Cadmium telluride power generation glass and preparation method thereof

Abstract

The invention discloses cadmium telluride power generation glass and a preparation method thereof, and relates to the technical field of preparation of cadmium telluride power generation glass. The cadmium telluride power generation glass comprises a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer and a back electrode layer which are stacked in sequence, the back contact layer is made of a P-type heavily-doped ZnTe material, and light can be incident from the glass substrate so that the glass substrate can generate power. The invention also provides a preparation method of the power generation glass, which specifically comprises the following steps: providing the glass substrate, arranging the front electrode layer on the glass substrate, and depositing the window layer on the front electrode layer; depositing an absorption layer on the window layer, and depositing a back contact layer on the absorption layer to obtain a first prefabricated member; performing heat treatment on the first prefabricated part to obtain a second prefabricated part; and depositing a back electrode layer on the back contact layer of the second prefabricated member to obtain a finished product. By arranging the back contact layer between the absorption layer and the back electrode layer, the potential barrier is reduced, and the current density, the cell filling factor and the conversion efficiency are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and particularly relates to a cadmium telluride power generation glass and a preparation method thereof. Background Art

[0002] As a II-VI group compound semiconductor, cadmium telluride (CdTe) is a direct bandgap semiconductor with a bandgap width of 1.46 eV, which is very close to the optimal bandgap width required for solar cells. It has a high solar absorption coefficient. In the range of the solar radiation spectrum where the energy is higher than the bandgap width of CdTe, a 1-μm-thick CdTe thin film can effectively absorb 99% of it. Therefore, it has a very high absorption coefficient in the visible light wavelength range, high conversion efficiency and low cost, but relatively low in the long-wave band.

[0003] Conventional cadmium telluride solar cells generally include the following structures in the order of light incidence direction. See Figure 2 : a glass substrate 7, a TCO film layer 8, a CdSe window layer 9, a CdTe absorption layer 10, and a back electrode 11. Among them, the CdTe absorption layer is in direct contact with the back electrode. The work function of the P-type CdTe layer is 5.7 eV, which is higher than the work functions of most metal materials. When a metal material is directly prepared on the surface of the CdTe thin film as the back electrode, a Schottky barrier will be formed at the interface between CdTe and the metal, hindering the transport of photo-generated carriers and reducing the performance of the battery.

[0004] To obtain excellent back contact characteristics, it is necessary to require that the metal oxide contact layer itself can well transport the photo-generated current generated by light in the battery. Affected by factors such as the energy band positions of CdTe and the metal oxide, the transport of current at the back contact in the metal oxide depends on the defects formed by oxygen vacancies in the material. However, an increase in the oxygen vacancy concentration will reduce the work function of the metal oxide material, causing a hole barrier to re-form on the back of the cadmium telluride. On the contrary, if the oxygen hole concentration in the metal oxide is reduced, the work function of the metal oxide material will increase, which will inhibit the formation of the back hole barrier, but the transport of photo-generated current in the molybdenum oxide layer will deteriorate. Therefore, it is very difficult to obtain excellent back contact characteristics by using a metal oxide material as the back contact layer of the cadmium telluride power generation glass.

[0005] In summary, the existing cadmium telluride power generation glass has the following defects: the direct contact between the metal back electrode and the cadmium telluride film layer results in a relatively high barrier, generating additional impedance and reducing the performance of the cadmium telluride power generation glass. Summary of the Invention

[0006] The object of the present invention is to solve the problem that the direct contact between the metal back electrode of the existing cadmium telluride power generation glass and the cadmium telluride film layer results in a high barrier, reducing the performance of the cadmium telluride power generation glass. The present invention sets a back contact layer between the absorption layer and the back electrode layer, enabling the metal back electrode to form an ohmic contact with cadmium telluride, reducing the additional impedance, lowering the barrier, and increasing the current density, cell fill factor, and conversion efficiency.

[0007] In order to achieve the above object, the present invention specifically adopts the following technical solutions:

[0008] A cadmium telluride power generation glass for generating electricity under the action of light, comprising a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer, and a back electrode layer stacked in sequence. The back contact layer is a P-type heavily doped ZnTe material, and the light can be incident from the glass substrate to enable the cadmium telluride power generation glass to generate electricity.

[0009] Further, the doping metal material of the ZnTe material is any one or more of Ag, Cu, Hg, and Au.

[0010] Further, the doping metal materials of the ZnTe material are Ag and Cu.

[0011] Further, the doping ratio of the Ag metal element in the ZnTe material is 100 ppm to 1% wt, and the doping ratio of the Cu metal element is 100 ppm to 3% wt.

[0012] Further, the thickness of the back contact layer is 10 to 30 nm.

[0013] The present invention also provides a preparation method of the cadmium telluride power generation glass based on the above, comprising the following steps:

[0014] S1. Provide a glass substrate, set a front electrode layer on the glass substrate, deposit a window layer on the front electrode layer; deposit an absorption layer on the window layer, deposit a back contact layer on the absorption layer, and obtain a first preform;

[0015] S2. Heat-treat the first preform to obtain a second preform;

[0016] S3. Deposit a back electrode layer on the back contact layer of the second preform to obtain a finished product.

[0017] Further, in step S1, physical vapor deposition is used to deposit the back contact layer.

[0018] Further, in step S2, the heat treatment is carried out in an inert atmosphere or under vacuum.

[0019] Further, in step S2, the temperature of the heat treatment is 240 to 300 °C.

[0020] Further, in step S2, the heat treatment time is 10 to 60 minutes.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1. In the existing back contact layer, most are metal oxide layers. The metal oxide layer will form a potential barrier at the back electrode, thus hindering the transport of carriers, resulting in an increase in the carrier recombination probability, and further leading to a decrease in the fill factor of the battery.

[0023] However, for the cadmium telluride power generation glass provided by the present invention, the back contact layer is set as a P-type heavily doped ZnTe material, which can play a role in reducing the potential barrier, improving the ohmic contact with the back electrode, increasing the current density, providing a channel for the transport of carriers, reducing its recombination probability, increasing the battery fill factor, and greatly improving the conversion efficiency, thus significantly enhancing the power generation performance.

[0024] It can be seen that the cadmium telluride power generation glass in this case has a higher current density and fill factor compared with the cadmium telluride power generation glass without a back contact layer. On the other hand, compared with the cadmium telluride power generation glass with a back contact layer of a metal oxide layer in the prior art, the cadmium telluride power generation glass of the present invention can effectively improve the ohmic contact with the back electrode, increase the current density and fill factor, and effectively improve the conversion efficiency.

[0025] 2. The preparation method of the cadmium telluride power generation glass provided by the present invention is simple and easy to operate, and the control of each parameter is relatively simple, making the manufacturing difficulty low and facilitating large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the cadmium telluride power generation glass provided by the present invention.

[0027] Reference numerals in the drawings: 1 - glass substrate, 2 - front electrode layer, 3 - window layer, 4 - absorption layer, 5 - back electrode layer, 6 - back contact layer.

[0028] Figure 2 It is a schematic structural diagram of a conventional cadmium telluride power generation glass.

[0029] Reference numerals in the drawings: 7 - glass substrate, 8 - TCO film layer, 9 - CdSe window layer, 10 - CdTe absorption layer, 11 - back electrode.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention.

[0031] Accordingly, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the scope of protection of the present invention. Detailed Description of the Invention

[0032] A cadmium telluride power generation glass, please refer to Figure 1 , which is used for generating electricity under the action of light. The cadmium telluride power generation glass includes a glass substrate 1, a front electrode layer 2, a window layer 3, an absorption layer 4, a back contact layer 6, and a back electrode layer 5 that are sequentially stacked. The back contact layer 6 is a P-type heavily doped ZnTe material, and the light can enter from the glass substrate to enable the cadmium telluride power generation glass to generate electricity.

[0033] It can be understood that most of the existing back contact layers are metal oxide layers. The metal oxide layer will form a potential barrier at the back electrode, thereby hindering the transport of carriers, increasing the probability of carrier recombination, and further reducing the fill factor of the battery.

[0034] In this case, the back contact layer is set as a P-type heavily doped ZnTe material, which can play the role of reducing the potential barrier, improving the ohmic contact with the back electrode, increasing the current density, providing a channel for the transport of carriers, reducing the probability of their recombination, increasing the battery fill factor, and greatly improving the conversion efficiency, thereby significantly improving the power generation performance.

[0035] It can be seen that the cadmium telluride power generation glass in this case has a higher current density and fill factor compared with the cadmium telluride power generation glass without a back contact layer (such as Figure 2 this conventional cadmium telluride power generation glass). On the other hand, compared with the cadmium telluride power generation glass with a back contact layer of a metal oxide layer in the prior art, the cadmium telluride power generation glass of the present invention effectively improves the ohmic contact with the back electrode, increases the current density and fill factor, and effectively improves the conversion efficiency.

[0036] In some embodiments of the present invention, the doped metal material of the ZnTe material is any one or more of Ag, Cu, Hg, and Au.

[0037] Specifically, the doping ratio of each element is 200 ppm to 5% wt. Specifically, the doping ratio of each element is 0.002 wt% to 5 wt%.

[0038] In some embodiments of the present invention, the doped metal materials of the ZnTe material are Ag and Cu.

[0039] It can be understood that the Ag and Cu co-doped back contact layer thin film can play a role in reducing the potential barrier, improving the ohmic contact with the back electrode, increasing the current density, providing a channel for the transport of carriers, reducing their recombination probability, increasing the cell fill factor, and greatly improving the conversion efficiency.

[0040] The Ag and Cu co-doped back contact layer thin film reacts with CdTe in the Te-rich layer or the absorption layer through the Ag and Cu elements in the thin film to form a telluride degenerated semiconductor that is beneficial to the ohmic contact of the absorption layer CdTe, and can form a thin Schottky barrier with the back electrode. Photo-generated carriers can then reach the back electrode through the tunneling effect through the CdTe surface.

[0041] In some embodiments of the present invention, the doping ratio of Ag metal element in the ZnTe material is 100 ppm to 1% wt, and the doping ratio of Cu metal element is 100 ppm to 3% wt.

[0042] Specifically, the doping ratio of Ag metal element is 0.001 wt% to 1 wt%, and the doping ratio of Cu metal element is 0.001 wt% to 3 wt%. The doping amount of Ag metal element is 0.001 wt% to 1 wt% of the ZnTe material, and the doping amount of Cu metal element is 0.001 wt% to 3 wt% of the ZnTe material.

[0043] In some embodiments of the present invention, the thickness of the back contact layer is 10 to 30 nm.

[0044] In some embodiments of the present invention, the front electrode layer is a TCO film layer. The window layer is a CdSe window layer. The absorption layer is a CdTe absorption layer.

[0045] The present invention also provides a preparation method of the cadmium telluride power generation glass based on the above, including the following steps:

[0046] S1. Provide a glass substrate, set a front electrode layer on the glass substrate, deposit a window layer on the front electrode layer; deposit an absorption layer on the window layer; deposit a back contact layer on the absorption layer to obtain a first preform;

[0047] S2. Heat-treat the first preform to obtain a second preform;

[0048] S3. Deposit a back electrode layer on the back contact layer of the second preform to obtain a finished product.

[0049] It can be understood that through heat treatment, the reaction and diffusion of the back contact layer are promoted, and the contact characteristics can be improved.

[0050] In some embodiments of the present invention, in step S1, physical vapor deposition is used to deposit the back contact layer.

[0051] In certain embodiments of the present invention, in step S1, the deposition substrate temperature is required to be 150 - 280 °C.

[0052] In certain embodiments of the present invention, in step S2, the heat treatment is carried out in an inert atmosphere or under vacuum.

[0053] In certain embodiments of the present invention, in step S2, the temperature of the heat treatment is 240 - 300 °C.

[0054] In certain embodiments of the present invention, in step S2, the time of the heat treatment is 10 - 60 minutes.

[0055] It can be understood that a preparation method of cadmium telluride power generation glass provided by the present invention has a simple preparation method, is easy to operate, and the control of each parameter is relatively simple, making the manufacturing difficulty low and facilitating large-scale application.

[0056] Example 1

[0057] This example provides a sample 1 of cadmium telluride power generation glass. According to the light incident direction, the cadmium telluride power generation glass includes a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer, and a back electrode layer that are sequentially stacked. The back contact layer is a P-type heavily doped ZnTe material with a thickness of 10 - 30 nm. The doping metal materials of the ZnTe material are co-doped with Ag and Cu. The doping ratio of the Ag metal element is 100 ppm - 1% wt, and the doping ratio of the Cu metal element is 100 ppm - 3% wt. The light can be incident from the glass substrate to enable the cadmium telluride power generation glass to generate electricity.

[0058] Preparation method of sample 1:

[0059] S1. Provide a glass substrate, and the deposition substrate temperature is required to be 150 - 280 °C. Set a front electrode layer on the glass substrate, deposit a window layer on the front electrode layer; deposit an absorption layer on the window layer; deposit a back contact layer on the absorption layer by physical vapor deposition to obtain a first preform;

[0060] S2. Perform heat treatment on the first preform to obtain a second preform. The heat treatment is carried out in an inert atmosphere or under vacuum. The temperature of the heat treatment is 240 - 300 °C, and the time of the heat treatment is 10 - 60 minutes;

[0061] S3. Deposit a back electrode layer on the back contact layer of the second preform to obtain sample 1.

[0062] Example 2

[0063] This embodiment provides a sample 2 of cadmium telluride photovoltaic glass. In the direction of light incidence, the cadmium telluride photovoltaic glass sequentially includes: a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer, and a back electrode layer. The back contact layer is a P-type heavily doped ZnTe material with a thickness of 10 - 30 nm. The doping metal material of the ZnTe material is Ag doping, and the doping ratio of Ag metal element is 100 ppm - 1% wt.

[0064] The preparation method of sample 2 is the same as that of Example 1 and will not be elaborated here.

[0065] Example 3

[0066] This embodiment provides a sample 3 of cadmium telluride photovoltaic glass. In the direction of light incidence, the cadmium telluride photovoltaic glass sequentially includes: a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer, and a back electrode layer. The back contact layer is a P-type heavily doped ZnTe material with a thickness of 10 - 30 nm. The doping metal material of the ZnTe material is Cu doping, and the doping ratio of Cu metal element is 100 ppm - 3% wt.

[0067] The preparation method of sample 3 is the same as that of Example 1 and will not be elaborated here.

[0068] Comparative Example 1

[0069] This embodiment provides a comparative example 1 of cadmium telluride photovoltaic glass. In the direction of light incidence, the cadmium telluride photovoltaic glass sequentially includes: a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer, and a back electrode layer. The back contact layer is MoO x .

[0070] Test Example 1

[0071] 1. Test Design

[0072] Measure the conversion efficiency, short-circuit current density, and fill factor of the cadmium telluride photovoltaic glass prepared in the sample examples of Examples 1 - 3 and the comparative example respectively.

[0073] 2. Test Results

[0074] The measured results are shown in Table 1.

[0075] Table 1

[0076]

[0077] 3. Result Analysis

[0078] It can be seen from the above table that for Examples 1 - 3 using the back contact layer of this case, the conversion efficiency is above 12.7%, while for Comparative Example 1 using the conventional metal oxide layer, the conversion efficiency is only 10.4%.

[0079] For Examples 1-3 using the back contact layer of this case, the short-circuit current density is all above 24.3 mA / cm 2 For Comparative Example 1 using a conventional metal oxide layer, the short-circuit current density is only 23.5 mA / cm 2 .

[0080] For Examples 1-3 using the back contact layer of this case, the fill factor is all above 55.4%, while for Comparative Example 1 using a conventional metal oxide layer, the fill factor is only 45.9%.

[0081] It can be seen that the cadmium telluride power generation glass of this case effectively improves the ohmic contact with the back electrode, increases the current density and fill factor, and effectively improves the conversion efficiency.

[0082] However, by horizontally comparing Example 1, Example 2, and Example 3, it can be seen that Example 1 with Ag and Cu co-doping has the highest conversion efficiency, short-circuit current density, and fill factor. Followed by Example 3 with Cu doping, and the worst is Example 2 with Ag doping.

[0083] In summary, the cadmium telluride power generation glass of the present invention has a higher current density and fill factor compared to the cadmium telluride power generation glass without a back contact layer. Compared with the cadmium telluride power generation glass with a metal oxide layer back contact layer in the prior art, the cadmium telluride power generation glass of the present invention effectively improves the ohmic contact with the back electrode, increases the current density and fill factor, effectively improves the conversion efficiency, and has superiority.

[0084] Test Example 2

[0085] 1. Test design

[0086] Explore the P-type heavily doped ZnTe material of the back contact layer of the cadmium telluride power generation glass, where the ZnTe material is co-doped with Ag and Cu, and the doping ratio of Ag metal element and Cu metal element.

[0087] Set multiple groups of samples with different doping ratios of Ag and Cu.

[0088] Specifically: the doping ratio (molar ratio) of Ag to Cu in Experimental Group 1 is 1:1, the ratio of Ag to Cu in Experimental Group 2 is 1:100, the ratio of Ag to Cu in Experimental Group 3 is 1:1000, and the ratio of Ag to Cu in Experimental Group 4 is 1:10000. Measure the conversion efficiency, short-circuit current density, fill factor, and maximum attenuation rate of the cadmium telluride power generation glass in each experimental group respectively.

[0089] 2. Test results

[0090] Table 2

[0091] Experimental Group 1 Experimental Group 2 Experimental Group 3 Experimental Group 4 Ratio of Ag to Cu 1:1 1:100 1:1000 1:10000 Conversion Efficiency (%) 14.5 16.2 15.3 14.8 <![CDATA[Short - circuit current density (mA / cm 2 )]]> 24.3 26.7 25.2 24.8 Fill Factor (%) 59％ 70.20％ 65.1％ 63.7％ Maximum Decay Rate (% / year) 1.3％ 0.4％ 0.7％ 0.8％

[0092] 3. Result Analysis

[0093] Referring to Table 2, it can be seen that when the doping ratio of Ag to Cu is 1:100, the conversion efficiency is the highest, reaching 16.2%, which is better than other groups.

[0094] At this ratio, the short - circuit current density of the cadmium telluride power - generating glass can reach 26.7 mA / cm 2 , presenting a peak value.

[0095] Meanwhile, at this ratio, the fill factor of the cadmium telluride power - generating glass can reach 70.20%, which is higher than the other three groups.

[0096] At this ratio, the maximum attenuation rate of the cadmium telluride power - generating glass is only 0.4%, which is much lower than the other three groups.

[0097] It can be seen that after exploring the doping ratio of Ag to Cu, when the doping ratio of Ag to Cu is 1:100, all parameters reach the best values. It can be seen that the ratio of 1:100 is a relatively preferred value in this case.

[0098] In summary, according to the exploration of Experiment 1, the cadmium telluride power - generating glass of the present invention has a higher current density, fill factor, and conversion efficiency compared with the cadmium telluride power - generating glass without a back - contact layer.

[0099] Through the exploration of Experiment 2, a relatively preferred doping ratio was found.

[0100] And during the exploration process, 4 experimental groups were set up, and their performance parameters were compared with the control group of Experiment 1. It can be seen that the performances of Experimental Groups 1 - 4 are all better than those of the conventional cadmium telluride power - generating glass in the control group.

[0101] It can be seen that the cadmium telluride power - generating glass in this case has strong superiority.

[0102] The above embodiments are only one implementation manner of the present invention, and its description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A cadmium telluride power generation glass for generating electricity under the action of light, Characterized in that: It includes a glass substrate, a front electrode layer, a window layer, an absorption layer, a back contact layer, and a back electrode layer that are sequentially stacked. The back contact layer is a P-type heavily doped ZnTe material, and the light can be incident from the glass substrate to enable the cadmium telluride power generation glass to generate electricity.

2. A cadmium telluride power generation glass according to claim 1, Characterized in that, The doping metal material of the ZnTe material is any one or more of Ag, Cu, Hg, and Au.

3. A cadmium telluride power generation glass according to claim 2, Characterized in that, The doping metal material of the ZnTe material is Ag and Cu.

4. A cadmium telluride power generation glass according to claim 3, Characterized in that, In the ZnTe material, the doping ratio of Ag metal element is 100 ppm to 1% wt, and the doping ratio of Cu metal element is 100 ppm to 3% wt.

5. A cadmium telluride power generation glass according to claim 1, Characterized in that, The thickness of the back contact layer is 10 - 30 nm.

6. A preparation method of a cadmium telluride power generation glass according to any one of claims 1 - 5, Characterized in that, It includes the following steps: S1. Provide a glass substrate, set a front electrode layer on the glass substrate, deposit a window layer on the front electrode layer; deposit an absorption layer on the window layer, deposit a back contact layer on the absorption layer, and obtain a first preform; S2. Heat-treat the first preform to obtain a second preform; S3. Deposit a back electrode layer on the back contact layer of the second preform to obtain a finished product.

7. A preparation method of a cadmium telluride power generation glass according to claim 6, Characterized in that, In step S1, physical vapor deposition is used to deposit the back contact layer.

8. A preparation method of a cadmium telluride power generation glass according to claim 6, Characterized in that, In step S2, the heat treatment is carried out in an inert atmosphere or under vacuum.

9. A preparation method of a cadmium telluride power generation glass according to claim 6, Characterized in that, In step S2, the temperature of the heat treatment is 240 - 300 °C.

10. A preparation method of a cadmium telluride power generation glass according to claim 6, Characterized in that, In step S2, the time of the heat treatment is 10 - 60 minutes.

Images