JPH07335928A - Photovoltaic element - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the photovoltaic characteristics by making the short-circuit current value of the photovoltaic diodes uniform to a high value by making the amount of light received by the central and peripheral photovoltaic diodes the same. [Structure] A plurality of island regions 3 of single-crystal silicon insulated and separated by an insulating film 2 are arranged on a silicon substrate 1, and photovoltaic diodes PD _{1 to} PD ₁₃ are formed in each island region 3. The anode connecting line 4, the cathode connecting line 5, and the connecting line 6 connect the photovoltaic diodes PD _{1 to} PD ₁₃ in series. In this photovoltaic diode array, each diode PD ₁ ...
The areas of the diodes PD _{1 to} PD ₁₃ are set so as to increase from the center toward the periphery so that the amount of light received by the PD ₁₃ becomes substantially the same value. As a result, the short-circuit current values of the photovoltaic diodes in the peripheral portion and the central portion are aligned to a high value, and the photovoltaic characteristic is improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photovoltaic device.

[0002]

2. Description of the Related Art Conventionally, photovoltaic elements are elements that generate electromotive force when irradiated with light, and there are many types such as photodiodes, phototransistors, and solar cells, and their applications are switches, relays, and energy. There are various conversions. Among them, there is one that is incorporated in an integrated circuit and used as a solid-state relay. An example of the solid-state relay is disclosed in, for example, Japanese Patent Laid-Open No. 4-303973.

FIG. 8 is a partially cutaway perspective view of an example of a conventional solid state relay.

This solid-state relay is disclosed in the above-mentioned JP-A-4-303.
It is disclosed in Japanese Patent Publication No. 973. The light emitting device 3 is attached to the inner leads 36a of the lead frame, which are separated from each other.
1. The light receiving element 32 and the MOSFETs 33 and 34 are fixed to each other, and metal wires 35a to 35f are used to connect between the elements or between the elements and the internal lead 36a. The light passage 37 shown by the broken line is formed of transparent silicone resin,
Furthermore, the outer periphery of the transparent silicone resin is wrapped with white silicone resin to form a light reflecting film. The elements 31 to 34 and the internal leads 36a are sealed with an opaque silicone resin 38. After that, the frame and the tie bar are separated to separate the external lead 36b. A light emitting diode (LED) is usually used as the light emitting element 31.

FIG. 9 is an equivalent circuit diagram of the solid state relay of FIG.

The light receiving element 32 is a photovoltaic diode 42.
Photovoltaic diode array 43 formed by connecting in series
And a control circuit 47 in which two diodes 44 and 45 and a thyristor 46 are connected as shown. An electromotive force is generated in the light receiving element 32 by the light emitting diode 31. This electromotive force is supplied to the gates and sources of the MOSFETs 33 and 34 to make the MOSFETs 33 and 34 conductive and drive the solid state relay.

FIG. 10 is a plan view of the photovoltaic diode array section and the control circuit section of FIG.

The photovoltaic diode array 43 of the light receiving element 32 is formed by arranging the photovoltaic diodes 42 in a matrix on a semiconductor substrate and connecting them in series. A control circuit 47 composed of two diodes 44 and 45 and a thyristor 46 is arranged next to the photovoltaic diode array 43, and the bonding pads 48a ...
48c are arranged and connected by a connecting line 49.

FIG. 11 is a sectional view of the photovoltaic diode portion and the diode portion of FIG.

An oxide film 62 is formed on the polycrystalline silicon supporting substrate 61.
Then, two island regions 63 and 64 of N-type single crystal silicon which are surrounded by and isolated from each other are formed. A P-type diffusion layer 42a and an N-type diffusion layer 42b are formed in the island region 63 of N-type single crystal silicon to form the photovoltaic diode 42. Similarly,
The P-type diffusion layer 44 is formed in the island region 64 of N-type single crystal silicon.
The diode 44 is formed by forming a and the N type diffusion layer 44b. An oxide film 65 is provided on the surface, a phosphorus-diffused polycrystalline silicon layer 66 is provided thereon as a translucent conductive layer, and an interlayer SiO ₂ film 67 is provided thereon. P-type diffusion layers 42a, 44
A hole for making contact with a and the N type diffusion layers 42b and 44b is opened, and aluminum wirings 68a to 68d are formed. Then, the entire surface is covered with the nitride film 69.

FIG. 12 is a perspective view showing the state of the photovoltaic element illuminated by the light emitting diode.

Since the light emitting diode 31 is a light source that can be regarded as a point light source, the light beam spreads in a conical shape and the light receiving element 32 is formed.
Irradiate.

FIG. 13 is a light intensity distribution diagram in the X-axis direction of the photovoltaic element illuminated by the light emitting diode.

The light intensity of the light receiving surface of the light receiving element 32 is inversely proportional to the square of the distance from the light emitting diode 31, which is a light source. Therefore, the light intensity is highest at the center of the light receiving element 32 and becomes lower toward the periphery.

FIG. 14 is a VI characteristic diagram of a conventional photovoltaic element.

When illuminated by a light emitting diode, the short circuit current generated in the photovoltaic diode 42 is approximately proportional to the amount of light incident on the light receiving surface. Thus, the central photovoltaic diode exhibits a high short circuit current and the peripheral photovoltaic diode exhibits a low short circuit current. Then, the short-circuit current of the photovoltaic diode array is the same as the lowest short-circuit current value in the photovoltaic diode array, which is a low value. The open circuit voltage is the sum of the open circuit voltages of the diodes connected in series. It is known that the open circuit voltage has little dependence on the amount of incident light and is mainly determined by the material.

[0017]

In the above-mentioned photovoltaic element, each photovoltaic diode 42 is designed to have the same area. However, as shown in FIG. 12 and FIG. 13, since the irradiation light spreads in a conical shape, the amount of light received by the photovoltaic diode 42 decreases from the center toward the periphery, and the short-circuit current value also decreases accordingly. The short circuit current value of the entire power diode array will be the same as the lowest short circuit current value. Even though the central photovoltaic diode 42 has a high short circuit current, the short circuit current value of the entire photovoltaic diode array is always low,
There is a problem that the photoelectric conversion efficiency is poor and it is difficult to obtain good photovoltaic characteristics.

An object of the present invention is to make the short-circuit current value of each photovoltaic diode high so that the photoelectric conversion efficiency is improved by equalizing the received light amount of the photovoltaic diodes in the central portion and the peripheral portion. It is to provide a photovoltaic element that can obtain a photovoltaic characteristic.

[0019]

SUMMARY OF THE INVENTION The present invention is a photovoltaic device having photovoltaic diodes formed in island regions of single crystal silicon which are separated from each other by an insulating film provided on a silicon substrate and arranged in a matrix. In the power element, the area of the photovoltaic diode has an area that increases from the center of the photovoltaic element toward the periphery so that the amount of light received by each of the photovoltaic diodes becomes approximately the same value. And

The present invention is characterized in that the area of the photovoltaic diode is determined such that the product of the intensity of light received by the photovoltaic diode and the area thereof has a substantially constant value.

The present invention is characterized in that the array pattern of the photovoltaic diodes is formed by a combination of rectangular photovoltaic diodes.

The present invention is characterized in that the array pattern of the photovoltaic diodes is formed by a combination of square and rectangular photovoltaic diodes.

The present invention is characterized in that the array pattern of the photovoltaic diodes is formed by a combination of square, rectangular and L-shaped hexagonal photovoltaic diodes.

The present invention is characterized in that the arrangement pattern of the photovoltaic diodes is formed by combining triangular and trapezoidal photovoltaic diodes.

The present invention is characterized in that the arrangement pattern of the photovoltaic diodes is formed in a two-fold rotational symmetry or a four-fold rotational symmetry with the center of the photovoltaic element as a rotation axis.

[0026]

According to the present invention, the areas of the photovoltaic diodes are not equal, and the areas of the photovoltaic diodes are increased from the center of the photovoltaic element toward the periphery thereof so that each photovoltaic diode is The amount of light received is set to be approximately the same. As a result, the short-circuit currents of the central photovoltaic cells and the peripheral photovoltaic diodes become the same, and the short-circuit currents of the entire photovoltaic diodes can be made high, and the photovoltaic characteristics can be improved.

The area of the photovoltaic diode is determined so that the product of the intensity of light received by the photovoltaic diode and the area thereof (= the amount of received light) has a substantially constant value.

In order for the amount of light received by the photovoltaic diode to be approximately the same value and to fit within the quadrangular chip without any gap, the photovoltaic diode has various rectangular outer shapes and a rectangular set. An array pattern of photovoltaic diodes may be formed together.

The array pattern of photovoltaic diodes can be formed by a combination of square and rectangular photovoltaic diodes.

The array pattern of photovoltaic diodes can be formed by a combination of square, rectangular, and L-shaped hexagonal photovoltaic diodes.

The photovoltaic diode array pattern can be formed by combining the photovoltaic diodes having a triangular shape and a trapezoidal shape.

In order to fit the photovoltaic diodes in the rectangular chip without any space, the arrangement pattern of the photovoltaic diodes is two-fold rotational symmetry or four times with the center of the photovoltaic element as the axis of rotation. It is preferable to form it in rotational symmetry.

[0033]

1 is a plan view of a first embodiment of a photovoltaic element of the present invention.

The insulating film 2 is provided on the silicon substrate 1 and
A plurality of isolated single crystal silicon island regions 3 in the vertical and horizontal directions
The photovoltaic diode PD in each island region 3.₁~
PD ₁₃To form a photovoltaic diode array consisting of
It A control circuit that controls the operation of this photovoltaic diode
The part is not shown, but next to this array as in FIG.
To form. The island region 3 of single crystal silicon is formed by the insulating film 2.
The state in which they are separated from each other is the same as in FIG. light
Electromotive force diode PD₁₁Connect the anode to the anode connection wire 4
Connected to a positive potential power source by a photovoltaic diode PD₁₃
Connect the cathode of the to the negative potential power supply by the cathode connection line 5.
To do. Photovoltaic diode PD by connecting line 6₁₁The Kaso
Photovoltaic diode PD next to₉Connected to the anode of
Photovoltaic diode PD₉Photovoltaic next to the cathode
Power diode PD_TenConnect to the anode of. And so on
Then connect the connection line 6 to the photovoltaic diode PD₁~ PD₁₃Straight
Connect in columns.

Odors in this photovoltaic diode array
Photovoltaic diode PD₁~ PD ₁₃Each of receive
Photovoltaic diode PD so that the light intensity is almost the same value
₁~ PD₁₃Area increases from the center to the periphery
Is set to be. Photovoltaic diode PD
₁~ PD₁₃Area of S_iWhen (i = 1 to 13),
Photovoltaic diode PD in the center₁Area S₁Is the best
Photovoltaic diode PD that is small and outside of it₂~ PD_Five
Has the same area as S₁The larger, the photovoltaic die outside it
Aude PD₆~ PD₉Has the same area as S₆Bigger and up
Outer photovoltaic diode PD_Ten~ PD₁₃The area of
It is set large. As a representative, photovoltaic
De PD₁, PD₂, PD₆, PD₁₁To show the area ratio
Then S₁: S₂: S₆: S₁₁= 1: 2.4: 2.8
8: 3.12.

Assuming that the amount of light received by each of the photovoltaic diodes PD _{1 to} PD ₁₃ is P _i (i = 1 to 13), the product of the amount of light and the area becomes a constant value, that is, P ₁ S ₁ = P ₂ S ₂ = ... = P ₁₃ S ₁₃ = constant value (1) The light quantity and area are determined so that (1) holds. However, it is actually difficult to design the equation (1) exactly. Therefore, in reality, P ₁ S ₁ ≈P ₂ S ₂ ≈ ... ≈P ₁₃ S ₁₃ ≈constant value (2) is designed.

Photovoltaic diode PD ₁ of the first embodiment
The array pattern of PD ₁₃ to PD ₁₃ is formed by combining square and rectangular photovoltaic diodes. The array pattern has four-fold rotational symmetry because it forms the same figure every 90 ° rotation about the center of the photovoltaic diode array as the axis of rotation.

FIG. 2 is a perspective view and a plan view for explaining the illumination calculation of the solid-state relay. As shown in FIG. 2A, it is assumed that a plane H separated by a distance h by a light source (light emitting diode) L having a light intensity I [cd] is illuminated by a circle having a radius R. Illuminance E _{r at} a point r [m] from the center point directly below the light source L
E _r = Icos θ / d ² = Ih / d ³ = Ih / (h ² + r ² ) ^3/2 [lx] (3) With a radius r and a width dr as indicated by the diagonal lines in FIG. Considering the torus, since the area dS of the torus is dS = 2πrdr, the luminous flux F _r of light illuminating the torus is F _r = ∫E _r dS = 2π∫E _r rdr [lx ] (4) The light flux F ₁ of the light illuminating the circle of radius r _{1 ^{is, F 1 = 2πIh∫ 0 r1 r}} (h 2 + r 2) -3/2 dr = 2πI (1-cosθ 1) and [lx] ... (5) Become. Similarly, the light flux of the light illuminating the circle of radius r ₂ F ₂
Becomes F ₂ = 2πI (1-cos θ ₂ ) [lx] (6). In general, the light illuminating the circle of radius r _j light flux F _j
Becomes F _j = 2πI (1-cos θ _j ) [lx] (7). The light flux F ₁₂ of the light that irradiates the torus from the radius r ₁ to the radius r ₂ is F ₁₂ = F ₂ −F ₁ = 2πI (cos θ ₁ −cos θ ₂ ) [lx] (8) Light of the light flux F ₂₃ for irradiating the annular band from the radius r ₂ to the radius r _{3 is, F 23 = F 3 -F 2} = 2πI (cosθ 2 -cosθ 3) a [lx] ... (9). In general, the light flux F _ij of light that irradiates the annular ring from the radius r _i to the radius r _j is F _ij = F _j −F _i = 2πI (cos θ _i −cos θ _j ) [lx] (10) .

The above idea and formula are applied to the first embodiment.
Then, it becomes as shown in FIG. That is, in the center
A photovoltaic diode PD₁The radius of the circle surrounding₁,
Photovoltaic diode PD on the outside₂~ PD_FiveCircle surrounding
The radius of r₂, The photovoltaic diode PD outside it₆~
PD₉The radius of the circle surrounding₃The outermost photovoltaic dio
PD_Ten~ PD₁₃The radius of the circle surrounding_FourAnd Photovoltaic
Power diode PD₁Is the radius r₁Inscribed in the circle
, Photovoltaic diode PD₁The amount of light received by 2F₁/
π. Diode PD₁Size is required
Determined from the short-circuit current value, the radius r₁Was decided
It Radius r₁To radius r₂Photovoltaic in the torus up to
If four diodes are provided, the radius r₂Die on a circle
Aude PD ₁~ PD_FiveThe square created by is inscribed in the die
Aude PD₁~ PD_FiveThe amount of light received by 2F₂/ Π
It Therefore, four diodes PD₂~ PD_FiveReceived by
Light intensity is 2F₂/ Π to diode PD₁Received by
Light intensity 2F₁Value obtained by subtracting / π 2 / π-2F₁/ Π = 2 (F
₂-F₁) / Π, which is the diode PD₁Received by
2F₁It should be four times / π. 2 (F₂-F₁) / Π = 4 × 2F₁/ Π ∴ (F₂-F₁) = 4F₁ Therefore, the radius r₁To radius r₂Luminous flux illuminating the torus of
F₁₂Is F₁₂= (F₂-F₁) = 4F₁= 8πI (1-cos θ₁) [Lx] (11) It is calculated backward from this and the radius r₂You should ask. This
Radius r₂In the annular zone,
Photodiode PD by allocating 4 ions₂
~ PD_FiveThe amount of light received by each of the
De PD₁It is almost the same as the amount of light received by. Photovoltaic die
Aude PD₂~ PD_FiveThe area of is determined in this way
It

Next, assuming that four photovoltaic diodes and four outermost photovoltaic diodes each interrupt about 3/4 in an annular band from radius r ₂ to radius r ₃ , since photovoltaic diodes in the annular band is that seven entering, which determines the _{F 23 = 7F 1 = 14πI (} 1-cosθ 1) radius r ₃ such that [lx] ... (12) Good. Outermost radius r
₄ is the radius that illuminates the entire photovoltaic diode array.

Since the intensity of the light irradiating the photovoltaic diode PD ₁ at the center is the strongest, the photovoltaic diode P 1
The maximum short-circuit current of D ₁ is as described in the section of the related art. Therefore, if the required short-circuit current value is determined, the design value of the photovoltaic diode PD ₁ is determined. Equation (11), is evident from (12), because the light flux F _12, F ₂₃ is determined from equation (5) of the light flux of the photovoltaic diode PD _1, the photovoltaic diode PD ₁
Once the design value of is determined, it can be obtained later by calculation. Assuming that the open circuit voltage of each photovoltaic diode PD _i (i = 1 to n) is V _i and the required open circuit voltage is V ₀ , V ₀ = Σ _{i = 1} ⁿ V _i = n × V _i Since (13), the number of diodes n is determined. In the first embodiment, the number of diodes n = 13 due to the open circuit voltage.

FIG. 3 is a plan view of a second embodiment of the photovoltaic element of the present invention.

In the photovoltaic diode array of the second embodiment, the array pattern of photovoltaic diodes is formed by a combination of square and rectangular photovoltaic diodes. As the amount of light received by each of the photovoltaic diode PD ₁ -PD ₁₇ becomes substantially the same value, _{i.e., P 1 S 1 ≒ P 2} S 2 ≒ ······· ≒ P 17 S 17 ≒ constant value It is the same as that of the first embodiment to design so that In the second embodiment, the number of diodes n = 17 because of the open circuit voltage. This array pattern has four-fold rotational symmetry because it forms the same figure every 90 ° rotation about the center of the photovoltaic diode array as the axis of rotation.

FIG. 4 is a plan view of a third embodiment of the photovoltaic element of the present invention.

In the photovoltaic diode array of the third embodiment, the photovoltaic diode array pattern is formed by combining square, rectangular and L-shaped hexagonal photovoltaic diodes. Photovoltaic diodes PD _{1 to} PD ₁₃
It is designed so that the amount of light received by each of the above becomes approximately the same value, that is, P ₁ S ₁ ≈P ₂ S ₂ ≈ ... ≈P ₁₃ S ₁₃ ≈constant value holds. This is the same as the first embodiment. In the third embodiment, the number of diodes n = 13 due to the open circuit voltage. This array pattern has four-fold rotational symmetry because it forms the same figure every 90 ° rotation about the center of the photovoltaic diode array as the axis of rotation.

FIG. 5 is a plan view of a fourth embodiment of the photovoltaic element of the present invention.

In the photovoltaic diode array of the fourth embodiment, the photovoltaic diode array pattern is formed by combining only rectangular photovoltaic diodes.
As the amount of light received by each of the photovoltaic diode PD ₁ -PD ₁₂ is approximately the same value, _{i.e., P 1 S 1 ≒ P 2} S 2 ≒ ······· ≒ P 12 S 12 ≒ constant value It is the same as that of the first embodiment to design so that In the fourth embodiment, the number of diodes n = 12 because of the open circuit voltage. This array pattern has a two-fold rotational symmetry because the pattern becomes the same every 180 ° rotation about the center of the photovoltaic diode array as the rotation axis.

FIG. 6 is a plan view of the fifth embodiment of the photovoltaic element of the present invention.

In the photovoltaic diode array of the fifth embodiment, the photovoltaic diode array pattern is formed by a combination of triangular and trapezoidal photovoltaic diodes. As the amount of light received by each of the photovoltaic diode PD ₁ -PD ₁₂ is approximately the same value, _{i.e., P 1 S 1 ≒ P 2} S 2 ≒ ······· ≒ P 12 S 12 ≒ constant value It is the same as that of the first embodiment to design so that In the fifth embodiment, the number of diodes n is 12 because of the open circuit voltage. This array pattern has four-fold rotational symmetry because it forms the same figure every 90 ° rotation about the center of the photovoltaic diode array as the axis of rotation.

FIG. 7 is a VI characteristic diagram of the embodiment of the present invention.

In the present invention, the area of the photovoltaic diode is increased from the central portion of the element toward the periphery so that the amount of light incident on the light receiving surface of the photovoltaic diode becomes a constant value. The generated short circuit current is aligned with the short circuit current value of the photovoltaic diode at the center of the highest short circuit current value. Therefore, the short-circuit current value is higher than that of the conventional product. The open circuit voltage is the same as the conventional product because it is the sum of the open circuit voltages of the diodes connected in series.

[0052]

As described above, according to the present invention, the area of the photovoltaic diode increases from the center of the light receiving element toward the periphery so that the amount of light received by each of the photovoltaic diodes becomes approximately the same value. Since I set it like this,
The short-circuit current value of the photovoltaic diode in the peripheral part is aligned with the highest short-circuit current value of the photovoltaic diode in the central part, the short-circuit current value of the entire photovoltaic diode array is increased, and the photoelectric conversion efficiency is improved. A photovoltaic element having good photovoltaic characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of a photovoltaic device of the present invention.

2A and 2B are a perspective view and a plan view for explaining an illumination calculation of a solid-state relay.

FIG. 3 is a plan view of a second embodiment of the photovoltaic element of the present invention.

FIG. 4 is a plan view of a third embodiment of the photovoltaic device of the present invention.

FIG. 5 is a plan view of a fourth embodiment of the photovoltaic element of the present invention.

FIG. 6 is a plan view of a fifth embodiment of the photovoltaic element of the present invention.

FIG. 7 is a VI characteristic diagram of the example of the present invention.

FIG. 8 is a partially cutaway perspective view of an example of a conventional solid state relay.

9 is an equivalent circuit diagram of the solid-state relay of FIG.

10 is a plan view of the photovoltaic diode array section and control circuit section of FIG. 9. FIG.

11 is a cross-sectional view of the photovoltaic diode portion and the diode portion of FIG.

FIG. 12 is a perspective view showing a state of a photovoltaic element illuminated by a light emitting diode.

FIG. 13 is a light intensity distribution diagram in the X-axis direction of a photovoltaic element irradiated with a light emitting diode.

FIG. 14 is a VI characteristic diagram of an example of a conventional photovoltaic device.

[Explanation of symbols]

 1 Silicon Substrate 2 Insulating Film 3 Island Area 4 Anode Connection Line 5 Cathode Connection Line 6 Connection Line

Claims (7)

[Claims] 1. A photovoltaic diode PD _i (i = i = _i ) formed in island regions of single crystal silicon which are separated from each other by an insulating film provided on a silicon substrate and are arranged in the vertical and horizontal directions.
1-n), the area S _i (i) of each of the photovoltaic diodes PD _i (i = 1 to n) has a substantially equal value so that the amount of light received by each of the photovoltaic diodes PD _i (i = 1 to n) is substantially the same. = 1 to n) has an area that increases from the center of the photovoltaic element toward the periphery thereof. 2. The photovoltaic diode PD _i (i = 1
~ N) is equal to the photovoltaic diode PD _i (i = 1)
To n) are defined so that the product of the intensity of the light received by n) and the area thereof are substantially constant. 3. The photovoltaic diode PD _i (i = 1
2. The photovoltaic element according to claim 1, wherein the arrangement pattern of (1) to (n) is formed by a combination of rectangular photovoltaic diodes. 4. The photovoltaic diode PD _i (i = 1
2. The photovoltaic element according to claim 1, wherein the array patterns (1) to (n) are formed by combining square and rectangular photovoltaic diodes. 5. The photovoltaic diode PD _i (i = 1
2. The photovoltaic element according to claim 1, wherein the arrangement pattern of (1) to (n) is formed by a combination of square, rectangular and L-shaped hexagonal photovoltaic diodes. 6. The photovoltaic diode PD _i (i = 1
2. The photovoltaic element according to claim 1, wherein the arrangement pattern of (1) to (n) is formed by a combination of triangular and trapezoidal photovoltaic diodes. 7. The arrangement pattern of the photovoltaic diodes is formed in a two-fold rotational symmetry or a four-fold rotational symmetry with the center of the photovoltaic element as a rotation axis. Photovoltaic device.