TWI427809B - Manufacturing method for silicon based thin film solar cell module - Google Patents

Description

矽 Thin film solar cell module manufacturing method

The invention relates to a method for manufacturing a solar cell, in particular to a method for manufacturing a tantalum thin film solar cell module.

The thin film solar cell of the prior art is formed by a series of steps of forming a front electrode on a glass substrate, forming a photoelectric conversion layer on the front electrode, and forming a rear electrode on the photoelectric conversion layer. In this case, since the front electrode corresponds to the light incident surface, the front electrode is made of a transparent conductive material such as a zinc oxide (ZnO) film. When a larger sized substrate is used, power loss is increased due to the resistance of the transparent conductive layer. Therefore, a method for reducing power loss is to divide a thin film type solar cell into a plurality of unit cells which are connected in series to each other to reduce power loss due to resistance of the transparent conductive material. This series of steps is formed using laser cutting. The laser cutting step is performed by cutting the front electrode on the substrate with a first laser, cutting the photoelectric conversion layer on the front electrode with a second laser, and cutting the rear electrode on the photoelectric conversion layer with a third laser. However, the laser incision caused by the three laser cutting processes and the area between the three laser incisions form an ineffective area where photoelectric conversion is impossible, that is, the width of the ineffective area is three laser incisions. The sum of the width and the distance between the three laser cuts, which reduces the current generation, thereby reducing the power output of the module. On the other hand, the surrounding hot zone during laser cutting may cause the material to crystallize. Although reducing the distance between the three laser cuts can reduce the ineffective area, it may cause leakage current due to crystallization of the hot zone. Therefore, defining the preferred width of the ineffective area and the laser cutting process with it has become an urgently important technology in the development of thin film solar cell processes.

U.S. Patent No. 6,384,315, entitled: Solar Cell Module, which primarily discloses a packaging method for a tantalum thin film solar cell module. Although the case reveals laser cutting conditions, there is no disclosure and definition of the effective area width to improve productivity. See also U.S. Patent No. 6,455,347, entitled: Method of fabricating thin-film photovoltaic module. The case mainly reveals the laser cutting mode of the thin film solar cell module, which includes the laser wavelength, the laser mode, and the laser travel path. However, there is no disclosure in the case of the optimization of the width of the invalid area. Therefore, it is necessary to propose a laser cutting method corresponding to the case and to define the optimized invalid region width to achieve the purpose of optimizing the laser process.

In view of the above, there is a need to propose a laser cutting method for a thin film solar cell that can achieve an optimized ineffective region width to achieve a high-performance tantalum solar cell mass production target.

For the sake of the job, the present invention provides a method for manufacturing a tantalum thin film solar cell module. By defining a preferred width of the ineffective region, the waste of the area can be avoided to optimize the laser cutting process, and the performance of the thin film solar cell can be improved. And the value of capacity. In addition, the present invention is incorporated by reference to U.S. Patent No. 6,384,315, entitled "Solar Cell Module" and U.S. Patent No. 6,455,347, entitled "Method of Fabricating Thin- Film photovoltaic module)" is cited as a reference.

The invention provides a method for manufacturing a tantalum thin film solar cell module. By defining a preferred width condition of the ineffective region, waste of power generation area can be avoided, thereby improving the efficiency of the tantalum thin film solar cell, and achieving a thin film solar cell module. Process optimization.

The present invention mainly comprises the steps of: depositing a transparent conductive film on a substrate; performing a first laser process, forming a plurality of conductive film units with a transparent conductive film by a first laser cut; depositing a photoelectric conversion layer on the conductive film unit; a second laser process, at a first distance from the first laser cut, forming a plurality of conversion layer units by the second laser cut with the second laser cut; depositing an electrode layer on the conversion layer unit; performing a third laser a plurality of electrode units are formed by the third laser incision at a second distance from the second laser incision, and the unit electrical level is electrically connected to the conductive film unit through the second laser incision; a fourth laser process for removing a portion of the conversion layer unit and the electrode unit outside the substrate to form an interval, and the interval distinguishes the power generation region, wherein the power generation region has a plurality of tandem solar cells, and wherein the first The sum of the laser slit width, the second laser slit width, the third laser slit width, the first distance, and the second distance is less than 5 of the width of the power generating region %.

While the invention may be embodied in various forms, the embodiments illustrated in the drawings It is not intended to limit the invention to the particular embodiments illustrated and/or described.

Please refer to FIG. 1 , which is a flow chart of a method for manufacturing a tantalum thin film solar cell module according to the present invention, which is further illustrated by the following figures 2A to 2G:

Step 310: depositing a transparent conductive film.

Please refer to FIG. 2A , which is a schematic diagram of a process of the thin film solar cell module of the present invention. The first step is to deposit a transparent conductive film 120 on the substrate 110 , wherein the substrate 110 is selected from the group consisting of glass, plastic substrate and transparent. One of a flexible substrate, a semiconductive substrate, and an insulating substrate. In this embodiment, a glass substrate is used. The transparent conductive film 120 is used for extracting electric energy and improving the efficiency of photoelectric conversion. The material thereof may be selected from indium tin oxide, tin dioxide, zinc oxide, impurity-containing tin dioxide, impurity-containing zinc oxide, nickel, gold, silver, Titanium, copper, palladium, and aluminum. The process of the transparent conductive film 120 is selected from any one of the group consisting of a vapor deposition method, a sputtering method, a plating method, a chemical vapor deposition method, and a printing method. However, in order to obtain a preferred surface roughness, the transparent conductive film 120 is deposited by low pressure chemical vapor deposition or by a sputtering process followed by a post etching process. In a preferred embodiment, the material of the transparent conductive film is selected from impurity-containing tin dioxide having a transmittance of 85% or more and a sheet resistance value of between 5 Ω/□ and 10 Ω/□. In this embodiment, the thickness is between 100 nm and 800 nm.

Step 320: Form a plurality of conductive film units.

Please refer to FIG. 2B , which is a schematic diagram of the process of the thin film solar cell module of the present invention (2). In this step, the conductive film unit 120a is formed on the substrate 110 by the first laser cut 130 by performing the first laser process. , 120b, 120c and 120d. The width L1 of the first laser cut 130 is preferably between 30 um and 110 um, and the laser wavelength of the first laser process is selected from one of a fundamental frequency and a second frequency of the YAG laser. The wavelengths are 1064 nm and 532 nm, respectively, to correspond to the wavelength of light that the transparent conductive film can absorb. When the first transparent conductive film layer (such as zinc oxide) is stripped, the relationship between the wavelength and the absorption coefficient is as shown in Fig. 3, which shows that the absorption rate of zinc oxide by infrared light is better than that of green light. In addition, for the unannealed SnO ₂ film, the radiant energy of the laser beam will cause the SnO _{2 to be} converted into the insulating material SnO. However, as the laser energy density increases, the amount of laser energy penetrating through the transparent conductive film to the glass substrate will also increase, which will cause the impurities in the substrate to volatilize and deposit on the surface of the insulating material SnO. This is the main reason for the decrease in the resistance of the transparent conductive film. On the contrary, with the step of the annealing treatment, the insulating material SnO and the impurities are substantially changed, thereby causing a slope change in which the resistance curve is inversely proportional to the unannealed SnO ₂ resistance. It should be noted that the resistance of the transparent conductive film after cutting needs to be greater than 1 MΩ. Therefore, in order to achieve a transparent conductive film cell having a good degree of isolation, the X/D and the laser energy density used can reach the desired degree of resistance as long as 0.56 and 21 J/cm ² , respectively.

Step 330: depositing a photoelectric conversion layer.

Please refer to FIG. 2C, which is a schematic diagram (3) of the process of the tantalum thin film solar cell module of the present invention. This step deposits the photoelectric conversion layer 140 on the conductive film units 120a, 120b, 120c, and 120d. The photoelectric conversion layer 140 is composed of a germanium-based material, and the photoelectric conversion layer 140 is defined to include at least one P-type semiconductor layer, at least one intrinsic type (i-type) semiconductor layer, and at least one N-type semiconductor layer. Among them, the definition of the P-type semiconductor layer: the inclusion of impurities (Impurities) in the original intrinsic material to generate excess holes, and the holes constitute the semiconductor layer of the majority carrier. Example: In the case of germanium or germanium semiconductors, in their intrinsic semiconductors, impurities doped with trivalent atoms form extra holes, making holes act as currents.

The N-type semiconductor layer refers to a semiconductor in which an impurity added to an intrinsic material generates excess electrons and electrons constitute a majority carrier, which is called an N-type semiconductor layer. For example, in the case of germanium or germanium semiconductors, if an intrinsic semiconductor is doped with impurities of a five-valent atom, excess electrons are formed, and electron current is the main mode of operation. The intrinsic (i-type) semiconductor layer has the greatest influence on the electrical characteristics of the thin film type solar cell. When the electron and the hole are conducted inside the material, if the thickness of the intrinsic type (i type) semiconductor layer is too thick, the coincidence probability is extremely high. High, in order to avoid this phenomenon, the intrinsic (i-type) semiconductor layer should not be too thick. On the other hand, when the thickness of the intrinsic type (i type) semiconductor layer is too thin, the light absorption is insufficient.

The doping method of the P-type semiconductor layer and the N-type semiconductor layer is selected in the present invention by gas doping, thermal diffusion, solid phase crystallization (SPC) or excimer laser. Processes such as annealing (Excimer laser anneal, ELA) are the main process methods. It should be noted that the preparation sources of different P-type semiconductor layers, intrinsic (i-type) semiconductor layers, and N-type semiconductor layers may also affect the quality of the photoelectric characteristics thereof; and the P-type semiconductor layer, the intrinsic type (i Type) semiconductor layer, N-type semiconductor layer is prepared by mixing decane gas with hydrogen; decane gas, hydrogen mixed with argon; decane gas, decane gas mixed with hydrogen; decane gas, decane gas, hydrogen gas and argon gas Mix any of the processes in the group.

Step 340: Form a plurality of conversion layer units.

Please refer to FIG. 2D, which is a schematic diagram (4) of the process of the tantalum thin film solar cell module of the present invention. This step is performed at a first distance 150 from the first laser incision 130 by performing a second laser process. The second laser cut 160 forms the conversion layer unit 140a, 140b, 140c, 140d. The width W1 of the first distance 150 is preferably between 50 um and 110 um in the embodiment of the invention, and the width L2 of the second laser cut 160 is preferably between 30 um and 110 um. And because the light absorption wavelength of the ruthenium-based material is low, the laser wavelength of the second laser process is selected from one of the second frequency and the third frequency of the higher energy of the YAG laser, and the wavelengths thereof are respectively It is 532 nm and 266 nm. It should be noted that the parameters used vary depending on the width of the laser cutting. When the laser cutting width is 50 um to 100 um, the detailed parameters of the Q-Switched YAG laser-cut back electrode and the photoelectric conversion layer are as follows: oscillation frequency is 3 KHz, average output power is 500 mW, laser pulse With a width of 10 nsec, the relative movement speed of the glass substrate to the laser cutting is 3.5 um/min. When the laser cutting width is greater than 100 um, the Q-Switched YAG laser parameters used to cut the back electrode and the photoelectric conversion layer are as follows: the oscillation frequency is 10 KHz, the average output power is 1.5 W, and the laser pulse width is For 50 nsec, the relative movement speed of the glass substrate to the laser cutting is 200 mm/sec.

Step 350: depositing an electrode layer.

Please refer to FIG. 2E , which is a schematic diagram (5) of the process of the tantalum thin film solar cell module of the present invention. This step is to deposit the electrode layer 170 on the conversion layer units 140 a , 140 b , 140 c , 140 d . The electrode layer 170 may be selected from nickel, gold, silver, titanium, copper, palladium, and aluminum to extract electrical energy, and has a thickness of between 200 nm and 600 nm. The process of the electrode layer 170 is selected from any one of the group consisting of a vapor deposition method, a sputtering method, a plating method, a chemical vapor deposition method, and a printing method. In a preferred embodiment of the invention, an aluminum metal film is used and has a thickness between 500 nm and 900 nm.

Step 360: Forming a plurality of electrode units.

Please refer to FIG. 2F, which is a schematic diagram (6) of the process of the tantalum thin film solar cell module of the present invention. This step is performed by performing a third laser process at a second distance 180 from the second laser incision 160. A plurality of electrode units 170a, 170b, 170c, and 170d are formed by the third laser cut 190. The width W2 of the second distance 180 is preferably between 50 um and 110 um in the embodiment, and the width L3 of the third laser cut 190 is preferably 30 um to 110 um. In order to form a modular battery, the electrode units 170a, 170b, and 170c are electrically connected to the conductive film units 120b, 120c, and 120d through the second laser cuts 180, respectively. It should be noted that the connection between each unit battery can be in series or parallel. The laser wavelength of the third laser process is selected from one of a second frequency and a third frequency of the YAG laser, wherein the metal electrode is more reflective to the YAG laser having the second frequency, but However, at a lower cost, a YAG laser having a double wavelength of laser light is used in the preferred embodiment of the present invention. From the relative relationship between the wavelength and the absorption coefficient of the three kinds of ruthenium films shown in Fig. 4, it can be judged that if the transparent conductive film of the lower layer cannot be destroyed during the stripping process, the 532 nm green solid-state laser should be selected. good. It should be noted that excessive laser energy is easy to remove the ruthenium film layer, but it will cause poor photoelectric properties of the transparent conductive film, and recrystallization of the sidewall of the ruthenium film layer, resulting in large leakage current, resulting in component or module efficiency. reduce.

Step 370: Remove a portion of the conversion layer unit outside the substrate.

Please refer to FIG. 2G, which is a schematic diagram of the process of the thin film solar cell module of the present invention (7). This step performs the fourth laser process to remove the conversion layer units 140a, 140d and the electrode unit outside the substrate 110. 170a, 170d to form a space 210. The interval 210 distinguishes the power generation area 230. The power generation region 230 is composed of a plurality of unit solar cells in series and parallel. The solar cells connected in series are formed of conductive film units 120a, 120b, 120c, and 120d, conversion layer units 140a, 140b, 140c, and 140, and electrode units 170a, 170b, and 170c. It should be noted that, for each unit cell, the sum of the widths of the first laser slit width, the second laser slit width, the third laser slit width, the first distance 150, and the second distance 180 is referred to as the invalid region width. The width is less than 5% of the width of each unit cell in the embodiment of the present invention, that is, the width of the ineffective area in all of the unit cells is less than 5% of the width of the entire power generating area 230 to minimize the area of the ineffective area. The laser wavelength of the fourth laser process is selected from one of the second frequency and the third frequency of the YAG laser. In the embodiment of the invention, the YAG laser with the laser wavelength of the double frequency is used. The width L4 of the space 210 is between 50 um and 5000 um in this embodiment.

Referring to Figure 5, there is shown a cross-sectional view of a tantalum thin film solar cell according to a first embodiment of the present invention. In the present embodiment, the collector electrode 410 is electrically connected to the conductive film units 120a, 120d to take out electrical energy. The collector electrode 410 can be selected from a metal foil. In a preferred embodiment, the collector electrode 410 is a copper foil and is electrically connected to the conductive film units 120a, 120d by solder.

For the purpose of insulating the outer side of the substrate, the fifth embodiment of the present invention may further include performing a fifth laser process for removing portions of the conductive film units 120a, 120d, the conversion layer units 140a, 140d, and the outside of the substrate 110. The electrode units 170a, 170d are formed to form an edge region surrounding the power generating region 230 for insulating the outermost portion of the substrate 110. Or the transparent conductive film 120, the photoelectric conversion layer 140, and the electrode layer 170 other than the etching process 210 are removed to achieve the same purpose. In a preferred embodiment of the present invention, the distance L5 of the interval 220 generated by the fifth laser process is between 50 um and 5000 um in the embodiment of the present invention, wherein the laser wavelength of the fifth laser process is It is selected from one of the second frequency and the third frequency of the YAG laser. In a preferred embodiment, a YAG laser having a double wavelength of laser light is used.

It should be noted that the laser energy density used in the embodiments of the present invention is between 10 J/cm ² and 30 J/cm ² , and the laser pulse width is between 10 nsec and 30 nsec. The relative movement speed of the substrate 110 and the laser is between 3.5 um/min and 80 mm/sec, and the transparent conductive films 120a, 120b, 120c, 120d, the conversion layer units 140a, 140b, 140c, 140d, and the electrodes The isolation of the layers 170a, 170b, 170c, 170d after cutting is between 1 M and 1.5 MΩ.

Referring now to Figure 6, there is shown a cross-sectional view of a tantalum thin film solar cell according to a second embodiment of the present invention. The laser cutting method used in the second embodiment is different from the first embodiment in that the fourth laser process in the first embodiment is omitted, and the fifth laser process in the first embodiment is omitted. Instead, the power generation region 230 is separated by the interval 220 at which it is generated. In the second embodiment, the sum of all the first laser slit width, the second laser slit width, the third laser slit width, the first distance, and the second distance in the power generating region 230 is also smaller than the power generation. The area 230 is 5% wide to achieve an optimum ineffective area width.

It should be noted that the second embodiment is different from the first embodiment in that the collector electrode 410 is electrically connected to the electrode units 170a and 170c to extract electric energy, so that the tantalum thin film solar cell 500 of the second embodiment can be compared. The tantalum thin film solar cell 400 of the first embodiment reduces a laser process to save process cost.

It should be noted that the laser process in the embodiment of the present invention needs to be matched with the cleaning process to perform the action of removing the dust generated by the laser cutting during or after the execution of the laser process to avoid contamination of the substrate caused by dust, and Recrystallization in the laser cutting path to form a short circuit.

In summary, the manufacturing method of the tantalum thin film solar cell module according to the present invention has a plan of better ineffective area width to improve module current and overall power production capacity, and thus has high commercial value and can be widely applied.矽 Thin film solar cell industry.

While the present invention has been described in its preferred embodiments, it is not intended to limit the scope of the invention, and various modifications and changes can be made without departing from the spirit and scope of the invention. As explained above, various modifications and variations can be made without departing from the spirit of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

110. . . Substrate

120. . . Transparent conductive film

120a. . . Conductive film unit

120b. . . Conductive film unit

120c. . . Conductive film unit

120d. . . Conductive film unit

130. . . First laser incision

140. . . Photoelectric conversion layer

140a. . . Conversion layer unit

140b. . . Conversion layer unit

140c. . . Conversion layer unit

140d. . . Conversion layer unit

150. . . First distance

160. . . Second laser incision

170. . . Electrode layer

170a. . . Electrode unit

170b. . . Electrode unit

170c. . . Electrode unit

170d. . . Electrode unit

180. . . Second distance

190. . . Third laser incision

210. . . interval

220. . . interval

230. . . Power generation area

400. . .矽Thick film solar cell

410. . . Collecting electrode

500. . .矽Thick film solar cell

1 is a flow chart showing a method of manufacturing a thin film solar cell module of the present invention.

2A is a schematic view showing the process of the thin film solar cell module of the present invention (1).

2B is a schematic view showing the process of the thin film solar cell module of the present invention (2).

2C is a schematic view showing the process of the thin film solar cell module of the present invention (3).

2D is a schematic view of the process of the tantalum thin film solar cell module of the present invention (4).

FIG. 2E is a schematic view showing the process of the thin film solar cell module of the present invention (5).

FIG. 2F is a schematic view showing the process of the thin film solar cell module of the present invention (6).

Fig. 2G is a schematic view showing the process of the thin film solar cell module of the present invention (7).

Figure 3 is a graph showing the relationship between the wavelength of zinc oxide and the absorption coefficient of a transparent conductive film material.

Fig. 4 is a graph showing the relationship between absorption coefficient and wavelength of amorphous germanium, microcrystalline germanium and single crystal germanium.

Fig. 5 is a cross-sectional view showing a tantalum thin film solar cell according to a first embodiment of the present invention.

Figure 6 is a cross-sectional view showing a tantalum thin film solar cell according to a second embodiment of the present invention.

110. . . Substrate

120a. . . Conductive film unit

120b. . . Conductive film unit

120c. . . Conductive film unit

120d. . . Conductive film unit

130. . . First laser incision

140a. . . Conversion layer unit

140b. . . Conversion layer unit

140c. . . Conversion layer unit

140d. . . Conversion layer unit

150. . . First distance

160. . . Second laser incision

170a. . . Electrode unit

170b. . . Electrode unit

170c. . . Electrode unit

180. . . Second distance

190. . . Third laser incision

210. . . interval

220. . . interval

230. . . Power generation area

400. . .矽Thick film solar cell

410. . . Electrode unit

Claims (9)

A method for manufacturing a tantalum thin film solar cell module, comprising the steps of: depositing a transparent conductive film on a substrate; performing a first laser process to form the transparent conductive film into a plurality of conductive films by using a first laser cut a unit; depositing a photoelectric conversion layer on the conductive film units; performing a second laser process to form the plurality of photoelectric conversion layers by a second laser cut at a first distance from the first laser cut a conversion layer unit; depositing an electrode layer on the conversion layer units; performing a third laser process at a second distance from one of the second laser cuts, the electrode being cut by a third laser cut Forming a plurality of electrode units, and the electrode units are electrically connected to the conductive film units respectively through the second laser cut; and performing a fourth laser process to remove portions of the outer side of the substrate Forming a space between the layer unit and the electrode units, and the interval distinguishes a power generating region, wherein the power generating region has a plurality of solar cells connected in series, and wherein the first laser The width of the mouth, the second laser slit width, the slit width of the third laser, the first distance and the second distance is less than 5% of the width of the power generation area. The method of manufacturing a thin film solar cell module according to claim 1, wherein the photoelectric conversion layer is composed of a germanium-based material. The method for manufacturing a thin film solar cell module according to claim 1, wherein the laser wavelength of the first laser process is selected from one of a fundamental frequency of the YAG laser and a second frequency multiplication. The method of manufacturing a thin film solar cell module according to claim 1, wherein the laser wavelength of the second laser process is selected from one of a second frequency and a third frequency of the YAG laser. The method for manufacturing a thin film solar cell module according to claim 1, wherein the laser wavelength of the third laser process is selected from one of a second frequency and a third frequency of the YAG laser. The method of manufacturing a thin film solar cell module according to claim 1, wherein the laser wavelength of the fourth laser process is selected from one of a second frequency and a third frequency of the YAG laser. The method for manufacturing a thin film solar cell module according to claim 1, further comprising the steps of: forming a collector electrode on the conductive film units, the collector electrode electrically connecting the conductive film units. The method for manufacturing a thin film solar cell module according to claim 1, further comprising the steps of: performing a fifth laser process for removing the outermost portion of the substrate, the conductive film unit, the conversion layer unit, and The electrode unit is formed to surround an edge region of the power generating region for insulating the outermost portion of the substrate. The method for manufacturing a thin film solar cell module according to claim 1, wherein the laser wavelength of the fifth laser process is selected from one of a second frequency and a third frequency of the YAG laser.