JP5288557B2 - Evaluation method, evaluation apparatus and manufacturing method of thin film solar cell, and evaluation method and evaluation apparatus of series resistance in transparent conductive film electrode - Google Patents

Description

  The present invention relates to an evaluation method and an evaluation apparatus for evaluating the performance of a thin film solar cell, and particularly to an evaluation method and an evaluation apparatus for evaluating the series resistance of a thin film solar cell.

  In recent years, thin-film solar cells are expected as next-generation devices that can realize large-area and low-cost solar cells, and development of technology for improving the conversion efficiency of thin-film solar cells is being promoted for further popularization .

  In general, in order to improve the conversion efficiency of a solar cell, it is necessary to mainly consider the performance of a semiconductor layer that receives sunlight to generate power and an electrode (particularly a series resistance component) through which a current generated in the semiconductor layer flows. is there. For example, a semiconductor layer that can receive more sunlight, a semiconductor layer that can generate current more efficiently, and a material and shape design for electrodes that have a series resistance component with low energy loss (low resistance) Development is proceeding from such a viewpoint.

  Here, the basic structure of the thin film solar cell will be described with reference to FIG. FIG. 2A is a schematic diagram showing an example of the structure of a super straight type thin film solar cell. As illustrated, in the thin film solar cell 7, the semiconductor layer 33 that is a photoelectric conversion layer receives sunlight 36 that has passed through the glass substrate 31 and the upper transparent conductive film electrode 32. The current generated in the semiconductor layer 33 (white arrow A in the figure) is taken out via the lower metal electrode 34 and the upper transparent conductive film electrode 32 (black arrow A 'in the figure).

  As described above, the upper transparent conductive film electrode 32 must not only pass the current generated in the semiconductor layer 33 but also transmit sunlight. In order to efficiently transmit sunlight, the upper transparent conductive film electrode 32 is made of a transparent material that allows sunlight to pass through, and its shape must be as thin as possible. Therefore, the upper transparent conductive film electrode 32 is limited in terms of material and shape design, and as a result, the resistance value becomes larger than the lower electrode made of metal or the like.

  That is, in the case of a thin-film solar cell, the influence of the series resistance component of the electrode on the power generation efficiency of the thin-film solar cell is greater for structural reasons than a conventional crystalline solar cell. Therefore, in developing a thin film solar cell, it is important to accurately grasp and evaluate the series resistance component of the transparent conductive film electrode.

  Conventionally, various techniques for evaluating the series resistance component of a transparent conductive film electrode include, for example, the resistance of a transparent conductive film electrode in a state where the transparent conductive film electrode is deposited on a glass substrate during the production of a thin film solar cell element. There are methods for direct measurement and evaluation.

  Moreover, the technique of a nonpatent literature 1 is reported as an evaluation technique of the series resistance component of a crystal-type element instead of a thin film solar cell element. In this Non-Patent Document 1, a voltage is applied to a single crystal silicon element, the intensity of light emitted from the element and the value obtained by differentiating the intensity with respect to the voltage are analyzed, and the resistance value of the series resistance is calculated. A method for calculating is disclosed.

David Hinken, et. Al., “SERIES RESISTANCE IMAGING OF SOLAR CELLS BY VOLTAGE DEPENDENT ELCTROLUMINESCENCE” Technical Digest of the International PVSEC-17, Fukuoka, Japan, 5O-M3-04, 2007

  The evaluation of the series resistance component of the thin film solar cell is desirably performed in a commercialized state. However, the technique for directly measuring the resistance of the transparent conductive film electrode as described above is difficult to apply to a commercialized thin film solar cell. The technique of Non-Patent Document 1 is a method for evaluating the resistance component of the emitter layer (n-type or p-type semiconductor layer) of a crystalline silicon element, and cannot be applied to a thin film element. Therefore, development of the technique which can evaluate the resistance component of the transparent conductive film electrode of a thin film solar cell was strongly calculated | required even if it was a commercialized state.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to evaluate a series resistance component of a thin film solar cell, particularly a series resistance component of a transparent conductive film electrode of a thin film solar cell. To realize a method and an evaluation apparatus.

  As a result of diligent research in view of the above problems, the present inventors have found that when the current is conducted in the forward direction with respect to the thin film solar cell element, there is a variation in the emission intensity of the thin film solar cell element. It was found that the intensity variation was caused by energy loss in the series resistance component of the thin film solar cell element. Based on this knowledge, the present inventors can introduce a current into a thin-film solar cell element to emit light, and can easily evaluate the series resistance of the thin-film solar cell element using the emission intensity as an index. It came to complete. That is, this invention includes the following invention as an industrially useful method or its utilization.

  An evaluation method according to the present invention is an evaluation method for a thin-film solar cell that evaluates the performance of the thin-film solar cell in order to solve the above-described problems, and is in order with respect to the thin-film solar cell element constituting the thin-film solar cell. A current introduction step for introducing a direct current in the direction, a light emission intensity measurement step for measuring light emission intensity of light generated from the thin film solar cell element by the current introduction step, and the light emission intensity measured by the light emission intensity measurement step. And a change amount calculating step of calculating a change amount with respect to the lateral distance of the thin film solar cell element.

  Moreover, in order to solve the said subject, the evaluation apparatus which concerns on this invention is an evaluation apparatus of the thin film solar cell which performs the performance evaluation of a thin film solar cell, Comprising: With respect to the thin film solar cell element which comprises the said thin film solar cell A current introduction means for introducing a direct current in a forward direction, a light emission intensity measurement means for measuring the light emission intensity of light generated from the thin film solar cell element by the direct current introduced by the current introduction means, and the light emission intensity measurement means And a change amount calculating means for calculating a change amount with respect to a lateral distance of the thin film solar cell element.

  The evaluation method according to the present invention further determines that the series resistance value is large when the amount of change calculated in the change amount calculating step is larger than a predetermined value, and series when it is smaller than the predetermined value. It is preferable to include a resistance value determination step for determining that the resistance value is small.

  Further, the evaluation device according to the present invention further determines that the series resistance value is large when the change amount calculated by the change amount calculation means is larger than a predetermined value, and series when it is smaller than the predetermined value. It is preferable to include a resistance value determining unit that determines that the resistance value is small.

  Moreover, it is preferable that the evaluation method according to the present invention further includes a resistance value calculation step of calculating a series resistance value of the thin-film solar cell based on the change amount calculated in the change amount calculation step.

  Moreover, it is preferable that the evaluation apparatus according to the present invention further includes resistance value calculation means for calculating a series resistance value of the thin-film solar cell based on the change amount calculated by the change amount calculation means.

  The evaluation method according to the present invention introduces a direct current in the forward direction with respect to the thin film solar cell element at a plurality of predetermined current values in which the current value of the direct current is arbitrarily set in the current introduction step. In the emission intensity measurement step, the emission intensity corresponding to the plurality of predetermined current values is measured, and in the change amount calculation step, the measured emission intensity is measured in the lateral direction of the thin-film solar cell element. The amount of change with respect to each distance is calculated, and for each of the obtained calculation results, it is determined whether the amount of change is substantially zero, and the current value corresponding to the amount of change determined to be substantially zero is determined. It is preferable to include a current value specifying step of specifying.

  Further, in the evaluation apparatus according to the present invention, the current introduction means introduces a direct current in a forward direction with respect to the thin-film solar cell element at a plurality of predetermined current values in which a direct current value is arbitrarily set. The emission intensity measuring means measures emission intensity corresponding to the plurality of predetermined current values, and the change amount calculating means includes the emission intensity measured by the emission intensity measuring means. For each of the above-mentioned thin film solar cell elements to calculate the amount of change with respect to the distance in the lateral direction, and further determine whether the amount of change is substantially zero for the obtained plurality of calculation results, It is preferable to include a current value specifying means for specifying a current value corresponding to the change amount determined to be zero.

  Further, the evaluation method according to the present invention further includes an operating current determination for determining the largest current value among the current values specified by the current value specifying step as the current value of the operating current of the thin-film solar cell element. It is preferable to include a process.

  The evaluation apparatus according to the present invention further includes an operating current determining unit that determines the largest current value as the current value of the operating current of the thin-film solar cell element from the current values specified by the current value specifying unit. It is preferable to provide.

  Moreover, it is preferable that the serial resistance evaluation method in the transparent conductive film electrode which concerns on this invention evaluates the serial resistance of the transparent conductive film electrode in a thin film solar cell element using the said evaluation method of a thin film solar cell element.

  Moreover, the evaluation apparatus of the series resistance in the transparent conductive film electrode which concerns on this invention is equipped with the evaluation apparatus of the said thin film solar cell element, Furthermore, based on the result of the said evaluation apparatus, the evaluation means which evaluates the serial resistance in a transparent conductive film electrode It is preferable to provide.

  Moreover, it is preferable that the manufacturing method which concerns on this invention contains said evaluation method of a thin film solar cell as 1 process.

  The evaluation apparatus may be realized by a computer. In this case, a control program for causing the evaluation apparatus to be realized by the computer by operating the computer as each means of the evaluation apparatus, and recording the program. Such computer-readable recording media also fall within the scope of the present invention.

  According to the evaluation method or the evaluation apparatus according to the present invention, the series resistance component of the thin film solar cell, particularly the series resistance component of the transparent conductive film electrode of the thin film solar cell can be evaluated. In particular, evaluation is possible even when the thin film solar cell is in a commercialized state. Therefore, it is useful for the development of thin film solar cells.

  Other objects, features and advantages of the present invention will be fully understood from the following description. The benefits of the present invention will become apparent from the following description with reference to the accompanying drawings.

It is a functional block diagram which shows the principal part structure of an evaluation apparatus. It is a schematic diagram which shows an example of the structure of a super straight type thin film solar cell, (a) is a figure which shows the direction of the electric current which generate | occur | produces when irradiating sunlight to a thin film solar cell, (b) It is a figure which shows the direction of the electric current injected in order to make it light-emit from a thin film solar cell. It is a figure which shows one Embodiment of the evaluation apparatus of the thin film solar cell which concerns on this invention. It is a flowchart which shows the process of the evaluation apparatus regarding calculation of variation | change_quantity, and determination / calculation of resistance value. It is a flowchart which shows the process of the evaluation apparatus regarding specification of an electric current value, and determination of an operating current. (A) is an image in which the emission intensity measurement unit 12 images a thin film solar cell that emits light when a voltage of 8.6 V is applied to the thin film solar cell so that a direct current of 200 mA flows in the forward direction. FIG. (B) and (c) are graphs showing the emission intensity measured by the emission intensity measuring unit 12 when DC currents of 200 mA and 50 mA are respectively introduced in the forward direction with respect to the thin-film solar cell (sample number: J24). FIG. It is a figure which shows the result of having measured the light emission intensity of "Top" and "Bottom" in each electric current value. It is a figure which shows the measurement result of the emission spectrum of a thin film solar cell. (A)-(c) is a figure which shows the image which the light emission intensity | strength measurement part when the electric current of 20 mA, 30 mA, and 80 mA was introduce | transduced into the thin film solar cell, respectively image | photographed the thin film solar cell. (D)-(f) is a figure which shows the graph of the emitted light intensity which the emitted light intensity measurement part measured when the electric current of 20 mA, 30 mA, and 80 mA was introduce | transduced into the thin film solar cell, respectively.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  First, a basic structure of a thin film solar cell common to both methods and apparatuses will be described with reference to FIG. The thin film solar cell 7 shown in FIG. 2 is an example in which three thin film solar cell elements 7a are connected. As illustrated, the thin film solar cell 7 includes a glass substrate 31, an upper transparent conductive film electrode 32, a semiconductor layer 33, and a lower metal electrode 34. The semiconductor layer 33 is a photoelectric conversion layer, and is formed of, for example, single crystal silicon, amorphous silicon, polycrystalline silicon, or the like. The lower metal electrode 34 is an electrode for supplying the current generated in the semiconductor layer 33 to the outside, and is formed of a metal such as aluminum or silver, for example. The upper transparent conductive film electrode 32 is an electrode for supplying the current generated in the semiconductor layer 33 to the outside, and is formed of, for example, an ITO (indium tin oxide) film. The upper transparent conductive film electrode 32 is connected to an external supply terminal (not shown).

  FIG. 2A is a diagram illustrating the direction of current generated when the thin film solar cell 7 is irradiated with sunlight 36. In the thin film solar cell 7 shown to Fig.2 (a), the sunlight 36 is irradiated from the glass substrate 31 side. When the sunlight 36 is applied to the thin film solar cell 7, the semiconductor layer 33 receives the sunlight 36 that has passed through the glass substrate 31 and the upper transparent conductive film electrode 32. In the semiconductor layer 33, a current (white arrow A in the figure) is generated according to the received sunlight 36, and the current generated in the semiconductor layer 33 passes through the lower metal electrode 34 and the upper transparent conductive film electrode 32. To the outside (black arrow A ′ in the figure).

  Next, the state when the current is injected into the thin film solar cell 7 when the performance and the like of the thin film solar cell 7 are evaluated will be described with reference to FIG. FIG. 2B is a diagram showing the direction of the current injected to emit light 35 from the thin-film solar cell 7. The direction of the injected current is opposite to the current generated when the thin film solar cell 7 is irradiated with sunlight. In the example shown in FIG. 2B, the current is injected from the right side of the thin film solar cell 7. As shown in the figure, the injected current flows from the lower metal electrode 34 to the upper transparent conductive film electrode 32 (black arrow I ′ in the figure), the semiconductor layer 33 (white arrow I in the figure), and the lower metal. It flows from the electrode 34 to the upper transparent conductive film electrode 32.

  Thus, when a current flows through the semiconductor layer 33, the semiconductor layer 33 emits light, and light 35 is irradiated from the thin film solar cell 7. When a current is injected into the thin-film solar cell 7, the performance of the thin-film solar cell 7 is evaluated by measuring the light 35 emitted from the thin-film solar cell 7 with a camera or the like.

  In addition, when a thin film solar cell element is irradiated with sunlight, a current that is actually generated by photoelectric conversion is referred to as an operating current. The value of this operating current can be changed as appropriate according to the material and composition of the thin-film solar cell element. The reverse direction in which the operating current flows through the thin-film solar cell 7 is referred to as the forward direction. A bias is applied to the so-called thin film solar cell 7 in order to inject a direct current in the forward direction. By applying an external voltage of positive (+) polarity to the p-type region side of the pn junction of the semiconductor layer 33 in the thin-film solar cell element 7a constituting the thin-film solar cell 7 and negative (-) polarity to the n-type region side, A direct current is introduced in the forward direction. For example, in the example shown in FIG. 2B, the directions of the black arrow I 'and the white arrow I are the forward directions. Further, as indicated by the black arrow I ′ in FIG. 2B, the direction in which current flows from the end portion 32a to the end portion 32b of the upper transparent conductive film electrode 32 is defined as the horizontal direction. That is, the “lateral direction of the thin film solar cell element” means a direction in which a current generated when the thin film solar cell element 7 is irradiated with light flows through the upper transparent conductive film electrode 32 (an operating current is the upper transparent conductive film electrode 32). Direction opposite to the direction of flow).

  Hereinafter, the performance of the thin film solar cell described above, in particular, the evaluation method and the evaluation device for the series resistance component will be described in detail.

<1. Evaluation Method for Thin Film Solar Cell>
The evaluation method of a thin film solar cell according to the present invention is a solar cell evaluation method for evaluating the performance of a thin film solar cell, and at least direct current in the forward direction with respect to the thin film solar cell element constituting the thin film solar cell. About the current introduction step for introducing current, the emission intensity measurement step for measuring the emission intensity of light generated from the thin film solar cell element by the current introduction step, and the emission intensity measured by the emission intensity measurement step, Any method that includes a change amount calculating step of calculating a change amount with respect to the lateral distance of the thin film solar cell element may be used. In addition, specific processes other than the above processes, materials, conditions, devices and apparatuses to be used, etc. are not particularly limited, and conventionally known methods can be suitably used.

  Here, in the present specification, the term “performance evaluation” means performance evaluation of a photoconductive effect and / or a photovoltaic effect in a thin film solar cell module and a thin film solar cell element which is a constituent member thereof.

  In addition, in this specification, the term “thin film solar cell” means not only the super-straight type thin film solar cell described above, but also other conventionally known components within a reasonable range capable of achieving the effects of the present invention.・ Includes thin film solar cells of materials and structures. The “thin film solar cell element” means a minimum structural unit that generates light by receiving light by a photoconductive effect and / or a photovoltaic effect, and includes, for example, a strip-shaped element of 5 mm × 10 cm. As an integrated type of thin film solar cell elements, there is one having a size of 10 cm × 10 cm composed of 20 thin film solar cell elements. Further, the “thin film solar cell module” refers to a structure in which a plurality of the thin film solar cell elements are connected, for example, a 30 cm × 30 cm square structure in which 180 thin film solar cell elements are connected. be able to. In the present specification, the “thin film solar cell module” includes a “thin film solar cell panel” which is an assembly of modules. In addition, when simply referred to as “thin film solar cell”, it represents any one or all of a thin film solar cell element, a thin film solar cell module, and a thin film solar cell panel.

  Hereinafter, each step of the method according to the present invention will be described in detail.

<1-1. Current introduction process>
The current introduction step may be a step of introducing a direct current in the forward direction with respect to the thin film solar cell element constituting the thin film solar cell, and other specific methods, equipment, conditions, and the like are not particularly limited.

  In the current introduction step, “introducing a direct current in the forward direction” means applying a bias to the thin film solar cell 7 in order to inject a direct current in the forward direction. As a method for injecting current, for example, as shown in FIG. 2 described later, there is a method in which electrodes are connected to both ends of the thin film solar cell 7 and a current is injected into the thin film solar cell 7 by applying a bias between both electrodes. It is done. In addition, the lower metal electrode 34 and the upper transparent conductive film are applied so that an external voltage having a positive (+) polarity is applied to the p-type region side of the semiconductor layer 33 and a negative (−) polarity is applied to the n-type region side of the semiconductor layer 33. A method of introducing a direct current by applying a bias to the electrode 32 may be used.

  In this step, as a device for conducting current to the thin-film solar cell element, a conventionally known power source or the like can be suitably used, and is not particularly limited. A current source can be used.

<1-2. Emission intensity measurement process>
The light emission intensity measurement step may be a step of measuring the light emission intensity of light generated from the thin film solar cell element by the current introduction step, and other specific methods, equipment, conditions, and the like are not particularly limited.

  In the light emission intensity measurement step, a conventionally known light detection means capable of measuring the light emission intensity of light from the thin film solar cell element can be used, and the specific configuration thereof is not particularly limited. For example, a conventionally known photodetector such as a CCD camera can be used. Examples of the CCD camera include an InGaAs CCD camera (manufactured by Xenics, product number XEVA-1.7 series), a Si CCD camera (manufactured by Hamamatsu Photonics, product number C9299-02), and the like.

  In the emission intensity measurement step, it is preferable to measure light having a wavelength of about 800 nm to 1600 nm, and it is more preferable to measure light having a wavelength of about 1000 nm to 1400 nm. By measuring light in such a wavelength region, the emission intensity associated with the series resistance component can be accurately measured.

  When light is detected using such a photodetector such as a CCD camera, the state of light emission in the solar cell can be observed as an image. That is, the in-plane distribution of light emission in the thin film solar cell can be collectively measured two-dimensionally, and can be evaluated easily and quickly over the entire surface of the thin film solar cell module.

  That is, the specific method for the emission intensity measurement step is not particularly limited, and a conventionally known technique can be suitably used.

<1-3. Change calculation process>
The change amount calculation step may be a step of calculating the change amount with respect to the lateral distance of the thin film solar cell element with respect to the light emission intensity measured in the light emission intensity measurement step. Can be suitably used. For example, as a specific calculation in the change amount calculation step, a differential value of the light emission intensity with respect to the lateral distance of the light emission intensity may be calculated. In addition, a graph may be created with the emission intensity as the vertical axis and the horizontal distance of the solar cell element as the horizontal axis, and the inclination itself may be used as the change amount, or the change amount may be calculated from the inclination.

  The “lateral distance of the thin film solar cell element (lateral distance)” is the distance in the thin film solar cell element with the horizontal axis being positive. In other words, it means the distance between any two points on the horizontal axis in the thin film solar cell element. For example, the distance is from the end 32a to the end 32b of the upper transparent conductive film electrode 32 shown in FIG.

  As described above, when the current is conducted to the thin-film solar cell element, the present inventors have a uniform emission intensity in the thin-film solar cell element, and the emission intensity at the current injection point is the largest, It was found that the emission intensity was attenuated according to the lateral distance from the injection point. From this, it is considered that the current introduced into the thin film solar cell element decreases according to the distance in the lateral direction, and the cause is the series resistance component of the thin film solar cell, particularly the series resistance component of the transparent conductive film electrode of the thin film solar cell. It was inferred that this was due to energy loss. That is, in the thin film solar cell, the resistance value of the series resistance component of the transparent conductive film electrode increases according to the lateral distance from the injection point, and the energy loss due to the resistance increases as the lateral distance increases. It was considered that the voltage and current decreased with the distance.

  Therefore, the present inventors have determined the degree of attenuation of the emission intensity in the thin film solar cell element, that is, the amount of change in the emission intensity from the current injection point to the other end, and the series resistance component of the thin film solar cell, particularly the thin film solar cell. The resistance value of the series resistance component of the transparent conductive film electrode is considered to be closely related, and by calculating the amount of change in the emission intensity, the series resistance component of the thin film solar cell, particularly the transparent conductive film of the thin film solar cell The present invention of determining and / or calculating the resistance value (series resistance value) of the series resistance component of the electrode has been completed.

  That is, according to the thin film solar cell evaluation method of the present invention, in the current introduction step, a direct current is introduced into the thin film solar cell element constituting the thin film solar cell. In the emission intensity measurement step, the emission intensity of light generated from the thin film solar cell element is measured by the direct current introduced in the current introduction step. In the change amount calculation step, the change amount with respect to the lateral distance of the thin-film solar cell element is calculated for the light emission intensity measured in the light emission intensity measurement step. Therefore, the series resistance component of the thin film solar cell can be evaluated based on the calculated change amount.

  Further, according to the method for evaluating a thin film solar cell according to the present invention, in the case of a thin film solar cell module in which a plurality of thin film solar cell elements are connected in series, the entire thin film solar cell module is introduced by a single current introduction. Performance evaluation can be performed. That is, if current introduction is executed once, current flows through all the thin film solar cell elements constituting the thin film solar cell module, and thus all the thin film solar cell elements emit light. In this case, in the present invention, instantaneous batch measurement of the luminescence in-plane distribution can be performed. Specifically, for example, two-dimensional batch using a CCD or the like, and large area correspondence using a one-dimensional line scanner can be exemplified, but the invention is not limited to this. That is, if the emission intensity of the entire thin-film solar cell module is detected at once by a large emission intensity measuring means or a one-dimensional scanning line scanner, the emission intensity of all thin-film solar cell elements constituting the thin-film solar cell module is instantaneously determined. And can be evaluated very simply. Of course, it is also possible to measure the light emission intensity of a single thin film solar cell element or a specific position of the thin film solar cell module by using a small light emission intensity measuring means.

  Moreover, according to the evaluation method of the series resistance of the transparent conductive film electrode which concerns on this invention, the serial resistance of the transparent conductive film electrode in a thin film solar cell element is evaluated using the said evaluation method of a thin film solar cell element. Therefore, the series resistance of the transparent conductive film electrode in the thin film solar cell element can be evaluated based on the evaluated series resistance component of the thin film solar cell.

<1-4. Resistance value determination process>
Furthermore, in the method for evaluating a thin film solar cell according to the present invention, when the amount of change calculated in the change amount calculating step is larger than a predetermined value, it is determined that the series resistance value is large, and when the amount of change is smaller than the predetermined value. Preferably includes a resistance value determining step for determining that the series resistance value is small. As a specific method of the resistance value determination step, a conventionally known technique can be suitably used.

  Here, the “predetermined value” can include, for example, the amount of change in the thin film solar cell of the standard sample calculated in advance (or afterwards) by the evaluation method according to the present invention. In addition, what kind of thin film solar cell is used as the “standard sample” can be arbitrarily set, and is not particularly limited.

  In the method for evaluating a thin film solar cell according to the present invention, by performing the resistance value determination step, the resistance value of the series resistance component of the thin film solar cell to be evaluated is larger or smaller than that of the thin film solar cell to be compared. Can be determined. Therefore, by feeding back the determination result to the manufacturing process of the thin film solar cell element, it is possible to stably manufacture a thin film solar cell element having an element performance equivalent to or higher than that of the thin film solar cell to be compared. .

  Moreover, in the evaluation method of the series resistance of the transparent conductive film electrode according to the present invention, by using the evaluation method of the thin film solar cell, the resistance value of the series resistance component of the transparent conductive film electrode in the thin film solar cell to be evaluated is It can be judged whether it is larger or smaller than that of the transparent conductive film electrode in the thin film solar cell to be compared.

<1-5. Resistance value calculation process>
Furthermore, the method for evaluating a thin film solar cell according to the present invention may include a resistance value calculating step of calculating a series resistance value of the thin film solar cell based on the change amount calculated in the change amount calculating step. As a specific method of the resistance value calculating step, a conventionally known technique can be suitably used.

  Here, the “predetermined value” is, for example, the amount of change in the thin film solar cell of a plurality of standard samples calculated in advance (or afterwards) by the evaluation method according to the present invention, and each amount of change is the standard. What is respectively matched with the resistance value of the series resistance component of the thin film solar cell of a sample can be mentioned. In addition, what kind of thin film solar cell is used as the “standard sample” can be arbitrarily set, and is not particularly limited.

  The specific calculation process in the resistance value calculating step is not particularly limited, and examples thereof include the following method. That is, in advance (or after the fact), the amount of change in the thin film solar cell elements of a plurality of predetermined standard samples is calculated, and further the series resistance value of the thin film solar cell elements of the plurality of predetermined standard samples is obtained. The predetermined value is prepared. Then, the change amount calculated in the change amount calculation step is compared with a predetermined value, a predetermined value that matches the change amount is specified, and a resistance value corresponding to the specified predetermined value is determined as a thin film The method of calculating as a series resistance value of a solar cell can be mentioned.

  In addition, when there is no predetermined value that coincides with the actually calculated change amount in the change amount calculating step, the predetermined value closest to the change amount in the thin film solar cell to be evaluated is expressed as “change in thin film solar cell to be evaluated. It is also possible to calculate a predetermined value that matches the amount of change in the thin film solar cell to be evaluated by interpolating the amount of change and the resistance value of the plurality of standard samples in the thin film solar cell. May be.

  In the method for evaluating a thin film solar cell according to the present invention, the resistance value of the series resistance component of the thin film solar cell to be evaluated can be obtained by performing the resistance value calculating step. Therefore, by feeding back the result of the obtained resistance value to the manufacturing process of the thin film solar cell element, it is possible to achieve high efficiency and high reliability of the element performance of the thin film solar cell.

  Moreover, in the evaluation method of the series resistance of the transparent conductive film electrode which concerns on this invention, the resistance value of the series resistance component of the transparent conductive film electrode in the thin film solar cell of evaluation object is calculated | required by using the evaluation method of the said thin film solar cell. be able to.

<1-6. Current value identification process>
In the thin film solar cell evaluation method according to the present invention, in the current introduction step, a direct current in a forward direction with respect to the thin film solar cell element at a plurality of predetermined current values arbitrarily setting a direct current value. In the emission intensity measurement step, the emission intensity corresponding to the plurality of predetermined current values is measured, respectively, and in the change amount calculation step, the measured emission intensity is measured laterally of the thin-film solar cell element. Calculate the amount of change with respect to the distance in the direction, and determine whether or not the amount of change is substantially zero for the obtained multiple calculation results. The current corresponding to the amount of change determined to be substantially zero It is preferable to include a current value specifying step of specifying a value. As a specific method for the current value specifying step, a conventionally known technique can be preferably used.

  From the above reasoning, the present inventors have found that when the amount of change is substantially zero (when there is no difference in emission intensity between the current injection point and the other end), that is, the emission intensity is within the thin-film solar cell element. In the case of uniform in the case, it was considered that the introduced DC current was flowing through the thin film solar cell element without being attenuated. That is, when the amount of change is substantially zero, the introduced direct current is not affected by the series resistance component of the thin film solar cell element, in other words, the energy in the series resistance component of the transparent conductive film electrode of the thin film solar cell element. Thought to show that no loss occurred.

  Therefore, the present inventors further advanced the idea that the amount of change in emission intensity in the thin-film solar cell element and the energy loss in the series resistance component of the thin-film solar cell element are closely related to each other. By determining whether the amount of change in intensity is substantially zero, an operating current that causes no energy loss in the series resistance component of the thin film solar cell, particularly the series resistance component of the transparent conductive film electrode of the thin film solar cell, is obtained. We have also completed the required technology.

  That is, in the method for evaluating a thin film solar cell according to the present invention, the current introduction step, the emission intensity measurement step, the change amount calculation step, and the current value specification step are performed, and the thin film solar cell is set such that the specified current value becomes the operating current. By designing the structure of the battery, it is possible to manufacture a thin-film solar battery that does not generate energy loss in the series resistance component during power generation.

  Moreover, in the evaluation method of the series resistance of the transparent conductive film electrode according to the present invention, the structure of the thin film solar cell is designed so that the specified current value becomes the operating current by using the evaluation method of the thin film solar cell. Thus, it is possible to manufacture a thin film solar cell in which no energy loss occurs in the series resistance component of the transparent conductive film electrode of the thin film solar cell during power generation.

<1-7. Working current determination process>
Further, in the method for evaluating a thin film solar cell according to the present invention, the operation of determining the largest current value as the current value of the operating current of the thin film solar cell element from the current values specified by the current value specifying step. It is preferable to include an operation current determination step. As a specific method of the operating current determination step, a conventionally known technique can be suitably used.

  According to the method for evaluating a thin film solar cell according to the present invention described above, by including an operating current determination step, an optimum current value with no energy loss and high power generation efficiency is obtained in the series resistance component of the thin film solar cell element. Thin film solar cells can be designed for operating current. Therefore, it is possible to manufacture a thin film solar cell with high conversion efficiency in which no energy loss occurs in the series resistance component during power generation.

  Moreover, according to the evaluation method of the series resistance of the transparent conductive film electrode according to the present invention, the energy loss is the most in the series resistance component of the transparent conductive film electrode of the thin film solar cell element by using the evaluation method of the thin film solar cell. It is possible to design a thin-film solar cell having an operating current with an optimum current value with high power generation efficiency. Therefore, it is possible to manufacture a thin film solar cell with high conversion efficiency in which no energy loss occurs in the series resistance component of the transparent conductive film electrode during power generation.

<2. Thin-film solar cell evaluation system>
The evaluation apparatus for a thin film solar cell according to the present invention is an evaluation apparatus for a thin film solar cell that evaluates the performance of the thin film solar cell, and is a direct current in a forward direction with respect to the thin film solar cell element constituting the thin film solar cell. A current introduction part (current introduction means) for introducing light, a light emission intensity measurement part (light emission intensity measurement means) for measuring the light emission intensity of light generated from the thin-film solar cell element by the direct current introduced by the current introduction part, The light emission intensity measured by the light emission intensity measurement unit may be provided with a change amount calculation unit (change amount calculation means) for calculating a change amount with respect to the lateral distance of the thin film solar cell element. Specific conditions such as configuration, size, and shape are not particularly limited.

  Hereafter, each said member (each means) is demonstrated in detail. In addition, since the solar cell evaluation apparatus of the present invention executes the solar cell evaluation method of the present invention, the description of each member will be referred to the description of each step in the evaluation method described above, and overlapping. Omitted parts are omitted.

<2-1. Current introduction section>
The current introduction unit may be anything that can apply a so-called DC bias for injecting a DC current in the forward direction to the solar cell element, and its specific configuration is not particularly limited. Absent. That is, the current introduction unit may be any unit that performs the “current introduction step” described in the sections <1-1> and <1-6>. For example, a conventionally known constant current source or constant voltage source can be used.

<2-2. Luminescence intensity measurement section>
The light emission intensity measuring unit is not particularly limited as long as it can measure the light emission intensity when the solar cell element emits light by being forward-biased. Absent. In other words, the present emission intensity measuring unit only needs to execute the “emission intensity measuring step” described in the sections <1-2> and <1-6>. For example, a conventionally known photodetector such as a CCD camera or an image intensifier can be suitably used.

<2-3. Change amount calculation unit>
The change amount calculation unit only needs to be able to calculate the change amount with respect to the lateral distance of the thin-film solar cell element with respect to the emission intensity measured by the emission intensity measurement unit, and its specific configuration is particularly limited. Is not to be done. In other words, the change amount calculation unit only needs to execute the “change amount calculation step” described in the sections <1-3> and <1-6>. For example, a conventionally known arithmetic device such as a PC can be suitably used.

  Therefore, the thin-film solar cell evaluation apparatus according to the present invention can be rephrased as one for executing the “thin-film solar cell evaluation method” described in the section <1>.

  The thin-film solar cell evaluation apparatus according to the present invention may include a scanning unit (scanning means) of a mechanism capable of two-dimensional scanning in addition to a one-dimensional scanning mechanism such as a line scanner. By providing such a scanning unit, a large-sized thin-film solar cell including a large number of thin-film solar cell elements can be evaluated while scanning the entire module. Note that the scanning unit may be provided in the evaluation apparatus, and conversely, may be provided in the thin film solar cell element to be evaluated. In addition, it is also possible to evaluate the whole thin film solar cell module at once from the upper part of a thin film solar cell element, without performing scanning by a scanning part, and it is also possible to evaluate only a part of thin film solar cell module.

<2-4. Resistance value determination unit>
Further, in the thin-film solar cell evaluation device according to the present invention, when the change amount calculated by the change amount calculation unit is larger than a predetermined value, it is determined that the series resistance value is large, and is smaller than the predetermined value. In this case, it is preferable to include a resistance value determination unit (resistance value determination means) that determines that the series resistance value is small.

  The specific configuration of the resistance value determination unit is not particularly limited. That is, the resistance value determining unit may be any unit that executes the “resistance value determining step” described in the section <1-4>. For example, a conventionally known arithmetic device such as a PC can be suitably used. Therefore, the above <1-4> column can be referred to for the specific content performed by the resistance value determination unit.

<2-5. Resistance value calculation section>
Further, in the thin-film solar cell evaluation apparatus according to the present invention, a resistance value calculation unit (resistance value calculation unit) that calculates the series resistance value of the thin-film solar cell based on the change amount calculated by the change amount calculation unit. ) May be provided.

  The specific configuration of the resistance value calculation unit is not particularly limited. That is, the resistance value calculation unit may be any unit that performs the “resistance value calculation step” described in the section <1-5>. For example, a conventionally known arithmetic device such as a PC can be suitably used. Therefore, the above <1-5> column can be referred to for the specific content performed by the resistance value calculation unit.

<2-6. Current value identification section>
Further, in the thin-film solar cell evaluation apparatus according to the present invention, the current introduction unit is forwardly directed to the thin-film solar cell element at a plurality of predetermined current values in which the current value of the direct current is arbitrarily set. DC current is introduced, and the emission intensity measurement unit measures emission intensity corresponding to the plurality of predetermined current values, and the change amount calculation unit is measured by the emission intensity measurement unit. For each of the emission intensities, the amount of change with respect to the lateral distance of the thin-film solar cell element is calculated, and for each of the obtained calculation results, whether or not the amount of change is substantially zero. It is preferable to include a current value specifying unit (current value specifying means) that determines and specifies a current value corresponding to the amount of change determined to be substantially zero.

  The specific configuration of the current value specifying unit is not particularly limited. That is, the current value specifying unit may be any unit that executes the “current value specifying step” described in the section <1-6>. For example, a conventionally known arithmetic device such as a PC can be suitably used. Therefore, the above <1-6> column can be referred to for the specific contents performed by the current value identification unit.

<2-7. Operating current determination section>
Moreover, in the thin-film solar cell evaluation apparatus according to the present invention, the operation of determining the largest current value as the current value of the operating current of the thin-film solar cell element from the current values specified by the current value specifying unit. It is preferable to provide a current determination unit (operation current determination means).

  The specific configuration of the operating current determination unit is not particularly limited. That is, the operating current determination unit may be any unit that performs the “operating current determination step” described in the section <1-7>. For example, a conventionally known arithmetic device such as a PC can be suitably used. Therefore, the above <1-7> column can be referred to for the specific contents performed by the operating current determination unit.

  In addition, regarding the thin film solar cell evaluation apparatus, it is needless to say that the description regarding the thin film solar cell evaluation method described in the section <1> can be appropriately referred to and used for matters other than those described above. .

<2-7. Overview of evaluation device>
Next, the outline | summary of the evaluation apparatus 10 which evaluates the serial resistance of the thin film solar cell 7 is demonstrated using FIG. FIG. 3 is a diagram showing an embodiment of an evaluation apparatus 10 for a thin-film solar cell according to the present invention. As shown in the figure, the evaluation apparatus 10 for the thin-film solar cell 7 according to this embodiment includes a dark box 1, a light emission intensity measurement unit 12, comb-shaped probes 4 and 5, a DC power supply 6, electrodes 8 and 9, and a calculation unit 20. It has. Moreover, the thin film solar cell 7 is an evaluation object. The thin film solar cell 7 has a configuration in which a plurality of thin film solar cell elements are connected. The thin film solar cell 7 may be a module in which a plurality of thin film solar cell elements are connected.

  The dark box 1 is for forming a dark state for facilitating measurement of the light emission intensity of the thin-film solar cell 7. The dark box 1 is formed with a window hole. This window hole is used when evaluating the thin film solar cell module or panel provided in the vertical direction.

  The light emission intensity measuring unit 12 functions as light emission intensity measuring means including a CCD camera, and includes a cooled CCD (−50 ° C.) 2 and a lens 3. The emission intensity measurement unit 12 is formed to be rotatable by 90 °. Thereby, the solar cell module provided in the vertical direction can be evaluated. Note that a normal lens or a zoom lens can be used as the lens.

  Moreover, when evaluating the cell (thin film solar cell element) which comprises the thin film solar cell 7 from which size differs using a CCD camera as the light emission intensity measurement part 12, it describes in following Table 1 (C9299-02 by Hamamatsu Photonics). A CCD camera having the performance as described above can be used.

  Specifically, in the normal shooting mode, as shown in FIG. 3, the CCD camera is installed on the upper part of the thin film solar cell 7 for shooting. In the module shooting mode, the solar cell module is placed outside the dark box 1. Install and rotate the CCD camera 90 ° to take and measure.

  In addition, the size (cell size) of the thin film solar cell 7 to be evaluated in the normal photographing mode is, for example, a size: about 10 mm × 10 mm, 20 mm × 20 mm, 100 mm × 100 mm, 150 mm × 150 mm, 160 mm × 160 mm, The thing of 200 mm x 200 mm and thickness: 0.3 mm or less can be used.

  Further, in the present embodiment, the distance between the lens 3 of the light emission intensity measurement unit 12 and the thin film solar cell 7 is set to 150 mm or more and within 400 mm, and the light emission intensity measurement unit 12 is between the thin film solar cell 7. It is preferable to be installed so as to be movable up and down.

  The comb probes 4 and 5 are surface contacts for applying a current to the thin film solar cell 7. As shown in the figure, the comb probes 4 and 5 are comb-shaped probes, and are connected to electrodes 8 and 9 connected to both ends of the thin film solar cell 7, respectively. Comb probe 4 is connected to electrode 8 and comb probe 5 is connected to electrode 9. It is preferable that the probe has a comb structure because a current can be uniformly applied to the thin film solar cell 7. In addition, although the space | interval of "comb" in a comb-shaped probe is not specifically limited, For example, what is necessary is just 9 mm. Moreover, the thickness of one comb of the probe can be 1 mm.

As the DC power source 6, a normal DC power supply (which can be injected at a current density of 1 to 50 mA / cm ² per thin film solar cell element per thin film solar cell element) can be used. In addition, when evaluating a thin film solar cell element, about 1-2V is preferable per thin film solar cell. For example, when evaluating a thin film solar cell module in which 180 thin film solar cell elements are connected, it is preferably about 180 to 360V.

  The electrodes 8 and 9 are electrodes for applying a current to the thin film solar cell 7 and are formed of a metal such as aluminum or silver.

  The comb probes 4 and 5, the DC power supply 6, and the electrodes 8 and 9 function as a current introduction unit 11. The electrode 8 is fixedly connected to the negative-side comb probe 4 of the DC power source 6, and the electrode 9 is fixedly connected to the positive-side comb probe 5 of the DC power source 6. In the present embodiment, the comb probes 4 and 5, the DC power source 6 and the electrodes 8 and 9 are used as the current introduction unit 11, but the present invention is not limited to this.

The computing unit 20 functions as computing means for evaluating the performance of the thin-film solar cell 7. In the present embodiment, an image processor is used. The software to be used is not particularly limited as long as the object of the present invention can be achieved. For example, it is preferable to use software having the following configuration.
An image that can store ⁸ bits (2 ⁸ = 256 gradations) or 16 bits (2 ¹⁶ = 65536 gradations).
・ After detecting (photographing) the light emission characteristics of the thin-film solar electronic device, select the area on the screen to obtain and save the brightness profile data.
・ Spectrostable.
・ Those that can acquire high-sensitivity images (image intensifier cameras), for example, those that can measure emissions when reverse current is applied.

Further, the following configuration is more preferable.
・ Improved that when the data is read with spreadsheet software and converted into an image, the photographed image is rotated 90 degrees.
・ Simple switching of binning mode is possible.
・ Automatic creation program for histogram of light emission intensity.
・ Automatic measurement of length and width of low intensity (dark areas). Automatic detection of one centimeter or more.
・ Calculate the average value of the light emission intensity in the selected range. It is preferable that an average value obtained by subtracting the value of the grid portion can also be measured.

  In the dark box 1, a light emission intensity measuring unit 12, comb probes 4 and 5, electrodes 8 and 9, and a thin film solar cell 7 are installed. The emission intensity measurement unit 12 is installed at a position where the emission characteristics of the thin film solar cell 7 can be detected. In the case of the present embodiment, the emission intensity measurement unit 12 is provided on the upper part of the thin film solar cell 7.

<2-8. Functions of evaluation device>
Next, the function of the evaluation apparatus 10 will be described based on FIG. FIG. 1 is a functional block diagram showing a main configuration of the evaluation apparatus 10. As illustrated in FIG. 1, the evaluation device 10 includes a current introduction unit 11, a light emission intensity measurement unit 12, and a calculation unit 20.

  The calculation unit 20 calculates the light emission intensity measured by the light emission intensity measurement unit 12 in order to evaluate the performance of the thin film solar cell 7, and includes a change amount calculation unit 21, a resistance value determination unit 22, and a resistance value calculation unit. 23, a current value specifying unit 24 and an operating current determining unit 25 are included. The arithmetic unit 20 uses an image processor in the present embodiment, but is not limited to this, and a conventionally known arithmetic device or the like can be suitably used.

  Specific functions of the current introduction unit 11, the emission intensity measurement unit 12, the change amount calculation unit 21, the resistance value determination unit 22, the resistance value calculation unit 23, the current value specification unit 24, and the operating current determination unit 25 are described in <2- Since it is as having demonstrated by 1>-<2-7>, it abbreviate | omits here.

  Note that the evaluation device 10 may include a storage unit (not shown). Data relating to the predetermined value may be stored in the storage unit. In this case, the resistance value determination unit 22 or the resistance value calculation unit 23 reads a predetermined value from the storage unit, and performs the process of the resistance value determination step or the resistance value calculation step. Further, the present invention is not limited to this, and data relating to a predetermined value may be stored in an external storage device, and the resistance value determination unit 22 or the resistance value calculation unit 23 may read out from the external storage device.

<2-9. Change calculation processing and resistance value determination / calculation processing>
Next, specific processing relating to calculation of the change amount and determination / calculation of the resistance value performed by the evaluation apparatus 10 will be described with reference to FIG. FIG. 4 is a flowchart showing the processing of the evaluation apparatus 10 regarding the calculation of the change amount and the determination / calculation of the resistance value.

  First, the current introduction unit 11 introduces a current in the forward direction with respect to the thin-film solar cell 7 (S1). The thin film solar cell 7 emits light by the introduced current, and the light emission intensity measuring unit 12 detects the light emitted from the thin film solar cell 7 and measures the intensity (light emission intensity) of the detected light (S2).

  Next, the change amount calculation unit 21 calculates the change amount with respect to the distance in the horizontal direction with respect to the light emission intensity measured by the light emission intensity measurement unit 12 (S3). The resistance value determination unit 22 determines that the series resistance value is large when the change amount calculated by the change amount calculation unit 21 is larger than the predetermined value, and determines that the series resistance value is smaller than the predetermined value. It determines with it being small (S4).

  In S <b> 4, the resistance value calculation unit 23 may calculate the series resistance value of the thin-film solar cell based on the change amount calculated by the change amount calculation unit 21.

<2-10. Current value identification process and operating current determination process>
Next, specific processing relating to the specification of the current value and the determination of the operating current performed by the evaluation device 10 will be described with reference to FIG. FIG. 5 is a flowchart showing processing of the evaluation apparatus 10 relating to specification of the current value and determination of the operating current.

  First, the current introduction unit 11 selects one current value from a plurality of arbitrarily set current values. The current introduction unit 11 introduces the current having the selected current value in the forward direction with respect to the thin-film solar cell 7 (S11). Since the thin film solar cell 7 emits light by the introduced current, the light emission intensity measuring unit 12 detects the light emitted from the thin film solar cell 7 and measures the intensity (light emission intensity) of the detected light (S12).

  Next, the change amount calculation unit 21 calculates the change amount with respect to the distance in the horizontal direction for the light emission intensity measured by the light emission intensity measurement unit 12 (S13).

  Then, the change amount calculation unit 21 checks whether or not the change amount has been calculated for all of a plurality of arbitrarily set predetermined current values (S14). When the change amount calculation unit 21 does not calculate the change amount for all of the plurality of predetermined current values arbitrarily set (NO in S14), the current introduction unit 11 sets the plurality of predetermined current values arbitrarily set. One current value that has not yet been introduced is selected from the list (S15). And the process of S11-S13 is performed.

  On the other hand, when the change amount calculation unit 21 calculates the change amount for all of a plurality of predetermined current values arbitrarily set (YES in S14), the current value specifying unit 24 calculates the change amount calculated by the change amount calculation unit 21. Is determined to be substantially zero, and a current value corresponding to the amount of change determined to be substantially zero is specified (S16).

  Then, the operating current determining unit 25 determines the largest value among the current values specified by the current value specifying unit 24 as the value of the operating current of the thin film solar cell 7 to be evaluated (S17).

  As described above, according to the thin film solar cell evaluation apparatus 10, the thin film solar cell evaluation method can be easily and reliably performed. In this case, there is no need for a large and complicated device as in the conventional evaluation device, and the performance of the thin film solar cell device can be evaluated by accurately measuring the emission intensity of the thin film solar cell device with simple equipment. .

In the above description, the evaluation apparatus and the evaluation method for thin film solar cell elements and thin film solar cell modules have been mainly described. However, the present invention is not limited to this, and a thin film in which a plurality of thin film solar cell modules are connected. Evaluation of solar cell panels can also be performed. In this case, the intensity and voltage of the applied current, the shape of the probe, and the like can be appropriately changed as necessary. For example, the current in the forward direction may be set to be a total current corresponding to 1 to 80 _{[mA / cm} ² ] per thin film solar cell element. Moreover, you may change from a dark box to a dark room according to the magnitude | size of a thin film solar cell module. Furthermore, as described above, the thin-film solar cell module may be installed in the vertical direction, and the emission intensity measurement unit 12 in FIG.

  Finally, each block of the evaluation apparatus 10 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the evaluation apparatus 10 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of the evaluation apparatus 10 that is software that realizes the above-described functions is recorded so as to be readable by a computer. This can also be achieved by supplying the evaluation device 10 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the evaluation apparatus 10 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  In addition, by using the evaluation apparatus of the series resistance of a transparent conductive film electrode provided with the evaluation apparatus of the said thin film solar cell, and also provided with the evaluation means which evaluates the series resistance in a transparent conductive film electrode based on the result of the said evaluation apparatus Based on the evaluated serial component of the thin film solar cell, the series resistance of the transparent conductive film electrode in the thin film solar cell element can be evaluated.

<3. Manufacturing method of thin film solar cell>
As described above, the thin-film solar cell evaluation method and evaluation apparatus according to the present invention can easily and accurately evaluate series resistance components at the product level, which could not be performed conventionally.

  Further, the thin film solar cell evaluation method or evaluation apparatus according to the present invention does not require, for example, a scanning probe (electron beam, laser), and can perform simple measurement, as compared with the conventional technology, and can be used for large-scale equipment. Therefore, it is possible to observe and evaluate the product in a product state (completed or installed in a manufacturing factory).

  Moreover, the resistance value of the series resistance component of the thin film solar cell can be determined / calculated by using the evaluation method and the evaluation apparatus for the thin film solar cell according to the present invention, and in addition, the series resistance component of the thin film solar cell. Therefore, the optimum operating current with high conversion efficiency can be determined.

  Therefore, by incorporating the thin film solar cell evaluation method according to the present invention as one step of the thin film solar cell manufacturing method, the thin film solar cell having a series resistance component with a reduced resistance value while improving or maintaining the light transmittance. A battery can be manufactured. In addition, energy loss in the series resistance component of the thin-film solar cell does not occur during power generation, and a thin-film solar cell that operates at an optimal operating current with high conversion efficiency can be manufactured.

  Hereinafter, examples will be shown, and the embodiment of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail. Further, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the present invention is also applied to the embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention.

<Example 1>
First, a current was introduced into the thin film solar cell in the forward direction, and the state of the emitted thin film solar cell module was observed with a CCD camera. Specifically, a voltage of 8.6 V is applied to a thin film solar cell module (sample number: J24) composed of eight thin film solar cell elements so that a direct current of 200 mA flows in the forward direction. The thin-film solar cell module was observed for light emission using a Si CCD camera. The result is shown in FIG. The current was injected from the right side to the left side of each thin film solar cell element shown in FIG.

  As shown in the figure, the right side (the side where the current is injected) of each thin film solar cell element is bright, and it can be seen that the emission intensity decreases as it proceeds in the lateral direction. Note that a portion that looks whitish is a region that emits strong light, and a portion that appears black is a region that emits weak light.

  At this time, the light emission intensity of the thin film solar cell module in the lateral direction was measured. The result is shown in FIG. The horizontal axis in FIG. 6 (b) indicates the distance in which the direction from the left side to the right side in FIG. 6 (a) (the direction opposite to the horizontal direction) is positive, and the vertical axis indicates the emission intensity. It can be seen from FIG. 6B that there are 8 peaks. Considering the relationship between the emission intensity and the position of each thin film solar cell element, the eight peaks correspond to the eight thin film solar cell elements. “Top” shown in the graph of FIG. 6B indicates the maximum value of the emission intensity in each thin film solar cell element, and “Bottom” indicates the minimum value of the emission intensity in each thin film solar cell element. The maximum value (“Top”) of the emission intensity is the emission intensity at the right end of each thin-film solar cell element shown in FIG. 6A, and the minimum emission intensity (“Bottom”) is the value of each thin-film solar cell element. The leftmost emission intensity. That is, in each thin film solar cell element, the emission intensity is the highest at the current injection point (right end), and the emission intensity decreases from the injection point to the other end (left end).

  Next, the voltage applied so that the electric current which flows into a thin film solar cell module might be set to 50 mA was changed, and the same measurement as the above was performed. The result is shown in FIG. Similarly to FIG. 6B, the horizontal axis of FIG. 6C indicates the distance with the positive direction from the left side to the right side of FIG. 6A, and the vertical axis indicates the emission intensity. When FIG.6 (c) is seen, similarly to FIG.6 (b), in each thin film solar cell element, the emitted light intensity by the side which injected the electric current is large, and the emitted light intensity is attenuate | damped according to the distance of a horizontal direction. Recognize. However, compared to FIG. 6B, the measured emission intensity is generally small, and although it is affected by noise, the amount of change in the lateral direction can be determined.

  Next, various current values were introduced into the same thin-film solar cell module, and the emission intensity of “Top” and “Bottom” at each current value was measured. The result is shown in FIG. From the results shown in FIG. 7, the Top portion increases according to the amount of injected current, but the Bottom portion is affected by the series resistance and becomes saturated due to a certain current ground abnormality.

  Moreover, the emission spectrum of the thin film solar cell module was measured. The result is shown in FIG. The horizontal axis in FIG. 8 indicates the wavelength, and the vertical axis indicates the emission intensity. From the results shown in FIG. 8, it was found that the light emitted from the thin film solar cell module had a peak in the vicinity of a wavelength of 1000 nm to 1400 nm.

<Example 2>
In the second embodiment, the emission intensity of the thin-film solar cell element is measured using an InGaAs CCD camera useful for detecting light having a peak in the vicinity of a wavelength of 1000 nm to 1400 nm, and the current at which the amount of change becomes substantially zero. I decided to look for the value. Specifically, currents of various current values are introduced into the thin film solar cell module (sample number: J24), and the state of the emitted thin film solar cell module is observed with the CCD camera using an InGaAs CCD camera. did. First, currents of 20 mA, 30 mA, and 80 mA were introduced into the thin film solar cell module. The results are shown in FIGS. Moreover, the light emission intensity of the thin film solar cell module in the horizontal direction at each current value was measured. The results are shown in FIGS. 9 (d) to 9 (f).

  Also in the second example, the current was injected from the right side to the left side of each thin film solar cell element shown in FIGS.

  9 (d) to 9 (f), as in FIGS. 6 (b) and 6 (c), the horizontal axis represents the distance in which the direction from the left side to the right side in FIGS. 9 (a) to 9 (c) is positive. The vertical axis indicates the emission intensity.

  9D to 9F, it can be seen that the smaller the current value to be introduced, the smaller the amount of change in the emission intensity with respect to the lateral distance in each thin film solar cell element. The amount of change of the emission intensity with respect to the lateral distance is represented by “slope”. The broken lines drawn in FIGS. 9D to 9F indicate the “slope”, and it can be seen that the slope becomes gentler as the current value to be introduced is smaller.

  As shown in FIG. 9D, the amount of change (slope) is almost zero. From this, it is understood that when a current of 20 mA is introduced into the thin film solar cell module, the energy loss in the series resistance component of the thin film solar cell element is least generated.

  The thin film solar cell evaluation method and the like according to the present invention can be used for quality inspection and the like performed when manufacturing a thin film solar cell module.

7 thin film solar cell 7a thin film solar cell element 10 evaluation apparatus 11 current introduction part (current introduction means)
12 Luminescence intensity measuring part (luminescence intensity measuring means)
20 arithmetic unit 21 change amount calculation unit (change amount calculation means)
22 Resistance value determination unit (resistance value determination means)
23. Resistance value calculation unit (resistance value calculation means)
24 Current value specifying unit (current value specifying means)
25 Operating current determining section (Operating current determining means)
32 Upper transparent conductive film electrode (transparent conductive film electrode)

Claims (13)

An evaluation method of a thin film solar cell for evaluating the performance of the thin film solar cell,
For the thin film solar cell element constituting the thin film solar cell, a current introduction step for introducing a direct current in the forward direction;
A light emission intensity measuring step of measuring light emission intensity of light generated from the thin film solar cell element by the current introduction step;
An evaluation method comprising: a change amount calculation step of calculating a change amount with respect to a distance in a lateral direction of the thin film solar cell element with respect to the light emission intensity measured by the light emission intensity measurement step.   Further, when the change amount calculated in the change amount calculation step is larger than a predetermined value, it is determined that the series resistance value is large, and when the change amount is smaller than the predetermined value, the resistance value determination is determined that the series resistance value is small. The evaluation method according to claim 1, further comprising a step.   The evaluation method according to claim 1, further comprising a resistance value calculation step of calculating a series resistance value of the thin-film solar cell based on the change amount calculated in the change amount calculation step. In the current introduction step, a direct current is introduced in the forward direction with respect to the thin-film solar cell element at a plurality of predetermined current values arbitrarily setting the current value of the direct current,
In the emission intensity measurement step, the emission intensity corresponding to the plurality of predetermined current values is measured,
In the change amount calculation step, for each measured light emission intensity, the change amount with respect to the lateral distance of the thin film solar cell element is calculated,
Furthermore, it includes a current value specifying step of determining whether or not the change amount is substantially zero for a plurality of obtained calculation results and specifying a current value corresponding to the change amount determined to be substantially zero. The evaluation method according to claim 1, wherein:   The method further comprises an operating current determining step of determining the largest current value among the current values specified by the current value specifying step as a current value of the operating current of the thin-film solar cell element. 4. The evaluation method according to 4.   The evaluation method of the serial resistance in the transparent conductive film electrode which evaluates the serial resistance of the transparent conductive film electrode in a thin film solar cell element using the evaluation method of any one of Claims 1-5. A thin-film solar cell evaluation apparatus for evaluating the performance of a thin-film solar cell,
Current introduction means for introducing a direct current in the forward direction with respect to the thin film solar cell element constituting the thin film solar cell,
Luminous intensity measuring means for measuring the luminous intensity of light generated from the thin film solar cell element by the direct current introduced by the current introducing means;
An evaluation apparatus comprising: a change amount calculating means for calculating a change amount with respect to a lateral distance of the thin film solar cell element with respect to the light emission intensity measured by the light emission intensity measuring means.   Further, when the change amount calculated by the change amount calculating means is larger than a predetermined value, it is determined that the series resistance value is large, and when it is smaller than the predetermined value, the resistance value determination is determined that the series resistance value is small. The evaluation apparatus according to claim 7, further comprising means.   8. The evaluation apparatus according to claim 7, further comprising resistance value calculation means for calculating a series resistance value of the thin film solar cell based on the change amount calculated by the change amount calculation means. The current introduction means is for introducing a direct current in the forward direction with respect to the thin-film solar cell element at a plurality of predetermined current values arbitrarily setting the current value of the direct current,
The emission intensity measuring means measures emission intensity corresponding to the plurality of predetermined current values,
The change amount calculation means calculates the change amount with respect to the lateral distance of the thin-film solar cell element for each emission intensity measured by the emission intensity measurement means,
Furthermore, it is provided with a current value specifying means for determining whether or not the change amount is substantially zero for a plurality of obtained calculation results, and specifying a current value corresponding to the change amount determined to be substantially zero. The evaluation apparatus according to claim 7.   The operation current determining means for determining the largest current value as the current value of the operation current of the thin-film solar cell element from the current values specified by the current value specifying means. The evaluation device described.   A transparent conductive film electrode comprising the evaluation device according to any one of claims 7 to 11, and further comprising evaluation means for evaluating a series resistance in the transparent conductive film electrode based on a result of the evaluation device. Evaluation device for series resistance in   The manufacturing method of the thin film solar cell characterized by including the evaluation method of the thin film solar cell of any one of Claims 1-5 as 1 process.