I-type and n-type semiconductor layers 3. 4. A film 6' formed using ITO or the like as a means of confining the light transmitted through 5.
is interposed between the n-type amorphous semiconductor layer 5 and the back electrode 7, but in a structure using a film 6' such as 1-0, this II! When 6' is formed on the n-type semiconductor N5, the n-type semiconductor layer is damaged by heat and high-energy particles, and since [116' is an oxide, oxygen is required during formation; There was a problem that oxidation of the n-type semiconductor layer 5 etc. due to oxygen was unavoidable.

Means for Solving Problem C] The present invention was made in view of the above circumstances, and its purpose is to form a semiconductor layer by using a non-oxide semiconductor layer in place of the conventional oxide film. In some cases, a photovoltaic device that eliminates the need for oxygen and effectively suppresses disadvantages such as p-plastic formation, damage to the n-type semiconductor layer due to heat and high-energy particles, and oxidation of each of these semiconductor layers. It is on offer.

The photovoltaic device according to the present invention has a refractive index smaller than that of the p-type or n-type semiconductor layer and a conductive layer between the p-type or n-type semiconductor layer and the back electrode laminated thereon. The present invention is characterized in that a non-oxide semiconductor layer whose properties are substantially the same as or higher than that of the p-type or n-type semiconductor layer is interposed.

【Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a cross-sectional structural diagram of a photovoltaic device according to the present invention (hereinafter referred to as the device of the present invention), in which 1 is a transparent insulating substrate made of glass or the like, 2 is a transparent electrode, and 3 is a transparent insulating substrate. A p-type amorphous semiconductor layer made of amorphous silicon carbide, 4 an n-type amorphous semiconductor layer made of silicon, 5 an n-type amorphous semiconductor layer made of silicon, and 6 a layer other than an oxide semiconductor. An n-type amorphous semiconductor layer is a semiconductor (hereinafter referred to as a non-oxide semiconductor), and 7 indicates a back electrode made of silver.

The device of the present invention has transparent electrodes 2, p on the transparent insulating substrate 1.
The n-type amorphous semiconductor layer 3, the n-type amorphous semiconductor layer 4, and the n-type amorphous semiconductor layer 5 are laminated in this order. An n-type amorphous semiconductor layer 6 whose refractive index is smaller than that of the n-type amorphous semiconductor layer 5 and whose conductivity is the same as or higher than that of the n-type amorphous semiconductor layer 5 is laminated thereon. It is constructed by laminating electrodes 7.

The surface of the transparent electrode 2 formed on the transparent insulating substrate l is first textured by forming irregularities of a required height by means such as etching. I-type and n-type amorphous semiconductors ii3, 4, 5
At each interface between the n-type amorphous semiconductor layer 6, which is a non-oxide semiconductor, and the back electrode 7, the unevenness gradually becomes shallower toward the upper layer, but a textured structure appears in each interface, scattering incident light. p-type, i-type, and n-type amorphous semiconductor layers 3°4
．． The length of the optical path within 5 is increased to increase the conversion efficiency for incident light.

The n-type amorphous semiconductor layer 6 is provided as a reflective layer for light transmitted through the p-type, i-type, and n-type amorphous semiconductor layers 3 and 4.5, and its refractive index is equal to that of the n-type amorphous semiconductor layer. 5 refractive index 3.
The conductivity is set to approximately 2.5 (less than 3.5 is sufficient), which is smaller than 5. Further, the film thickness is set to be 1400 thicker than that of the n-type amorphous semiconductor IW5, which is 400 thick. This makes them p-type and type 1.

n-type amorphous semiconductor layer 3. 4. The reflectance of light passing through the filter 5 is increased, and the extraction of photovoltaic force is not affected in any way. The conductivity of the n-type amorphous semiconductor layer 6 is set according to the conductivity of the n-type amorphous semiconductor layer 5, but the conductivity of the n-type crystalline semiconductor Ff5 is 10Ω.
Since it is sometimes set as low as -10-1, n
The conductivity of the entire amorphous semiconductor Ff6 may also be 10-5Ω=aa' or more.

Note that as the material of the n-type amorphous semiconductor layer 6 provided as this reflective layer, in addition to amorphous silicon nitride, amorphous silicon nitride or the like may be used. Table 1 shows an example of the thickness and refractive index of each of the p-type, i-type, and n-type amorphous semiconductor layers, and the n-type amorphous semiconductor layer 6 which is a non-oxide semiconductor serving as a reflective layer. .

Table 1 In the device of the present invention as described above, the light-transmitting insulating substrate l
The incident light passes through the transparent electrode 2 and becomes p-type.

The light enters the i-type and n-type amorphous semiconductor layers, is absorbed, and a portion reaches the n-type amorphous semiconductor layer 6, which is a reflective layer. After light passes through the transparent electrode 2, it is scattered at each textured interface, so very little light enters the n-type amorphous semiconductor layer 6, which is a reflective layer, at right angles, and most of the light enters obliquely. Therefore, together with the low refractive index of the n-type crystalline semiconductor rrI6, the total reflectance at the interface is high, and furthermore, the light transmitted through the n-type amorphous semiconductor layer 6, which is this reflectance, has a low reflectance. The reflected light is reflected by the high silver back electrode 7, and the reflected light is reflected again into each of the n-type, i-type, and p-type amorphous semiconductor layers 5, 4, .
3 and is absorbed, the effect of confining the incident light is large, and high photovoltaic properties are obtained.

Figure 2 shows the spectrum of light incident perpendicularly to the earth on the device of the present invention and the conventional device.
2 is a graph showing the results of investigating the characteristics 1 and 2 when irradiated with 2 irradiations, with the horizontal axis representing the open circuit voltage (V) and the vertical axis representing the short circuit current density (mA/cs2). The solid line in the graph shows the results of the device of the present invention, and the broken line shows the results of the conventional device. As is clear from this graph, the open circuit voltage,
It can be seen that the device of the present invention is superior in terms of short circuit current density.
Table 2 shows an example of specific numerical values for both.

(Margin below) Table 2 FIG. 3 is a cross-sectional structural diagram showing another embodiment of the present invention,
In this embodiment, among the p-type, i-type, and n-type amorphous semiconductor layers, the n-type amorphous semiconductor 8 itself located adjacent to the back electrode 7 is a non-oxide semiconductor. It is made of crystalline silicon carbide, and its refractive index is set to approximately 2.5, which is smaller than the refractive index of the original n-type amorphous semiconductor layer, which is 3.5, and its conductivity is also the same as that of the original n-type semiconductor layer. The conductivity of the amorphous semiconductor layer is set to a value equal to or higher than 10-3 Ωcm-1, and the film thickness is thicker than the original thickness of the n-type amorphous semiconductor layer. The number is set at 1,400 people.

The other configurations are substantially the same as the embodiment shown in FIG. 1,
Corresponding parts are given the same numbers and explanations are omitted.

In such a device of the present invention, the n-type amorphous semiconductor layer 8
Since it functions as a reflective layer as it is, there is no need to form a special reflective layer, the absorption loss is correspondingly small, and the manufacturing process is also simplified.

In each of the above embodiments, a p-type electrode is formed on the transparent electrode 2.

Although we have described a structure in which i-type and n-type amorphous semiconductor layers 3.4.5 are laminated in this order and light is introduced from the p-type amorphous semiconductor layer 3 side, the n-type , i-type, and p-type amorphous semiconductor layers are stacked in this order. In this case, between the p-type crystalline semiconductor layer and the back electrode, A p-type crystalline semiconductor layer, which is a non-oxide semiconductor layer whose refractive index is smaller than that of the p-type crystalline semiconductor layer and whose conductivity is the same or higher, may be interposed.

In addition, the p-type amorphous semiconductor layer itself adjacent to the back electrode is made of a non-oxide semiconductor, which has a refractive index smaller than that of the original p-type crystalline semiconductor layer and has the same or higher conductivity. It may be configured as an amorphous semiconductor layer and provided with a reflective function.

Furthermore, although the above embodiments have all been described with respect to a p-1-n junction type photovoltaic device, it goes without saying that they can also be applied to a p-n junction type.

Furthermore, although each of the above explanations is based on the case where each semiconductor layer is made of an amorphous semiconductor, the present invention is not limited to this in any way, and may be made of a single crystal semiconductor, a microcrystalline semiconductor, or an appropriate combination of these. There may be.

〔effect〕

As described above, in the device of the present invention, between the back electrode and the adjacent p-type or n-type semiconductor layer, or between the back electrode and the adjacent p-type or n-type semiconductor layer itself, the refractive index is p-type. Since it is made of a non-oxide semiconductor that is smaller than an n-type semiconductor and has a conductivity that is equal to or higher than this, the reflectance for light that has passed through the p-type and n-type semiconductor layers is significantly improved.
Effective use of incident light can be achieved and conversion efficiency can be greatly improved,
Moreover, the material of this non-oxide semiconductor is p-type.

If it is the same as that of the n-type semiconductor layer, the equipment itself will be p-type and n-type.
The present invention has excellent effects, such as the fact that the equipment used for forming semiconductor layers can be used as is, and the equipment cost can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of the device of the present invention, FIG. 2 is a graph showing comparative test results between the device of the present invention and a conventional device, FIG. 3 is a cross-sectional structural diagram showing another embodiment of the present invention, and FIG. The figure is a cross-sectional structural diagram of a conventional device. 1... Transparent insulating substrate 2... Transparent electrode 3...
P-type amorphous semiconductor layer 4...I-type amorphous semiconductor layer 5...
... n-type amorphous semiconductor layer 6 ... non-oxide semiconductor layer 7 ... back electrode 8 ... n-type oxide semiconductor layer
Applicant Sanyo Electric Co., Ltd. Agent Patent Attorney Norio Kono

Claims (1)

[Claims] 1. A material having a refractive index lower than that of the p-type or n-type semiconductor layer and having a conductivity between the p-type or n-type semiconductor layer and the back electrode laminated thereon. A photovoltaic device characterized in that a non-oxide semiconductor layer having a thickness substantially the same as or higher than that of the p-type or n-type semiconductor layer is interposed. 2. The electromotive force device according to claim 1, wherein at least one semiconductor layer including the p-type or n-type semiconductor layer is an amorphous semiconductor layer. 3. The p-type or n-type semiconductor layer laminated with the back electrode has a refractive index of less than 3.5 and a conductivity of 10^-^5.
1. A photovoltaic device comprising a non-oxide semiconductor having a resistance equal to or higher than Ω^-^1 cm^-^1. 4. The photovoltaic device according to claim 3, wherein at least one semiconductor layer including the p-type or n-type semiconductor layer is an amorphous semiconductor.