Patent Publication Number: US-2019198260-A1

Title: Photoelectric conversion device

Description:
TECHNICAL FIELD 
     The present invention relates to a photoelectric conversion device having a photoelectric conversion element and an electric storage part. 
     BACKGROUND 
     As a photoelectric conversion element, a photoelectric conversion element using dyes attracts attention since it is inexpensive and can obtain high photoelectric conversion efficiency, and various developments on photoelectric conversion elements using dyes are performed. 
     The photoelectric conversion element using dyes generally includes a photoelectric conversion cell which has an electrode substrate, a counter substrate facing the electrode substrate, an oxide semiconductor layer provided on the electrode substrate or the counter substrate, a dye supported on the oxide semiconductor layer, a ring-shaped sealing portion bonding the electrode substrate and the counter substrate, and an electrolyte which is arranged in a cell space surrounded by the electrode substrate, the counter substrate and the sealing portion and contains a redox pair such as iodine/iodide ion. The photoelectric conversion element is generally used with it connected to an electric storage part such as an external load circuit or a secondary battery. That is, power generated in the photoelectric conversion element is consumed in the external load circuit or accumulated in the electric storage part. 
     However, in a case where the external load circuit is not operating with power generated in the photoelectric conversion element, or in a case where the electric storage part is in a fully charged state, power consumption and accumulation are not performed for a long time. That is, the photoelectric conversion element is in an open circuit state over a long period of time. In this case, a state in which the high voltage is generated with light irradiated continues for a long time, and electrons generated by photoexcitation of the dye are charged to the conduction band of the oxide semiconductor layer. However, since an open circuit state continues over a long period of time, electrons move from the oxide semiconductor layer to the electrolyte. As a result, the reduction reaction of iodine proceeds, and the ratio of iodine and iodide ions in the electrolyte is changed to lower power generation performance. 
     Accordingly, to prevent a photoelectric conversion element from being in the open circuit state over a long period of time, it is suggested to provide a deterioration suppression control device for the photoelectric conversion element in a circuit where a photoelectric conversion element, and an electric storage part capable of charging a voltage output from the photoelectric conversion element are connected (see Patent document 1 below). The deterioration suppression control device includes: a current detection part detecting a current from the photoelectric conversion element; a voltage detection part detecting a voltage output from the photoelectric conversion element, and connects a positive electrode and a negative electrode of the photoelectric conversion element by a short-circuit part based on the current detected by the current detection part and the voltage detected by the voltage detection part. 
     PATENT DOCUMENT 
     Patent document 1: JP5,618134B 
     SUMMARY 
     However, the deterioration suppression control device described in the patent document 1 may cause the photoelectric conversion element to break, as explained below. 
     The deterioration suppression control device described in the patent document 1 connects the positive electrode and the negative electrode of the photoelectric conversion element by the short-circuit part, for example, when the current detected by the current detection part becomes sufficiently small. For this reason, an excessive current flows in the photoelectric conversion element, and the photoelectric conversion element may be broken. 
     Therefore, required is a photoelectric conversion device preventing destruction of a photoelectric conversion element in a circuit where the photoelectric conversion element and an electric storage part capable of charging the voltage output from the photoelectric conversion element, and having excellent durability. 
     One or more embodiments of the present invention provide a photoelectric conversion element preventing destruction of a photoelectric conversion element and having excellent durability. 
     One or more embodiments of the present invention are directed to a photoelectric conversion device including a photoelectric conversion element, a voltage conversion part boosting a voltage output from the photoelectric conversion element, and an electric storage part capable of being charged to a voltage output from the voltage conversion part; and a load part which is arranged in parallel to the electric storage part and is used to apply a voltage of the electric storage part, a voltage monitoring part monitoring the voltage of the electric storage part, a switching part switching a first state in which a voltage output from the voltage conversion part is applied only to the electric storage part, and a second state in which the voltage output from the voltage conversion part is not applied to any of the electric storage part and the load part, and a controlling part controlling the switching part so that the electric storage part is discharged and a voltage is applied to the load part by switching the switching part to the second state in a case where the voltage of the electric storage part monitored by the voltage monitoring part reaches a full charge voltage of the electric storage part, and controlling the switching part so that the electric storage part is charged by switching the switching part to the first state in a case where the voltage of the electric storage part monitored by the voltage monitoring part becomes less than the full charge voltage of the electric storage part, wherein the photoelectric conversion element includes at least one photoelectric conversion cell, and wherein the photoelectric conversion cell includes an electrode substrate, a counter substrate facing the electrode substrate, an oxide semiconductor layer provided on the electrode substrate or the counter substrate, a dye supported on the oxide semiconductor layer, and an electrolyte which is disposed between the electrode substrate and the counter substrate, and which contains a redox pair. 
     According to the photoelectric conversion device of one or more embodiments, when light is irradiated to the photoelectric conversion element, power generation is performed in the photoelectric conversion element. Then, the voltage output from the photoelectric conversion element is boosted at the voltage conversion part. At this time, in a case where the voltage of the electric storage part monitored by the voltage monitoring part is less than the full charge voltage of the electric storage part, the switching part is controlled by the controlling part so that the electric storage part is charged by switching the switching part to the first state where the voltage output from the voltage conversion part is applied only to the electric storage part. In a case where the voltage of the electric storage part monitored by the voltage monitoring part reaches the full charge voltage of the electric storage part, the switching part is immediately controlled by the controlling part so that the electric storage part is discharged and a voltage is applied to the load part by switching the switching part to the second state where the voltage output from the voltage conversion part is not applied to any of the electric storage part and the load part. Then, in a case where the voltage of the electric storage part monitored by the voltage monitoring part becomes less than the full charge voltage of the electric storage part, the switching part is immediately controlled by the controlling part so that the electric storage part is charged by switching the switching part to the first state where the voltage output from the voltage conversion part is applied only to the electric storage part. Thus, it is sufficiently suppressed that the photoelectric conversion element is in an open circuit state over a long period of time. Therefore, it is fully suppressed that after electrons generated by photoexcitation of the dye are charged to the conduction band of the oxide semiconductor layer, electrons are transferred from the oxide semiconductor layer to the electrolyte and the reduction reaction of the oxidizing agent in the redox pair proceeds. As a result, the change in the ratio of the redox pair in the electrolyte is sufficiently suppressed, and the durability of the photoelectric conversion element is improved. In addition, according to the photoelectric conversion device of one or more embodiments of the present invention, in a case where the switching part is controlled by the controlling part so that the electric storage part is charged by switching the switching part to the first state where the voltage output from the voltage conversion part is applied only to the electric storage part as well as in a case where the switching part is controlled by the controlling part so that the electric storage part is discharged and a voltage is applied to the load part by switching the switching part to the second state where the voltage output from the voltage conversion part is not applied to any of the electric storage part and the load part, the photoelectric conversion element is not short-circuited. Therefore, it is sufficiently suppressed that an excessive current is caused to flow in the photoelectric conversion element. Accordingly, according to the photoelectric conversion device of one or more embodiments of the present invention, it is possible to prevent destruction of the photoelectric conversion element and have excellent durability. 
     In the photoelectric conversion device of one or more embodiments, specifically, the switching part includes a first switching element capable of switching a first ON state capable of applying the voltage output from the voltage conversion part to the electric storage part and a first OFF state where the voltage output from the voltage conversion part is not applied to any of the electric storage part and the load part, a second switching element switching a second OFF state where the voltage output from the voltage conversion part is not applied to the load part and a second ON state where the voltage of the electric storage part is applied to the load part, and the controlling part controls so that the electric storage part is discharged and a voltage is applied to the load part by switching the switching part to the second state by controlling the first switching element to the first OFF state and controlling the second switching element to the second state in a case where the voltage of the electric storage part monitored by the voltage monitoring part reaches the full charge voltage of the electric storage part, or so that the electric storage part is charged by switching the switching part to the first state by controlling the first switching element to the first ON state and controlling the second switching element to the second OFF state in a case where the voltage of the electric storage part monitored by the voltage monitoring part becomes less than the full charge voltage of the electric storage part. 
     In the photoelectric conversion device of one or more embodiments, the first switching element may be a p-channel MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) and the second switching element may be a re-channel MOSFET. 
     In this case, since power consumption in the first switching element and the second switching element is sufficiently small, the power consumption in the entire photoelectric conversion device can be reduced. 
     In the photoelectric conversion device of one or more embodiments, the controlling part and the voltage monitoring part may be electrically connected, the first switching element may have a first gate electrode, the second switching element may have a second gate electrode, the first gate electrode and the controlling part may be electrically connected, and the controlling part may be capable of applying different potentials to the first gate, and the second gate electrode and the controlling part may be electrically connected, and the controlling part may be capable of applying different potentials to the second gate electrode. 
     In this case, since the controlling part applies different potentials to the first gate electrode of the first switching element based on the voltage monitored by the voltage monitoring part, the first switching element can be easily switched to the first ON state and the first OFF state. In addition, since the controlling part applies different potentials to the second gate electrode of the second switching element based on the voltage monitored by the voltage monitoring part, the second switching element can be easily switched to the second ON state and the second OFF state. 
     In the photoelectric conversion device of one or more embodiments, the electric storage part is, for example, a secondary battery or a capacitor. 
     In the photoelectric conversion device of one or more embodiments, the load part is, for example, a resistance element. 
     According to one or more embodiments of the present invention, a photoelectric conversion element preventing destruction of a photoelectric conversion device and having excellent durability is provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a circuit diagram illustrating a photoelectric conversion device of one or more embodiments of the present invention; 
         FIG. 2  is a circuit diagram illustrating the photoelectric conversion device of one or more embodiments of the present invention; 
         FIG. 3  is a circuit diagram illustrating the photoelectric conversion device of one or more embodiments of the present invention; 
         FIG. 4  is a cross-sectional view illustrating an example of the photoelectric conversion element of  FIGS. 1-3 ; 
         FIG. 5  is a plan view illustrating a part of the photoelectric conversion element of  FIG. 4 ; 
         FIG. 6  is a plan view illustrating a pattern of a transparent conductive layer in the photoelectric conversion element of  FIG. 4 ; 
         FIG. 7  is a plan view illustrating an electrode substrate on which a coupling portion for fixing a back sheet, and an oxide semiconductor layer are formed in accordance with one or more embodiments. 
         FIG. 8  is a circuit diagram illustrating the photoelectric conversion device of one or more embodiments of the present invention; and 
         FIG. 9  is a circuit diagram illustrating the photoelectric conversion device of one or more embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the photoelectric conversion device of one or more embodiments of the present invention will be described in detail with reference to the drawings.  FIGS. 1 to 3  are circuit diagrams illustrating the photoelectric conversion device of one or more embodiments of the present invention.  FIG. 1  illustrates a state where light is not irradiated to the photoelectric conversion element,  FIG. 2  is a state where light is irradiated to the photoelectric conversion element and the electric storage part (an electric storage) is charged, and  FIG. 3  is a state where light is irradiated to the photoelectric conversion element and the electric storage part is discharged. 
     As illustrated in  FIG. 1 , a photoelectric conversion device  200  includes a photoelectric conversion element  100 ; a voltage conversion part  101  boosting a voltage output from the photoelectric conversion element  100 ; an electric storage part  102  capable of being charged up to a voltage output from the voltage conversion part  101  (a voltage converter); a load part  103  (a load) which is arranged in parallel to the electric storage part  102  and applies a voltage of the electric storage part  102 ; a voltage monitoring part  104  (a voltage monitor) monitoring the voltage of the electric storage part  102 ; a switching part  105  (a main switch) switching a first state in which a voltage output from the voltage conversion part  101  is applied only to the electric storage part  102 , and a second state in which the voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103 ; and a controlling part  106  (a controller) controlling the switching part  105  so that the electric storage part  102  is discharged and a voltage is applied to the load part  103  by switching the switching part  105  to the second state in a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  reaches a full charge voltage of the electric storage part  102 , and controlling the switching part  105  so that the electric storage part  102  is charged by switching the switching means  105  to the first state in a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  becomes less than the full charge voltage of the electric storage part  102 . 
     It is sufficient that the voltage conversion part  101  is a part boosting a voltage output from the photoelectric conversion element  100 . As the voltage conversion part  101 , for example, a DC/DC converter can be used. 
     It is sufficient that the electric storage part  102  is a part capable of being charged up to a voltage boosted by the voltage conversion part  101 . As the electric storage part  102 , for example, a secondary battery or a capacitor can be used. In addition, the full charge voltage of the electric storage part  102  is less than or equal to the voltage output from the voltage conversion part  101 . 
     It is sufficient that the load part  103  is a part consuming power. Examples of the load part  103  include, for example, a resistance element. 
     It is sufficient that the voltage monitoring part  104  is a part capable of monitoring a voltage of the electric storage part  102 . As the voltage monitoring part  104 , for example, a voltage monitoring IC or the like can be used. 
     Specifically, the switching part  105  includes a first switching element  105   a  (a first switch) and a second switching element  105   b  (a second switch). In one or more embodiments, the first switching element  105   a  is composed of a p-channel MOSFET, and the second switching element  105   b  is composed of a n-channel MOSFET. In the p-channel MOSFET, an electrode (a first gate electrode) is formed on a partial region of a surface of a n-type semiconductor substrate via an oxide film such as silicon oxide, p-type regions are provided on both sides of the partial region, and electrodes are formed on each of the p-type regions. In the n-channel MOSFET, an electrode (second gate electrode) is formed on a partial region of a surface of a p-type semiconductor substrate via an oxide film such as silicon oxide, n-type regions are provided on both sides of the partial region and electrodes are formed on the n-type regions. In addition, in any of the p-channel MOSFET and the n-channel MOSFET, the electrode on the oxide film is a gate electrode, and the electrodes on both sides of the gate electrode are a source electrode and a drain electrode, respectively. 
     The controlling part  106  is electrically connected to the voltage monitoring part  104 . Further, the controlling part  106  is electrically connected to the first gate electrode of the first switching element  105   a  and is capable of applying different potentials to the first gate electrode. In addition, the controlling part  106  is electrically connected to the second gate electrode of the second switching element  105   b  and is capable of applying different potentials to the second gate electrode. 
     The first switching element  105   a  is capable of switching a first ON state capable of applying the voltage output from the voltage conversion part  101  to any of the electric storage part  102  and the load part  103 , and a first OFF state where the voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103 . Specifically, when a low potential is applied to a gate (G) which is the gate electrode of the first switching element  105   a  by the controlling part  106 , a current flows from a source (S) which is a source electrode to a drain (D) which is a drain electrode since the first switching element  105   a  is a p-channel MOSFET. Therefore, the first switching element  105   a  becomes the first ON state capable of applying a voltage output from the voltage conversion part  101  to any of the electric storage part  102  and the load part  103 . 
     On the other hand, when a high potential is applied to a gate (G) of the first switching element  105   a  by the controlling part  106 , a current does not flow from the source (S) to the drain (D) since the first switching element  105   a  is a p-channel MOSFET. Therefore, the first switching element  105   a  becomes the first OFF state where a voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103 . 
     The second switching element  105   b  switches a second OFF state where the voltage output from the voltage conversion part  101  is not applied to the load part  103  and a second ON state where the voltage of the electric storage part  102  is applied to the load part  103 . Specifically, when a low potential is applied to the gate (G) of the second switching element  105   b  by the controlling part  106 , no current flows from the source (S) to the drain (D) since the second switching element  105   b  is a n-channel MOSFET. Therefore, the second switching element  105   b  becomes the second OFF state where the voltage output from the voltage conversion part  101  is not applied to the load part  103 . 
     On the other hand, when a high potential is applied to the gate (G) of the second switching element  105   b  by the controlling part  106 , a current flows from the source (S) to the drain (D) since the second switching element  105   b  is a n-channel MOSFET. Therefore, the second switching element  105   b  becomes the second ON state where a voltage of the electrical storage part  102  is applied to the load part  103 . 
     Here, the controlling part  106  makes the electric storage part  102  discharge and makes a voltage apply to the load part  103  by switching the switching part to the second state by controlling the first switching element  105   a  to the first OFF state and controlling the second switching element  105   b  to the second ON state in a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  reaches the full charge voltage of the electric storage part  102 . Specifically, the first switching element  105   a  is controlled to the first OFF state and the second switching element  105   b  is controlled to the second ON state by applying identical high potentials to the gates (G) of the first switching element  105   a  and the second switching element  105   b  from the controlling part  106 . 
     On the other hand, in a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  becomes less than the full charge voltage of the electric storage part  102 , the controlling part controls so that the electric storage part  102  is charged by switching the switching part to the first state by controlling the first switching element  105   a  to the first ON state and controlling the second switching element  105   b  to the second OFF state. Specifically, the first switching element  105   a  is controlled to the first ON state and the second switching element  105   b  is controlled to the second OFF state by applying identical low potentials to the gates (G) of the first switching element  105   a  and the second switching element  105   b  from the controlling part  106 . 
       FIG. 4  is an end view of a cut surface illustrating one example of the photoelectric conversion element of  FIGS. 1-3 ,  FIG. 5  is a plan view illustrating a part of the photoelectric conversion element of  FIG. 4 ,  FIG. 6  is a plan view illustrating a pattern of a transparent conductive layer in the photoelectric conversion element of  FIG. 4  and  FIG. 7  is a plan view illustrating an electrode substrate on which a coupling portion for fixing a back sheet, and an oxide semiconductor layer are formed. 
     As illustrated in  FIG. 4 , the photoelectric conversion device  100  includes a plurality (four in  FIG. 4 ) of photoelectric conversion cells (hereinafter referred to as “cells” in some cases)  50 ; and a back sheet  80  provided so as to cover a surface of the cell  50  on the side opposite to the light incident surface  50   a . As illustrated in  FIG. 5 , the plurality of cells  50  are connected in series by wiring materials  60 P. Hereinafter, for convenience of explanation, the four cells  50  in the photoelectric conversion element  100  can be referred to as cells  50 A to  50 D. 
     As illustrated in  FIG. 4 , each of the plurality of cells  50  includes an electrode substrate  10 ; a counter electrode  20  facing the electrode substrate  10 ; an oxide semiconductor layer  13  provided on the electrode substrate  10 ; a dye supported on the oxide semiconductor layer  13 ; a ring-shaped sealing portion  30 A bonding the electrode substrate  10  and the counter substrate  20 ; and an electrolyte  40  which is disposed in a cell space formed by the electrode substrate  10 , the counter substrate  20  and the ring-shaped sealing portion  30 A and which contains a redox pair. 
     The counter substrate  20  includes a conductive substrate  21  and a catalyst layer  22  which is provided on a side of the conductive substrate  21  facing the electrode substrate  10  and promotes a catalyst reaction. 
     As illustrated in  FIGS. 4 and 5 , the electrode substrate  10  includes a transparent substrate  11 ; a transparent conductive layer  12  provided on the transparent substrate  11 ; an insulating material  33  provided on the transparent substrate  11 ; and a connecting terminal  16  provided on the transparent conductive layer  12 . The transparent substrate  11  is used as a common transparent substrate of the cells  50 A to  50 D. 
     As illustrated in  FIGS. 4 and 5 , the transparent conductive layer  12  is composed of transparent conductive layers  12 A to  12 F which are provided in a state insulated from each other. That is, the transparent conductive layers  12 A to  12 F are arranged with a groove ( 90 ) interposed therebetween. Here, the transparent conductive layers  12 A to  12 D constitute the transparent conductive layers  12  of the plurality of cells  50 A to  50 D, respectively. The transparent conductive layer  12 F is the ring-shaped transparent conductive layer  12  for fixing a peripheral edge part  80   a  of the back sheet  80  (see  FIG. 4 ). 
     As illustrated in  FIG. 6 , any of the transparent conductive layers  12 A to  12 D include a quadrangular main body portion  12   a  having side edge parts  12   b  and a protruding part  12   c  protruding laterally from the side edge part  12   b  of the main body portion  12   a.    
     As illustrated in  FIG. 5 , the protruding portion  12   c  of the transparent conductive layer  12 C among the transparent conductive layers  12 A to  12 D has a projecting portion  12   d  which laterally projects with respect to the arrangement direction X of the cells  50 A to  50 D and a facing portion  12   e  which extends from the projecting portion  12   d  and faces the main body portion  12   a  of the adjacent cell  50 D via the groove  90 . 
     In the cell  50 B as well, the protruding portion  12   c  of the transparent conductive layer  12 B has the projecting portion  12   d  and the facing portion  12   e . In addition, in the cell  50 A as well, the protruding portion  12   c  of the transparent conductive layer  12 A has the projecting portion  12   d  and the facing portion  12   e.    
     In addition, the cell  50 D is already connected to the cell  50 C and there is no other cell  50  to be connected. For this reason, in the cell  50 D, the protruding portion  12   c  of the transparent conductive layer  12 D does not have a facing portion  12   e . In other words, the protruding portion  12   c  of the transparent conductive layer  12 D is composed of only the projecting portion  12   d.    
     However, the transparent conductive layer  12 D further has a first current extracting portion  12   f  for extracting the current generated in the photoelectric conversion element  100  to the outside and a connecting portion  12   g  which connects the first current extracting portion  12   f  and the main body portion  12   a  and extends along the side edge portion  12   b  of the transparent conductive layers  12 A to  12 C. The first current extracting portion  12   f  is disposed in the vicinity of the cell  50 A and on a side of the transparent conductive layer  12 A facing in the opposite direction from the transparent conductive layer  12 B. 
     On the other hand, the transparent conductive layer  12 E also includes a second current extracting portion  12   h  for extracting the current generated by the photoelectric conversion element  100  to the outside, and the second current extracting portion  12   h  is arranged in the vicinity of the cell  50 A and on a side of the transparent conductive layer  12 A facing in the opposite direction from the transparent conductive layer  12 B. The first current extracting portion  12   f  and the second current extracting portion  12   h  are arranged to be adjacent to each other via the groove  90  in the vicinity of the cell  50 A. 
     In addition, the connecting terminal  16  is provided on each of the protruding portions  12   c  of the transparent conductive layers  12 A to  12 C and the transparent conductive layer  12 E. Each connecting terminal  16  has a wiring material connecting portion  16 A which is connected to the wiring material  60 P and is provided outside the sealing portion  30 A and a wiring material non-connecting portion  16 B which is connected to the wiring material connecting portion  16 A outside the sealing portion  30 A. 
     On the other hand, as illustrated in  FIG. 5 , four wiring materials  60 P (hereinafter, in some cases, referred to as wiring material  60 P 1  to  60 P 4 , respectively) is provided on a side of the electrode substrate  10  facing the sealing portion  30 A. One end of the wiring material  60 P 1  is connected to the conductive substrate  21  of the cell  50 A and the other end of the wiring material  60 P 1  is connected to the wiring material connecting portion  16 A of the connecting terminal  16  on the transparent conductive layer  12 E. Similarly, one end of the wiring material  60 P 2  is connected to the conductive substrate  21  of the cell  50 B and the other end of the wiring material  60 P 2  is connected to the wiring material connecting portion  16 A of the connecting terminal  16  on the transparent conductive layer  12 A. One end of the wiring material  60 P 3  is connected to the conductive substrate  21  of the cell  50 C and the other end of the wiring material  60 P 3  is connected to the wiring material connecting portion  16 A of the connecting terminal  16  on the transparent conductive layer  12 B. One end of the wiring material  60 P 4  is connected to the conductive substrate  21  of the cell  50 D and the other end of the wiring material  60 P 4  is connected to the wiring material connecting portion  16 A of the connecting terminal  16  on the transparent conductive layer  12 C. 
     In addition, external connecting terminals  18   a  and  18   b  are provided on the first current extracting portion  12   f  and the second current extracting portion  12   h , respectively. 
     As illustrated in  FIG. 4 , the sealing portion  30 A, which includes a resin, includes a ring-shaped first sealing portion  31 A provided between the electrode substrate  10  and the counter substrate  20 ; and a second sealing portion  31 A which is provided to overlap with the first sealing portion  31 A and sandwiches the edge portion  20   a  of the counter substrate  20  together with the first sealing portion  31 A. Sealing portions  30 A of the adjacent two cells  50  are integrated with each other. 
     In addition, as illustrated in  FIG. 4 , an insulating material  33  is provided between the sealing portion  31 A and the groove  90  so as to enter the groove  90  between the transparent conductive layers  12 A to  12 F adjacent to each other and straddle the adjacent transparent conductive layers  12 . Specifically, the insulating material  33  enters a groove  90  formed along an edge portion of the main body portion  12   a  of the transparent conductive layer  12  of the groove  90  and covers the edge portion of the main body portion  12   a  which forms the groove  90 . 
     As illustrated in  FIG. 4 , the back sheet  80  is provided on the electrode substrate  10 . The back sheet  80  includes a laminate including a weather-resistant layer and a metal layer. The peripheral part  80   a  of the back sheet  80  is connected to the transparent conductive layers  12 D,  12 E and  12 F among the transparent conductive layers  12  via a coupling portion  14 . 
     In addition, in the transparent conductive layer  12 D, a current collecting wiring  17  having a lower resistance than that of the transparent conductive layer  12 D extends so as to pass through the main body portion  12   a , the connecting portion  12   g , and the current extracting portion  12   f  (see  FIG. 5 ). 
     In addition, as illustrated in  FIG. 5 , bypass diodes  70 A to  70 D are provided on the sealing portions  30 A of the cells  50 A to  50 D, respectively. On the other hand, the wiring material  60 P 1  and the bypass diode  70 A are connected by the wiring material  60 Q( 60 Q 1 ), the bypass diode  70 A and the bypass diode  70 B are connected by the wiring material  60 Q( 60 Q 2 ), the bypass diode  70 B and the bypass diode  70 C are connected by the wiring material  60 Q( 60 Q 3 ) and the bypass diode  70 C and the bypass diode  70 D are connected by the wiring material  60 Q( 60 Q 4 ). The wiring material  60 Q 2  is connected to the wiring material  60 P 2 , the wiring material  60 Q 3  is connected to the wiring material  60 P 3  and the wiring material  60 Q 4  is connected to the wiring material  60 P 4 . The bypass diode  70 D is connected to the projecting portion  12   d  of the transparent conductive layer  12 D of the cell  50 D via the wiring material  60 R. Accordingly, the bypass diodes  70 A to  70 D are connected in parallel to the cells  50 A to  50 D, respectively. 
     According to the photoelectric conversion device  200 , when light is irradiated to the photoelectric conversion element  100 , power generation is performed in the photoelectric conversion element  100 . Then, the voltage output from the photoelectric conversion element  100  is boosted at the voltage conversion part  101 . At this time, in a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  is less than the full charge voltage of the electric storage part  102 , the switching part  105  is controlled by the controlling part  106  so that the electric storage part  102  is charged by switching the switching part to the first state where the voltage output from the voltage conversion part  101  is applied only to the electric storage part  102  (see  FIG. 2 ). Specifically, the switching part  105  is controlled so that the electric storage part  102  is charged by switching the switching part to the first state by controlling the first switching element  105   a  to the first ON state where the voltage output from the voltage conversion part  101  can be applied to any of the electric storage part  102  and the load part  103  and controlling the second switching element  105   b  to the second OFF state where the voltage output from the voltage conversion part  101  is not applied to the load part  103 . 
     In a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  reaches the full charge voltage of the electric storage part  102 , the switching part  105  is immediately controlled by the controlling part  106  so that the electric storage part  102  is discharged and a voltage is applied to the load part  103  by switching the switching part to the second state where the voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103  (see  FIG. 3 ). Specifically, the switching part  105  is controlled so that the electric storage part  102  is discharged by switching the switching part to the first state by controlling the first switching part  105   a  to the first OFF state where the voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103  and by controlling the second switching element  105   b  to the second ON state where the voltage of the electric storage part  102  is applied to the load part  103 . In this case, since the electric storage part  102  and the load part  103  are connected in parallel, the voltage of the electric storage part  102  is applied to the load part  103  in a closed circuit connecting points A, B, C and D. That is, the electric storage part  102  is discharged. 
     In a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  becomes less than the full charge voltage of the electric storage part  102 , the switching part  105  is immediately controlled by the controlling part  106  so that the electric storage part  102  is charged by switching the switching part to the first state where the voltage output from the voltage conversion part  101  is applied only to the electric storage part  102 . 
     Thus, it is sufficiently suppressed that the photoelectric conversion element  100  is in an open circuit state over a long period of time. Therefore, it is sufficiently suppressed that after electrons generated by photoexcitation of the dye are charged to the conduction band of the oxide semiconductor layer  13 , electrons are transferred from the oxide semiconductor layer  13  to the electrolyte  40  to proceed the reduction reaction of the oxidizing agent in the redox pair. As a result, the change in the ratio of the redox pair in the electrolyte  40  is sufficiently suppressed, and the durability of the photoelectric conversion element  100  is improved. In addition, according to the photoelectric conversion device  200 , in a case where the switching part  105  is controlled by the controlling part  106  so that the electric storage part  102  is charged by switching the switching part to the first state where the voltage output from the voltage conversion part  101  is applied only to the electric storage part  102  as well as in a case where the switching part  105  is controlled by the controlling part  106  so that the electric storage part  102  is discharged and a voltage is applied to the load part  103  by switching the switching part to the second state where the voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103 , the photoelectric conversion element  100  is not short-circuited. Therefore, it is sufficiently suppressed that an excessive current is caused to flow in the photoelectric conversion element  100 . Accordingly, according to the photoelectric conversion device  200 , it is possible to prevent destruction of the photoelectric conversion element  100  and have excellent durability. 
     In the photoelectric conversion device  200 , since the first switching element  105   a  is a p-type MOSFET and the second switching element  105   b  is a n-channel MOSFET, the power consumption in the first switching element  105   a  and the second switching element  105   b  is sufficiently small. Therefore, power consumption in the entire photoelectric conversion device  200  can be reduced. 
     Further, in the photoelectric conversion device  200 , the controlling part  106  is electrically connected to the voltage monitoring part  104 . In addition, the controlling part  106  is electrically connected to the gate (G) of the first switching element  105   a  and is capable of applying different potentials to the gate (G). Moreover, the controlling part  106  is electrically connected to the gate (G) of the second switching element  105   b  and is capable of applying different potentials to the gate (G). 
     Therefore, the first switching element  105   a  can be easily switched to the first ON state and the first OFF state since the controlling part  106  applies different potentials to the gate (G) of the first switching element  105   a  based on the voltage monitored by the voltage monitoring part  104 . In addition, the second switching element  105   b  can be easily switched to the second ON state and the second OFF state since the controlling part  106  applies different potentials to the gate (G) of the second switching element  105   b  based on the voltage monitored by the voltage monitoring part  104 . 
     The present invention is not limited to the above embodiments. For example, in the above embodiments, the photoelectric conversion element  100  includes a plurality of cells  50 . However, the photoelectric conversion element  100  may include only one cell  50 . 
     Further, in the above embodiments, the first switching element  105   a  and the second switching element  105   b  may be formed of another FET such as a junction-type FET instead of the MOSFET. 
     Furthermore, in the above embodiments, the first switching element  105   a  and the second switching element  105   b  are used as the switching part  105 . However, as in a photoelectric conversion device  300  illustrated in  FIGS. 8 and 9 , a switching part  305  may be used in place of the switching part  105 . The switching part  305  switches a state in which the point A and the point A 1  are brought into conduction with each other and a state in which the point A and the point A 2  are brought into conduction with each other, by the controlling part  106 .  FIG. 8  illustrates a state where light is irradiated to the photoelectric conversion element  100  and the electric storage part  102  are charged.  FIG. 9  illustrates a state where light is irradiated to the photoelectric conversion element  100  and the electric storage part  102  are discharged. In a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  reaches the full charge voltage of the electric storage part  102 , the switching part  305  is controlled so that the electric storage part  102  is discharged and a voltage is applied to the load part  103  by switching the switching part to a second state (namely, a state where the point A and the point A 1  are brought into conduction with each other). In a case where the voltage of the electric storage part  102  monitored by the voltage monitoring part  104  becomes less than the full charge voltage of the electric storage part  102 , the switching part  305  is controlled so that the electric storage part  102  is charged by switching the switching part to a first state (namely, a state where the point A and the point A 2  are brought into conduction with each other). In this case as well, it is sufficiently suppressed that the photoelectric conversion element  100  is in an open-circuit state. As a result, electrons generated by photoexcitation of the dye is sufficiently suppressed from being charged into the conduction band of the oxide semiconductor layer  13 . As a result, the change in the ratio of the redox pair in the electrolyte  40  is sufficiently suppressed, and durability of the photoelectric conversion element  100  is improved. In addition, according to the photoelectric conversion device  300 , in a case where the switching part  105  is controlled by the controlling part  106  so that the electric storage part  102  is charged by switching the switching part to the first state where the voltage output from the voltage conversion part  101  is applied only to the electric storage part  102  as well as in a case where the switching part  105  is controlled by the controlling part  106  so that the electric storage part  102  is discharged and a voltage is applied to the load part  103  by switching the switching part to the second state where the voltage output from the voltage conversion part  101  is not applied to any of the electric storage part  102  and the load part  103 , the photoelectric conversion element  100  is not short-circuited. Therefore, it is sufficiently suppressed that an excessive current is caused to flow in the photoelectric conversion element  100 . Accordingly, according to the photoelectric conversion device  300 , it is possible to prevent destruction of the photoelectric conversion element  100  and have excellent durability. In addition, as the switching part  305 , for example, a two-input one-output multiplexer load switch can be used. 
     In the above embodiments, in the photoelectric conversion element  100 , a second sealing portion  32 A is adhered to the first sealing portion  31 A. However, the second sealing portion  32 A may not be adhered to the first sealing portion  31 A. 
     Furthermore, in the above embodiments, the sealing portion  30 A includes the first sealing portion  31 A and the second sealing portion  32 A in the photoelectric conversion element  100 . However, the second sealing portion  32 A may be omitted. 
     Further, in the above embodiments, the groove  90  is formed in the transparent conductive layer  12  and the insulating material  33  enters the groove  90  in the photoelectric conversion element  100 . However, the insulating material  33  does not necessarily enter the groove  90 , and the groove  90  is not necessarily formed in the transparent conductive layer  12 . For example, in a case where the photoelectric conversion element  100  has only one photoelectric conversion cell, it is not necessary to form the groove  90  in the transparent conductive layer  12 . In this case, the insulating material  33  does not enter the groove  90 . 
     In the above embodiments, the back sheet  80  and the transparent conductive layer  12  are connected to each other via the coupling portion  14  in the photoelectric conversion element  100 . However, the back sheet  80  and the transparent conductive layer  12  are not necessarily adhered to each other via the coupling portion  14 . 
     In the embodiments, the photoelectric conversion element  100  includes the back sheet  80 . However, the photoelectric conversion element  100  does not necessarily have the back sheet  80 . 
     Further, in the above embodiments, the counter substrate  20  includes the conductive substrate  21  and the catalyst layer  22 . However, the counter substrate  20  may be composed of an insulating substrate. In this case, however, a counter electrode is provided on the oxide semiconductor layer  13 . A porous insulating layer is provided between the oxide semiconductor layer  13  and the counter electrode. The porous insulating layer is used mainly for impregnating the electrolyte  40  inside. As such a porous insulating layer, for example, a fired body of an oxide can be used. In addition, the porous insulating layer may be provided between the electrode substrate  10  and the counter electrode so as to surround the oxide semiconductor layer  13 . 
     Furthermore, in the above embodiments, a plurality of cells  50  are connected in series by the wiring materials  60 P in the photoelectric conversion element  100 , but they may be connected in parallel. 
     EXAMPLES 
     Hereinafter, one or more embodiments of the present invention will be described more specifically with reference to examples, the present invention is not limited to the following examples. 
     Example 1 
     First, a photoelectric conversion element was manufactured in the following manner. 
     First, a laminate obtained by forming a transparent conductive layer composed of FTO (Fluorine-doped Tin Oxide) having a thickness of 1 μm on a transparent substrate which is composed of glass and has a thickness of 1 mm was prepared. Next, as illustrated in FIG.  6 , the groove  90  was formed in the transparent conductive layer by a CO 2  laser (V-460 manufactured by Universal Laser Systems Inc.) to form the transparent conductive layers  12 A to  12 F. At this time, the width of the groove  90  was set to 1 mm. In addition, each of the transparent conductive layers  12 A to  12 C was formed so as to have the main body portion having a quadrangular shape of 4.6 cm×2.0 cm and the protruding portion protruding from the side edge portion of one side of the main body portion. In addition, the transparent conductive layer  12 D was formed so as to have the main body portion having a quadrangular shape of 4.6 cm×2.1 cm and the protruding portion protruding from the side edge portion of one side of the main body portion. In addition, the protruding portion  12   c  of the three transparent conductive layers  12 A to  12 C among the transparent conductive layers  12 A to  12 D was constituted by the projecting portion  12   d  projecting from the one side edge portion  12   b  of the main body portion  12   a  and the facing portion  12   e  which was extended from the projecting portion  12   d  and faced the main body portion  12   a  of the adjacent transparent conductive layer  12 . In addition, the protruding portion  12   c  of the transparent conductive layer  12 D was constituted only by only the projecting portion  12   d  projecting from the one side edge portion  12   b  of the main body portion  12   a . At this time, the length of the projecting direction (the direction orthogonal to the X direction in  FIG. 5 ) of the projecting portion  12   d  was set to 2.1 mm and the width of the projecting portion  12   d  was set to 9.8 mm. In addition, the width of the facing portion  12   e  was set to 2.1 mm and the length of the facing portion  12   e  in the extending direction was set to 9.8 mm. 
     In addition, the transparent conductive layer  12 D was formed so as to have not only the main body portion  12   a  and the protruding portion  12   c  but also the first current extracting portion  12   f  and the connecting portion  12   g  connecting the first current extracting portion  12   f  and the main body portion  12   a . The transparent conductive layer  12 E was formed so as to have the second current extracting portion  12   h . At this time, the width of the connecting portion  12   g  was set to 1.3 mm and the length thereof was set to 59 mm. In addition, when the resistance value of the connecting portion  12   g  was measured by a four probe method, it was 100Ω. 
     Next, a precursor of the connecting terminal  16  constituted by the wiring material connecting portion  16 A and the wiring material non-connecting portion  16 B was formed on the protruding portion  12   c  of the transparent conductive layers  12 A to  12 C. Specifically, the precursor of the connecting terminal  16  was formed such that a precursor of the wiring material connecting portion  16 A was provided on the facing portion  12   e  and a precursor of the wiring material non-connecting portion  16 B was provided on the projecting portion  12   d . At this time, the precursor of the wiring material non-connecting portion  16 B was formed so as to be narrower than the width of the wiring material connecting portion  16 A. The precursor of the connecting terminal  16  was formed by applying a silver paste (“GL-6000X16” manufactured by FUKUDA METAL FOIL &amp; POWDER Co., LTD.) by screen printing and drying it. 
     Furthermore, a precursor of the current collecting wiring  17  was formed on the connecting portion  12   g  of the transparent conductive layer  12 D. The precursor of the current collecting wiring  17  was formed by applying the silver paste by screen printing and drying it. 
     In addition, precursors of the external connecting terminals  18   a  and  18   b  for extracting the current to the outside were formed on the first current extracting portion  12   f  and the second current extracting portion  12   h  of the transparent conductive layer  12 A, respectively. The precursors of the external connecting terminals were formed by applying the silver paste by screen printing and drying it. 
     Moreover, a precursor of the insulating material  33  composed of a glass frit was formed so as to enter into the groove  90  and to cover the edge portion of the main body portion  12   a  forming the groove  90 . The insulating material  33  was formed by applying a paste containing a glass frit by screen printing and drying it. At this time, the edge portion of the transparent conductive layer covered with the insulating material  33  was the part between the groove  90  and the position 0.2 mm away from the groove  90 . 
     In addition, in order to fix the back sheet  80 , in the same manner as the insulating material  33 , a precursor of the ring-shaped coupling portion  14  composed of a glass frit was formed so as to surround the insulating material  33  and to pass through the transparent conductive layer  12 D, the transparent conductive layer  12 E, and the transparent conductive layer  12 F. In addition, at this time, the precursor of the coupling portion  14  was formed such that the precursor of the current collecting wiring  17  was disposed on the inner side thereof. In addition, the coupling portion  14  was formed such that the first current extracting portion and the second current extracting portion were disposed on the outer side thereof. The coupling portion  14  was formed by applying a paste containing a glass frit by screen printing and drying it. 
     Furthermore, a precursor of the oxide semiconductor layer  13  was formed on the main body portion  12   a  of each of the transparent conductive layers  12 A to  12 D. At this time, the precursor of the oxide semiconductor layer  13  was obtained by applying a nanoparticle paste of a titanium oxide for forming a light absorbing layer containing an anatase crystalline titanium oxide (21NR manufactured by JGC Catalysts and Chemicals Ltd.) in a square shape by screen printing and drying it at 150° C. for 10 minutes. 
     Next, the precursor of the connecting terminal  16 , the precursor of the current collecting wiring  17 , the precursors of the external connecting terminals  18   a  and  18   b , the precursor of the insulating material  33 , the precursor of the coupling portion  14 , the precursor of the insulating material  33 , and the precursor of the oxide semiconductor layer  13  were fired at 500° C. for 15 minutes to form the connecting terminal  16 , the current collecting wiring  17 , the external connecting terminals  18   a  and  18   b , the coupling portion  14 , the insulating material  33 , and the oxide semiconductor layer  13 . In this manner, the electrode substrate  10  on which the oxide semiconductor layer  13 , the coupling portion  14 , the current collecting wiring  17  and the external connecting terminals  18   a ,  18   b  were formed. At this time, the width of the wiring material connecting portion of the connecting portion  16  was 1.0 mm and the width of the wiring material non-connecting portion thereof was 0.3 mm. In addition, the length along the extending direction of the wiring material connecting portion was 7.0 mm and the length along the extending direction of the wiring material non-connecting portion was 7.0 mm. In addition, the dimensions of the current collecting wiring  17 , the external connecting terminals  18   a  and  18   b , the coupling portion  14 , and the oxide semiconductor layer  13  were as follows, respectively. 
     Current collecting wiring  17 : 4 μm in thickness, 200 μm in width, 79 mm in length along the X direction in  FIG. 5 , and 21 mm in length along the direction orthogonal to the X direction in  FIG. 5 ,
 
External connecting terminals  18   a  and  18   b:  20 μm in thickness, 2 μm in width, and 7 mm in length,
 
Coupling portion  14 : 50 μm in thickness, 3 mm in width, and Oxide semiconductor layer  13 : 14 μm in thickness, 17 mm in length in the X direction in  FIG. 5 , and 42.1 mm in length in the direction orthogonal to the X direction in  FIG. 5 
 
     Thus, the working electrode was obtained. 
     Next, the working electrode obtained in the above-described manner was immersed for a whole day and night in a dye solution containing 0.2 mM of a photosensitizing dye consisting of N719 and a mixed solvent prepared by mixing acetonitrile and tert-butanol at a volume ratio of 1:1 as the solvent, and then taken out therefrom and dried, and thus the photosensitizing dye was supported on the oxide semiconductor layer. 
     Next, an electrolyte obtained by adding I 2 , methyl benzimidazole, butyl benzimidazole, guanidium thiocyanate, and t-butylpyridine to a mixture of dimethyl propyl imidazolium iodide and 3-methoxy propionitrile was applied on the oxide semiconductor layer by a screen printing method and drying was performed. Thus, the electrolyte was arranged. 
     Next, the first integrated sealing portion forming body for forming the first sealing portion was prepared. The first integrated sealing portion forming body was obtained by preparing one sheet of resin film for sealing which had 8.0 cm×4.6 cm×50 μm and was composed of a maleic anhydride-modified polyethylene (product name: Bynel produced by DuPont) and forming four quadrangular-shaped openings in the resin film for sealing. At this time, the first integrated sealing portion forming body was fabricated such that each opening had a size of 1.7 cm×4.4 cm×50 μm, the width of the ring-shaped outer peripheral portion was 2 mm, and the width of the partitioning portion partitioning the inner opening of the ring-shaped outer peripheral portion was 2.6 mm. 
     Thereafter, the first integrated sealing portion forming body was superimposed on the insulating material  33  on the working electrode and then the first integrated sealing portion forming body was adhered to the insulating material  33  on the working electrode by heating to melt. 
     Next, four sheets of the counter electrodes were prepared. Two counter electrodes of the four sheets of the counter electrodes were prepared by forming the catalyst layer which had a thickness of 5 nm and was composed of platinum on the titanium foil of 4.6 cm×1.9 cm×40 μm by a sputtering method. The remaining two counter electrodes of the four sheets of the counter electrodes were prepared by forming the catalyst layer which had a thickness of 5 nm and was composed of platinum on the titanium foil of 4.6 cm×2.0 cm×40 μm by the sputtering method. In addition, another first integrated sealing portion forming body was prepared and this first integrated sealing portion forming body was adhered to the surface of the counter electrode facing the working electrode in the same manner as above. 
     Thereafter, the first integrated sealing portion forming body adhered to the working electrode was allowed to face the first integrated sealing portion forming body adhered to the counter electrode, and thus the first integrated sealing portion forming bodies were superimposed on each other. The first integrated sealing portion forming bodies were then melted by heating while being pressurized in this state. The first sealing portion was thus formed between the working electrode and the counter electrode. 
     Next, the second integrated sealing portion was prepared. The second integrated sealing portion was obtained by preparing one sheet of resin film for sealing which had 8.0 cm×4.6 cm×50 μm and was composed of maleic anhydride modified polyethylene (trade name: Bynel, manufactured by Du Pont) and forming four quadrangular-shaped openings in the resin film for sealing. At this time, the second integrated sealing portion was fabricated such that each opening had a size of 1.7 cm×4.4 cm×50 μm, the width of the ring-shaped outer peripheral portion was 2 mm, and the width of the partitioning portion partitioning the inner opening of the ring-shaped outer peripheral portion was 2.6 mm. The second integrated sealing portion was bonded to the counter electrode so as to sandwich the edge portion of the counter electrode together with the first integrated sealing portion. At this time, the second integrated sealing portion was bonded to the counter electrode and the first integrated sealing portion by heating the first integrated sealing portion and the second integrated sealing portion to melt while being pressed to the counter electrode. 
     Next, the desiccant sheet was bonded on the metal substrate of each counter electrode with a double-sided tape. The dimensions of the desiccant sheet were 1 mm in thickness×3 cm in length×1 cm in width, and Zeosheet (trade name, manufactured by Shinagawa Chemicals Co., Ltd.) was used as the desiccant sheet. 
     Next, silver particles (average particle diameter: 3.5 μm), carbon (average particle diameter: 500 nm) and a polyester-based resin were dispersed in diethylene glycol monoethyl ether acetate which is a solvent to fabricate a first conductive paste. At this time, the silver particles, carbon, the polyester-based resin and the solvent were mixed in a mass ratio of 70:1:10:19. Then, this first conductive paste was coated on each of the conductive substrates  21  of the cells  50 A to  50 D so as to have dimensions of 2 mm×2 mm×50 μm and temporarily dried at 85° C. for 10 minutes. A precursor of the first connecting portion was thus obtained. 
     On the other hand, silver particles (average particle diameter: 2 μm) and a polyester-based resin were dispersed in ethylene glycol monobutyl ether to fabricate a second conductive paste. At this time, the silver particles, the polyester-based resin, and the solvent were mixed at a mass ratio of 65:10:25. 
     Then, the second conductive paste was coated so as to connect the wiring material connecting portions on the four transparent conductive layers  12 A to  12 C and  12 E with the precursor of the first connecting portion formed on each of the conductive substrates  21  of the cells  50 A to  50 D, respectively, and cured to form the wiring material  60 P having a width of 2 mm. At this time, the wiring material  60 P was formed by curing the second conductive paste at 85° C. for 12 hours. 
     Then, as illustrated in  FIG. 5 , the bypass diodes  70 A to  70 D were disposed on the second integrated sealing portion, and the wiring material  60 Q having a width of 2 mm was formed on the conductive substrate  21  of the counter electrode so as to connect each of the bypass diodes  70 A to  70 D with the precursor of the first connecting portion of each of the cells  50 A to  50 D. The wiring material  60 Q was formed by coating the second conductive paste and curing it through a heat treatment at 85° C. for 12 hours. At this time, the first connecting portion was obtained from the precursor of the first connecting portion. As the bypass diodes  70 A to  70 D, the RB751V-40 manufactured by ROHM Co., Ltd. was used. 
     Next, the butyl rubber (“Aikameruto” manufactured by Aica Kogyo Co., Ltd.) was coated on the coupling portion  14  with a dispenser while being heated at 200° C. On the other hand, a laminate, which was obtained by laminating a polybutylene terephthalate (PBT) resin film (50 μm in thickness), aluminum foil (25 μm in thickness), and a film (50 μm in thickness) composed of Bynel (trade name, manufactured by Du Pont) in this order, was prepared. Then, the peripheral portion of this laminate was superimposed on the butyl rubber, and was pressurized for 10 seconds. In this manner, the back sheet  80  constituted by the laminate was obtained on the coupling portion  14 . The photoelectric conversion element was obtained in the manner described above. 
     Next, a photoelectric conversion device was manufactured so as to constitute a circuit illustrated in  FIG. 1 , using the photoelectric conversion element  100  obtained as described above. At this time, in the photoelectric conversion element  100 , the first external output terminal  18   a  was used as a terminal on the positive electrode side, and the second external output terminal  18   b  was used as a terminal on the negative electrode side. 
     As the voltage conversion part  101 , the electric storage part  102 , the load part  103 , the voltage monitoring part  104 , the first switching element  105   a , the second switching element  105   b , and the controlling part  106 , the followings were used, respectively. At this time, as the controlling part  106 , the controlling part was used which applies a potential of 3.0 V to the gates of the first switching element  105   a  and the second switching element  105   b  when the voltage of the storage part  102  reaches the full charge voltage, applies a potential of 0 V to the gates of the first switching element  105   a  and the second switching element  105   b  when the voltage of the electric storage part  102  becomes less than the full charge voltage. 
     Voltage conversion part  101 : DC/DC converter (product name: “dq25570”, manufactured by Texas Instruments Inc. output voltage after boosting: 3.0 V)
 
Electric storage part  102 : coin type manganese lithium secondary battery (product name “ML2430”, manufactured by FDK CORPORATION, full charge voltage: 3.0 V)
 
Load part  103 : a resistance element having a resistance of 30Ω
 
Voltage monitoring part  104  and controlling part  106 : a voltage detector (product name “S-1009 series”, manufactured by SII semiconductor Corporation)
 
The first switching element  105   a : p-channel MOSFET (ON when the potential of 0 V is applied to the gate, OFF when the potential of 3.0 V is applied to the gate)
 
The second switching element  105   b : n-channel MOSFET (ON when the potential of 3.0 V is applied to the gate, OFF when the potential of 0 V is applied to the gate)
 
     Comparative Example 1 
     A photoelectric conversion device was manufactured in the same manner as Example 1 except that the load part  103 , the voltage monitoring part  104 , the first switching element  105   a , the second switching element  105   b  and the controlling part  106  were not incorporated when forming a circuit. 
     [Characteristic Evaluation] 
     With respect to the photoelectric conversion devices of Example 1 and Comparative Example 1 obtained as described above, durability was evaluated in the following manner. 
     With respect to the photoelectric conversion devices of Example 1 and Comparative Example 1, an IV curve was measured in a state in which white light of 200 lux was irradiated, and the maximum output operating power (μW) was calculated from the IV curve as “P 1 ”. 
     Subsequently, a fluorescent lamp of 500 lux is continuously irradiated to the photoelectric conversion elements of the photoelectric conversion devices of Example 1 and Comparative Example 1 for 1,000 hours, and then an IV curve was measured in a state in which white light of 200 lux was irradiated. The maximum output operating power (μW) was calculated from the IV curve as “P 2 ”. 
     Then, the output retention rate was calculated on the basis of the following expression, and this was used as an index of durability. The results are illustrated in Table 1. 
       Output retention rate (%)=100× P 2/ P 1
 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Presence or 
                   
               
               
                   
                   
                 Absence of 
                 Durability 
               
               
                   
                   
                 Volatage 
                 Output 
               
               
                   
                 Presence or 
                 monitoring part 
                 Retention 
               
               
                   
                 Absence of 
                 and controlling 
                 Rate 
               
               
                   
                 Swithing part 
                 part 
                 (%) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Example 1 
                 Present 
                 Present 
                 98 
               
               
                   
                 Comparative 
                 Absent 
                 Absent 
                 70 
               
               
                   
                 Example 1 
               
               
                   
                   
               
            
           
         
       
     
     As illustrated in Table 1, it was found that in Example 1 the output retention rate of the photoelectric conversion element was greater than the output retention rate of the photoelectric conversion element of Comparative Example 1. In addition, it was found that in Example 1 the photoelectric conversion element was not broken. 
     From the above, it was confirmed that according to the photoelectric conversion device of one or more embodiments of the present invention, it is possible to prevent destruction of a photoelectric conversion element and have excellent durability. 
     EXPLANATIONS OF LETTERS OR NUMERALS 
     
         
         
           
               10  Electrode substrate 
               13  Oxide semiconductor layer 
               20  Counter substrate 
               50 ,  50 A- 50 D Photoelectric conversion cell 
               100  Photoelectric conversion element 
               101  Voltage conversion part 
               102  Electric storage part 
               103  Load part 
               104  Voltage monitoring part 
               105 ,  305  Switching part 
               105   a  First switching element 
               105   b  Second switching element 
               106  Controlling part 
               200 ,  300  Photoelectric conversion device 
             G gate (first gate electrode, second gate electrode) 
           
         
       
    
     Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.