Method for improving performance of cadmium telluride solar cell device and solar cell device

Abstract

The invention provides a method for improving the performance of a cadmium telluride solar cell device, which is characterized by comprising the following steps of: preparing a cadmium telluride film semi-finished product; the cadmium telluride thin film semi-finished product comprises a conductive substrate, and an electron transport layer and a cadmium telluride absorption layer which are sequentially deposited on the conductive substrate; preparing a bismuth chloride solution; spin-coating the cadmium telluride absorption layer with a bismuth chloride solution, and then placing the cadmium telluride absorption layer on a heating stage for annealing to obtain a bismuth-doped cadmium telluride thin film; a back contact material is deposited on the bismuth-doped cadmium telluride film, and then a metal electrode layer is evaporated through thermal evaporation. According to the method for improving the performance of the cadmium telluride solar cell device, through the doping method, the open-circuit voltage and the photoelectric conversion efficiency of the cadmium telluride thin-film solar cell can be remarkably improved, and a new technical path is provided for improving the performance of the cadmium telluride thin-film solar cell. The invention also provides a solar cell device.

Description

Technical Field

[0001] The present invention belongs to the field of solar photovoltaic technology, and specifically relates to a method for improving the performance of a cadmium telluride solar cell device and a solar cell device. More specifically, the present invention relates to a method for improving the performance of a cadmium telluride solar cell device, a cadmium telluride solar cell device, and a solar cell. Background Art

[0002] Among renewable energy technologies, solar cells, as a technology that directly converts solar energy into electrical energy, are increasingly attracting widespread attention worldwide. Among them, CdTe (cadmium telluride) thin-film solar cells, as a typical representative of the second generation of solar cells, have become a hot topic of current research due to their high theoretical photoelectric conversion efficiency, low cost, and good stability. The main advantages of CdTe thin-film solar cells are their high absorption coefficient and adjustable band gap, which give them excellent light absorption capabilities in the visible light range. However, despite the many advantages of CdTe thin-film solar cells, their performance improvement still faces many challenges in the actual industrialization process. How to improve the performance of CdTe (cadmium telluride) solar cells has always been a hot topic and difficulty in research in this field. Summary of the Invention

[0003] The present invention aims to provide a method for improving the performance of a cadmium telluride solar cell device and a solar cell device, aiming to provide a solar cell device with higher photoelectric conversion efficiency.

[0004] To achieve the above object, the technical solution adopted by the present invention is to provide a method for improving the performance of cadmium telluride solar cell devices, comprising the following steps:

[0005] preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate;

[0006] preparing a bismuth chloride solution;

[0007] Spin-coating a bismuth chloride solution on the cadmium telluride absorber layer, and then annealing the layer on a hot plate to obtain a bismuth-doped cadmium telluride thin film;

[0008] The back contact material is deposited on the bismuth-doped cadmium telluride film, and then a metal electrode layer is evaporated by thermal evaporation.

[0009] Preferably, the preparation of the bismuth chloride solution comprises: dissolving bismuth chloride in ethylene glycol at a preset concentration, and then performing ultrasonic operation to fully dissolve the bismuth chloride, wherein the preset concentration range of bismuth chloride is 10-60 mM.

[0010] Preferably, bismuth chloride is dissolved in ethylene glycol at a concentration of 60 mM, and then ultrasonicated for 10-60 minutes to fully dissolve the bismuth chloride.

[0011] Preferably, the bismuth chloride solution is spin-coated on the cadmium telluride absorption layer at a rotation speed of 3000-4000 r / s for 25-30 seconds.

[0012] Preferably, the bismuth chloride solution is spin-coated on the cadmium telluride absorption layer, and then placed on a hot stage for annealing, including: the temperature of the hot stage is 100-200°C.

[0013] Preferably, the electron transport layer comprises one or more of SnO2, CdS and CdSe.

[0014] Preferably, the cadmium telluride absorption layer has a thickness of 2-4 μm.

[0015] A solar cell device comprises a product prepared based on the method for improving the performance of a cadmium telluride solar cell device as described in any one of the above items.

[0016] Preferably, a conductive substrate, an electron transport layer, a cadmium telluride absorption layer, a back contact material layer and a metal electrode layer are stacked in sequence from one end to the other end; wherein the cadmium telluride absorption layer is doped with bismuth element.

[0017] Preferably, the thickness of the metal electrode layer is 60-100 nm.

[0018] The beneficial effect of the method for improving the performance of a cadmium telluride solar cell device and the solar cell device provided by the present invention is that: compared with the prior art, the method for improving the performance of a cadmium telluride solar cell device and the solar cell device of the present invention introduce bismuth as a dopant into the cadmium telluride thin film by non-in-situ doping. This method not only overcomes the problems of complex operation and limited dopant selection in traditional doping methods, but also achieves efficient and uniform doping of bismuth elements in the cadmium telluride thin film. At the same time, since bismuth is a non-toxic and environmentally friendly compound, this method also has the advantages of environmental protection and safety. Through the doping method of the present invention, the open circuit voltage and photoelectric conversion efficiency of cadmium telluride thin film solar cells can be significantly improved, providing a new technical path for improving the performance of cadmium telluride thin film solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 (a) shows the open circuit voltage (V OC )’s changing trend;

[0021] Figure 1 (b) The short-circuit current (J) under different Bi doping concentration conditions SC )’s changing trend;

[0022] Figure 1 (c) The change trend of fill factor (FF) under different Bi doping concentration conditions;

[0023] Figure 1 (d) The changing trend of photoelectric conversion efficiency (PCE) under different Bi doping concentration conditions;

[0024] Figure 2 The external quantum efficiency (EQE) curves of the highest cell efficiency without Bi doping and with the optimal Bi concentration doping are shown above;

[0025] Figure 3 (a) X-ray diffraction (XRD) patterns of samples without Bi doping and with the optimal Bi concentration.

[0026] Figure 3 (b) XRD patterns of the samples without Bi doping and with the optimal Bi concentration as mentioned above with the main peaks magnified;

[0027] Figure 4 The open circuit voltage changes of the highest efficiency cell without Bi doping and with the optimal Bi concentration under different light intensities. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] Please also refer to Figures 1 to 4 The present invention now provides a cadmium telluride (CdTe) solar cell device, which includes a conductive substrate, an electron transport layer, a CdTe absorber layer, a back contact material layer, and a metal electrode layer stacked in sequence from one end to the other. The CdTe absorber layer is doped with bismuth (Bi), and more specifically, the surface of the CdTe absorber layer contains Bi.

[0030] In one embodiment of the present invention, a conductive substrate includes a glass substrate and a TCO (Transparent Conducting Oxide) layer coated on the surface of the glass substrate. Specifically, the glass substrate includes one or more of a quartz glass substrate, a soda-lime glass substrate, and an ultra-clear glass substrate. The conductive material used in the TCO layer is a transparent conductive oxide.

[0031] As a specific implementation of an embodiment of the present invention, the electron transport layer includes one or more of SnO2, CdS and CdSe.

[0032] As a specific implementation of the embodiment of the present invention, the back contact material layer includes one or more of anhydrous copper chloride and Cu-doped ZnTe.

[0033] As a specific implementation of the embodiment of the present invention, the metal electrode includes one or more of a gold electrode and a silver electrode.

[0034] As a specific implementation of the embodiment of the present invention, the thickness of the cadmium telluride absorption layer is 2-4 μm.

[0035] A method for improving the performance of a cadmium telluride solar cell device, for preparing a cadmium telluride (CdTe) solar cell device as described in any one of the above, comprising the following steps:

[0036] Step S1, preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate;

[0037] Step S2, preparing a bismuth chloride solution; the specific implementation process of this step is: dissolving bismuth chloride in ethylene glycol at a preset concentration, and then performing an ultrasonic operation to fully dissolve the bismuth chloride, wherein the concentration of bismuth chloride is 10-60mM, and the ultrasonic time is selected in the range of 10-60min.

[0038] Step S3: Spin-coating the bismuth chloride solution on the cadmium telluride absorption layer, and then placing it on a hot plate for annealing to obtain a bismuth-doped cadmium telluride thin film, that is, the surface of the cadmium telluride absorption layer contains Bi element; in this step, the rotation speed is 3000-4000 r / s, the time is 25-30 seconds, and the temperature of the hot plate is 100-200°C.

[0039] Step S4: Deposit a back contact material on the bismuth-doped cadmium telluride film, and then thermally evaporate a metal electrode layer. Specifically, the thickness of the metal electrode layer is 60 nm to 100 nm, preferably 80 nm. The material of the metal electrode layer is gold.

[0040] In any achievable embodiment, the area size of each small battery can be defined by a mask, such as the area size is selected to be 0.105 cm 2 .

[0041] The present invention provides a method for improving the performance of cadmium telluride solar cell devices and a solar cell device. Compared to the prior art, bismuth is introduced as a dopant into a cadmium telluride thin film via an ex-situ doping method. Bi doping can effectively improve the conductivity of the cadmium telluride thin film and is expected to increase carrier concentration. This method not only overcomes the problems of complex operation and limited dopant selection in traditional doping methods, but also achieves efficient and uniform doping of bismuth into the cadmium telluride thin film. Furthermore, since bismuth is a non-toxic and environmentally friendly compound, this method also offers advantages such as environmental friendliness and safety. The doping method of the present invention can significantly improve the open-circuit voltage and photoelectric conversion efficiency of cadmium telluride thin-film solar cells, providing a new technical approach for improving the performance of cadmium telluride thin-film solar cells. Specifically, bismuth doping can reduce non-radiative recombination, thereby improving the collection efficiency of photogenerated carriers, and thus effectively improving the photoelectric conversion efficiency of cadmium telluride solar cells. Traditional cadmium telluride solar cell doping processes are often complex and require special steps to activate the dopant. This not only increases production costs but also limits improvements in doping efficiency. The bismuth doping technology provided by this invention offers advantages such as ease of operation and high tolerance to processing environments. This method can be performed in air, significantly simplifying the doping process. Bismuth doping enhances device stability by optimizing the cell's internal structure, such as reducing defect density and improving grain boundary quality. This helps extend the life of solar cells and reduce maintenance costs.

[0042] Example 1

[0043] A method for preparing a solar cell device comprises the following steps:

[0044] Step S1, preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate;

[0045] Step S2: Deposit the back contact material on the cadmium telluride film, and then use thermal evaporation to deposit a gold layer with a thickness of 80nm as the metal electrode. The area of ​​each small cell can be defined as 0.105cm by the mask. 2 .

[0046] Example 2

[0047] A method for improving the performance of a cadmium telluride solar cell device comprises the following steps:

[0048] Step S1, preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate;

[0049] Step S2: dissolving bismuth chloride in ethylene glycol at a concentration of 20 mM, and then performing ultrasonic operation to fully dissolve the bismuth chloride, wherein the ultrasonic time is 30 minutes.

[0050] Step S3: spin-coating the bismuth chloride solution on the cadmium telluride absorption layer at a rotation speed of 3000 r / s for 30 seconds, and then placing it on a hot plate at 200° C. for annealing to obtain a bismuth-doped cadmium telluride thin film.

[0051] Step S4: Deposit the back contact material on the bismuth-doped cadmium telluride film, and then thermally evaporate a gold layer with a thickness of 80nm as a metal electrode. The area of ​​each small cell can be defined as 0.105cm by the mask. 2 .

[0052] Example 3

[0053] A method for improving the performance of a cadmium telluride solar cell device comprises the following steps:

[0054] Step S1, preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate;

[0055] Step S2: dissolving bismuth chloride in ethylene glycol at a concentration of 60 mM, and then performing ultrasonic operation to fully dissolve the bismuth chloride, wherein the ultrasonic time is 30 min.

[0056] Step S3: spin-coating the bismuth chloride solution on the cadmium telluride absorption layer at a rotation speed of 3000 r / s for 30 seconds, and then placing it on a hot plate at 200° C. for annealing to obtain a bismuth-doped cadmium telluride thin film.

[0057] Step S4: Deposit the back contact material on the bismuth-doped cadmium telluride film, and then thermally evaporate a gold layer with a thickness of 80nm as a metal electrode. The area of ​​each small cell can be defined as 0.105cm by the mask. 2 .

[0058] Example 4

[0059] A method for improving the performance of a cadmium telluride solar cell device comprises the following steps:

[0060] Step S1, preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate;

[0061] Step S2: dissolving bismuth chloride in ethylene glycol at a concentration of 10 mM, and then performing ultrasonic operation to fully dissolve the bismuth chloride, wherein the ultrasonic time is 30 minutes.

[0062] Step S3: spin-coating the bismuth chloride solution on the cadmium telluride absorption layer at a rotation speed of 3000 r / s for 30 seconds, and then placing it on a hot plate at 200° C. for annealing to obtain a bismuth-doped cadmium telluride thin film.

[0063] Step S4: Deposit the back contact material on the bismuth-doped cadmium telluride film, and then thermally evaporate a gold layer with a thickness of 80nm as a metal electrode. The area of ​​each small cell can be defined as 0.105cm by the mask. 2 .

[0064] Instructions attached Figure 1 The trend of the open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency of the cells obtained under different Bi doping conditions is shown. The optimal values ​​of each of these parameters are given in Table 1. It can be seen that with the incorporation of Bi, the open-circuit voltage of the cell significantly increases, but excessive Bi doping leads to a decrease in current. It can be concluded that the optimal Bi doping level is 60 mM. At this optimal Bi doping level, a CdTe solar cell with a photoelectric conversion efficiency of 16.78% was prepared.

[0065]

[0066] Table 1 shows the performance of CdTe batteries obtained with different concentrations of bismuth chloride.

[0067] Instructions attached Figure 2 The EQE curves of the highest efficiency cells without Bi doping and with the optimal Bi concentration are shown. It can be seen that the EQE response of the Bi-doped cell is higher than that of the undoped cell.

[0068] Instructions attached Figure 3 The X-ray diffraction (XRD) patterns of the samples without Bi doping and with the optimal Bi concentration are shown. Figure 3 (b) is the XRD spectrum of the main peak in Figure (a) magnified. It can be clearly seen that the XRD peak shifts to a smaller angle after Bi doping. This is because the atomic radius of Bi atoms is larger. According to the Bragg equation, 2dsinθ=nλ (where d is the crystal plane spacing, θ is the diffraction angle, n is the diffraction order, and λ is the wavelength), when d increases, sinθ decreases, and the corresponding diffraction angle θ shifts to a smaller angle.

[0069] Instructions attached Figure 4The open circuit voltage changes of the highest efficiency cell without Bi doping and the cell with optimal Bi concentration under different light intensities are shown. The fitting is performed by the following formula:

[0070]

[0071] Where q is the elementary charge, I is the light intensity used during the test, k is the Boltzmann constant, T is the absolute temperature, C is a constant, and n is the ideality factor. In principle, the slope of the fitted curve is related to the recombination mechanism. Values ​​of n between 1 and 2 indicate SRH recombination at the interface and in the bulk of the device, while smaller n indicates less SRH recombination. The fitted n for the undoped Bi cell is 1.65, while after doping, it is 1.63, indicating that Bi doping helps reduce recombination in the cell, thereby improving device efficiency.

[0072] The present invention also provides a solar cell, comprising any of the cadmium telluride solar cell devices described above or a cadmium telluride solar cell device prepared by any of the methods described above.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the performance of a cadmium telluride solar cell device, characterized in that: The following steps are involved: preparing a cadmium telluride thin film semi-finished product; the cadmium telluride thin film semi-finished product includes a conductive substrate and an electron transport layer and a cadmium telluride absorption layer sequentially deposited on the conductive substrate; preparing a bismuth chloride solution; Spin-coating a bismuth chloride solution on the cadmium telluride absorber layer, and then annealing the layer on a hot plate to obtain a bismuth-doped cadmium telluride thin film; The back contact material is deposited on the bismuth-doped cadmium telluride film, and then a metal electrode layer is evaporated by thermal evaporation.

2. The method for improving the performance of a cadmium telluride solar cell device according to claim 1, wherein: The method for preparing the bismuth chloride solution includes dissolving bismuth chloride in ethylene glycol at a preset concentration and then performing ultrasonic operation to fully dissolve the bismuth chloride, wherein the preset concentration range of the bismuth chloride is 10-60 mM.

3. The method for improving the performance of a cadmium telluride solar cell device according to claim 2, wherein: Bismuth chloride was dissolved in ethylene glycol at a concentration of 60 mM, and then ultrasonicated for 10-60 min to fully dissolve the bismuth chloride.

4. A method for improving the performance of a cadmium telluride solar cell device according to any one of claims 2 or 3, characterized in that: The bismuth chloride solution is spin-coated on the cadmium telluride absorption layer, comprising: a rotation speed of 3000-4000 r / s and a time of 25-30 seconds.

5. The method for improving the performance of a cadmium telluride solar cell device according to claim 4, wherein: The bismuth chloride solution is spin-coated on the cadmium telluride absorption layer, and then the cadmium telluride absorption layer is placed on a hot stage for annealing, including: the temperature of the hot stage is 100-200 degrees Celsius.

6. The method for improving the performance of a cadmium telluride solar cell device according to claim 1, wherein: The electron transport layer includes one or more of SnO2, CdS and CdSe.

7. A method for improving the performance of a cadmium telluride solar cell device according to any one of claims 1 to 3, characterized in that: The thickness of the cadmium telluride absorption layer is 2-4 μm.

8. A solar cell device, characterized in that: The invention comprises a product prepared based on the method for improving the performance of a cadmium telluride solar cell device according to any one of claims 1 to 7.

9. A solar cell device according to claim 8, characterized in that: A conductive substrate, an electron transport layer, a cadmium telluride absorption layer, a back contact material layer and a metal electrode layer are sequentially stacked from one end to the other; wherein the cadmium telluride absorption layer is doped with bismuth element.

10. The cadmium telluride solar cell device according to claim 9, characterized in that: The thickness of the metal electrode layer is 60-100 nm.

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