Crystalline silicon solar cell based on double hole transport layers

Abstract

The utility model discloses a crystalline silicon solar cell based on double hole transport layers. Comprising a first metal electrode layer, a first transparent electrode layer, an N-type doped polycrystalline silicon electron transport layer, a substrate passivation layer, a silicon substrate, a substrate surface passivation layer, a first hole transport layer, a second hole transport layer, a second transparent electrode layer, a second metal electrode layer and an antireflection layer which are sequentially arranged from bottom to top. The first hole transport layer is a self-assembly molecular layer; the second hole transport layer is an yttrium oxide thin film; the thickness of the second hole transport layer is less than 5 nm. In this way, the crystalline silicon solar cell based on the double hole transport layers is provided. Self-assembly molecules are used as the first hole transport layer, yttrium oxide is used as the second hole transport layer, high-efficiency level matching between the hole transport layers and upper and lower film layers is realized, and the photoelectric conversion efficiency of the device is improved.

Description

Technical Field

[0001] The utility model relates to the field of crystalline silicon solar cells, in particular to a crystalline silicon solar cell based on a double hole transport layer. Background Art

[0002] Solar energy is a highly regarded clean energy source, which has the advantages of rich resources and low cost. Photovoltaic cells are one of the most effective ways to convert solar energy into electrical energy, and industrialization technologies for solar cells such as monocrystalline silicon and polycrystalline silicon have been relatively mature. In recent years, new crystalline silicon solar technologies have become a research hotspot in the field of photovoltaic technologies and have received extensive attention.

[0003] For crystalline silicon-based solar cells, high-quality wafers are now common, and the efficiency potential of such cells largely depends on the effectiveness of their selective carrier contacts. Most of the contact layers used in industrial production are based on highly doped silicon, and its disadvantages are as follows: it may bring negative effects, such as Auger recombination or parasitic absorption, which depends on whether the dopant diffuses into the absorption material or is added to the silicon layer outside the absorption material. Given the application of crystalline silicon solar cells on the scale of millions of kilowatts, finding alternative contact solutions that can bring potential advantages in terms of performance, cost, processing convenience or stability is of extremely high relevance.

[0004] Existing new crystalline silicon solar cells often use P-type doped polysilicon or metal oxides such as molybdenum oxide and vanadium oxide as hole transport layers. Although the number of examples of successfully achieving hole-selective transport in these material families is increasing rapidly, the efficiency of their best solar cells is still relatively low at present, and the highest efficiency is only about 22%. If these contact layers are to be considered for industrial applications, there are still many challenges. The main problem is that the thickness of these hole transport layers is generally relatively thick, resulting in relatively large parasitic absorption losses on the light-incident surface of the battery, thereby reducing the photocurrent that the battery can generate. At the same time, it is difficult to form an efficient match between the existing hole transport layer and the crystalline silicon passivation layer and the electrode at the same time, so it is easy to generate a relatively large contact resistance and affect the device efficiency.

[0005] Therefore, it is necessary to study a new technical solution to solve the above problems. Summary of the Utility Model

[0006] To address the deficiencies and drawbacks of the aforementioned prior art, the present utility model provides a crystalline silicon solar cell based on a double hole transport layer, which provides a crystalline silicon solar cell based on a double hole transport layer. This double hole selection layer can achieve efficient hole transport at an ultra-thin thickness; compared with other hole transport layers, the double hole selection layer of the present invention has significantly reduced parasitic absorption losses; at the same time, compared with a single self-assembled molecular layer, the double hole selection layer of the present invention can have a low contact resistance with the crystalline silicon passivation layer and the electrode, forming an efficient match and improving the cell efficiency.

[0007] To achieve the above object, the present utility model adopts the following technical solutions:

[0008] A crystalline silicon solar cell based on a double hole transport layer, comprising a first metal electrode layer, a first transparent electrode layer, an N-type doped polycrystalline silicon electron transport layer, a substrate passivation layer, a silicon substrate, a substrate surface passivation layer, a first hole transport layer, a second hole transport layer, a second transparent electrode layer, a second metal electrode layer, and an antireflection layer, which are sequentially arranged from bottom to top;

[0009] The first hole transport layer is a self-assembled molecular layer; the second hole transport layer is a yttrium oxide thin film; the thickness of the second hole transport layer is less than 5 nm.

[0010] As a preferred solution, the thickness of the first hole transport layer is 0.1 - 5 nm.

[0011] As a preferred solution, the thickness of the second hole transport layer is 0.5 nm or 1 nm or 1.5 nm.

[0012] As a preferred solution, the first hole transport layer is prepared by spin coating or evaporation.

[0013] As a preferred solution, the second hole transport layer is prepared by evaporation.

[0014] As a preferred solution, the self-assembled molecular layer is a self-assembled molecular layer formed based on molecular self-assembly; the molecule is at least one of 2PACz, MeO-2PACz, and MeO-4PACz.

[0015] Compared with the prior art, the present utility model has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solutions, it mainly provides a crystalline silicon solar cell based on a double hole transport layer; a self-assembled molecule is used as the first hole transport layer, and yttrium oxide is used as the second hole transport layer to achieve an efficient energy level match between the hole transport layer and its upper and lower film layers, improving the photoelectric conversion efficiency of the device.

[0016] The double hole transport layer of the present invention has a lower contact resistance compared to the single-layer self-assembled molecular hole transport layer. Therefore, in terms of device performance, devices using the double hole transport layer all have higher fill factors and photoelectric conversion efficiencies.

[0017] The present invention also optimizes the thickness of the second hole transport layer in the double hole transport layer, enabling the double hole transport layer of the present invention to have more matching energy levels and hole transport efficiencies with the upper and lower film layers; the optimized solution of the present invention also has a higher photoelectric conversion efficiency compared to the traditional solution.

[0018] To more clearly elaborate on the structural features and effects of the present utility model, the following will combine the accompanying drawings with specific embodiments to detail the present utility model. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a crystalline silicon solar cell in Embodiments 1 - 3 of the present utility model;

[0020] Figure 2 It is a schematic structural diagram of a crystalline silicon solar cell in Embodiment 4 of the present utility model.

[0021] Description of the Reference Numerals in the Drawings:

[0022] 110, the first metal electrode layer; 111, the first transparent electrode layer; 112, the N-type doped polycrystalline silicon electron transport layer; 113, the substrate passivation layer; 114, the silicon substrate; 115, the substrate surface passivation layer; 116, the first hole transport layer; 117, the second hole transport layer; 210, the second transparent electrode layer; 211, the second metal electrode layer; 212, the antireflection layer. Detailed Embodiments

[0023] The following will combine the accompanying drawings to clearly and completely describe the technical solutions in the present embodiment of the present utility model. Obviously, the described embodiments are only the preferred embodiments of the present utility model.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0026] Referring to the attached Figures 1 to 2 , a crystalline silicon solar cell based on a double hole transport layer, the structure from bottom to top is successively a first metal electrode layer 110, a first transparent electrode layer 111, an N-type doped polycrystalline silicon electron transport layer 112, a substrate passivation layer 113, a silicon substrate 114, a substrate surface passivation layer 115, a first hole transport layer 116, a second hole transport layer 117, a second transparent electrode layer 210, a second metal electrode layer 211, and an antireflection layer 212. Its manufacturing steps are as follows:

[0027] Prepare a substrate passivation layer 113 on the back of the silicon substrate 114;

[0028] Prepare an N-type doped polycrystalline silicon electron transport layer 112 on the surface of the substrate passivation layer 113; the substrate passivation layer 113 is preferably prepared by plasma enhanced chemical vapor deposition;

[0029] Prepare a first transparent electrode layer 111 on the surface of the N-type doped polycrystalline silicon electron transport layer 112; the first transparent electrode layer 111 is preferably prepared by magnetron sputtering;

[0030] Prepare a first metal electrode layer 110 on the surface of the first transparent electrode layer 111; the first metal electrode layer 110 is prepared by evaporation or screen printing;

[0031] Prepare a substrate surface passivation layer 115 on the surface of the silicon substrate 114;

[0032] Prepare a first hole transport layer 116 on the surface of the substrate surface passivation layer 115;

[0033] Prepare a second hole transport layer 117 on the surface of the first hole transport layer 116; the first hole transport layer 116 is prepared by solution method or evaporation;

[0034] Prepare a second transparent electrode layer 210 on the second hole transport layer 117;

[0035] Prepare a second metal electrode layer 211 on the surface of the second transparent electrode layer 210; the second transparent electrode layer 210 is preferably prepared by magnetron sputtering;

[0036] A anti-reflection layer 212 is prepared on the surface of the second metal electrode layer 211; the second metal electrode layer 211 is prepared by evaporation coating or screen printing;

[0037] Wherein: the first hole transport layer 116 is made by self-assembled molecular layer, and spin coating method can be used. Specifically: first, prepare a precursor solution containing self-assembled molecules, uniformly coat the self-assembled molecular precursor solution on the surface of the substrate passivation layer 113, the spin coating speed is 1200 - 6000 rpm, the spin coating time is 20 - 120 s, and the anti-solvent titration time is 10 - 50 s after the start of the rotation speed. After the spin coating is completed, an annealing operation is carried out, the annealing temperature is 50 - 150 °C, and the annealing time is 5 - 40 min; the first hole transport layer 116 can also be prepared by evaporation coating method, evaporate the self-assembled molecular powder onto the surface of the hole transport layer, and the evaporation coating vacuum degree is between 1×10 -4 -3×10 -4 Pa, and the evaporation coating temperature is 200 - 700 °C. The prepared thickness of the first hole transport layer 116 is 0.1 - 5 nm.

[0038] The second hole transport layer 117 is made of ultrathin yttrium metal oxide and is prepared by evaporation coating plus self-oxidation method. First, evaporate yttrium metal onto the surface of the first hole transport layer 116, the evaporation coating vacuum degree is 1×10 -4 -5×10 -4 Pa, the evaporation coating temperature is 500 - 800 °C, the evaporation rate is 0.05 - 1 Å / S, and the controlled thickness is 0 - 5 nm. After the evaporation is completed, place the film in the air and oxidize it for 0 - 60 min to form a yttrium oxide film.

[0039] It should be noted that: the self-assembled molecular layer is an existing substance, and the self-assembled molecular layer has been publicly disclosed in public materials such as CN110311042B, CN112133867B, CN113173923B, CN114716476B, etc.

[0040] Furthermore: the self-assembled molecules are at least one of 2PACz, Meo-2PACz, Meo-4PACz; the precursor material of the second hole transport layer 117 is metal yttrium (Yb);

[0041] The first transparent electrode layer 111 and the second transparent electrode layer 210 are made of at least one of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO);

[0042] The first metal electrode layer 110 and the second metal electrode layer 211 are made of at least one of silver (Ag), gold (Au), copper (Cu), aluminum (Al), carbon (C);

[0043] The antireflection layer 212 is made of at least one of magnesium fluoride, lithium fluoride (LiF), sodium fluoride (NaF), and silicon dioxide (SiO2).

[0044] Specific comparative examples and examples will be provided below to clearly and completely describe the technical solutions of the present invention. Obviously, the described examples are some examples of the present invention, rather than all examples. All other examples obtained by those of ordinary skill in the art based on the examples of the present invention without creative efforts belong to the scope of protection of the present invention.

[0045] Example 1: A crystalline silicon solar cell based on a double hole transport layer, the structure from bottom to top is successively a first metal electrode layer 110, a first transparent electrode layer 111, an N-type doped polycrystalline silicon electron transport layer 112, a substrate passivation layer 113, a silicon substrate 114, a substrate surface passivation layer 115, a first hole transport layer 116, a second hole transport layer 117, a second transparent electrode layer 210, a second metal electrode layer 211, and an antireflection layer 212. Its manufacturing steps are as follows:

[0046] Step 1: Prepare the substrate passivation layer 113 and the N-type doped polycrystalline silicon electron transport layer 112 successively on the back of the silicon substrate 114, and prepare the substrate surface passivation layer 115 on the surface of the silicon substrate 114.

[0047] Step 2: Prepare the first transparent electrode layer 111; using the magnetron sputtering method, place the sample in the magnetron sputtering equipment, set the ITO target, control the power to 60W, the running time to 1.5h, and the layer film thickness to 100nm;

[0048] Step 3: Prepare the first metal electrode layer 110; using the evaporation method, place the substrate sample on the mask plate, put it into the evaporation chamber, and perform evaporation when the evaporation vacuum degree is 2×10 -4 Pa, adjust the evaporation voltage to the evaporation temperature, control the evaporation rate at 2.5 Å / S, evaporate silver onto the layer film, and the thickness is 200nm;

[0049] Step 4: Prepare the first hole transport layer 116; the self-assembled molecular hole transport layer uses the evaporation method, evaporate the MeO-2PACz powder onto the surface of the substrate surface passivation layer 115, and the evaporation vacuum degree is 1×10 -4 Pa, and the evaporation temperature is 200°C. The thickness of the prepared first hole transport layer 116 is 2nm.

[0050] Step 5: Prepare the second hole transport layer 117; using the evaporation method, place the substrate sample on the mask plate, put it into the evaporation chamber, and wait for the evaporation vacuum degree to be 1×10 -4Evaporation coating is carried out at 1 Pa. The evaporation voltage is adjusted until the evaporation temperature reaches 800 °C, and the evaporation rate is controlled at 0.1 Å / S. Yttrium metal is evaporated onto the film to a thickness of 0.5 nm. Then the sample is placed in the air for self-oxidation for 5 minutes to form a 0.5 nm yttrium oxide (YbOx) film.

[0051] Step 6: Prepare the second transparent electrode layer 210; similar to the preparation of the first transparent electrode layer 111, set the IZO target, control the power at 50 W, the operation time at 1 h, and the film thickness at 100 nm;

[0052] Step 7: Prepare the second metal electrode layer 211; similar to the preparation of the first metal electrode layer 110, with a different mask template and a thickness of 100 nm;

[0053] Step 8: Prepare the antireflection layer 212; using the evaporation coating method, control the evaporation rate at 2 Å / S, and evaporate magnesium fluoride onto the film to a thickness of 100 nm.

[0054] Example 2: Preparation of a crystalline silicon solar cell based on 1 nm yttrium oxide as the second hole transport layer 117.

[0055] This Example 2 is basically the same as Example 1, except that the thickness of the yttrium oxide layer in Step 5 is changed to 1 nm.

[0056] Example 3: Preparation of a crystalline silicon solar cell based on 1.5 nm yttrium oxide as the second hole transport layer 117.

[0057] This Example 3 is basically the same as Example 1, except that the thickness of the yttrium oxide layer in Step 5 is changed to 1.5 nm.

[0058] Example 4: Preparation of a crystalline silicon solar cell based on no yttrium oxide as the second hole transport layer 117;

[0059] This Example 4 is basically the same as Example 1, without Step 5.

[0060] Using a solar simulator, a standard solar light intensity calibration is performed, and a long-term IV test is carried out on the example device with an area of 1.0 cm2. The starting voltage is set at 0.8 V, the cut-off voltage at 0 V, and the range at 100 mA. The results are retained to two decimal places, and the test results are shown in Table 1; 。

[0061] The design focus of the present utility model is mainly to provide a crystalline silicon solar cell based on a double hole transport layer; using self-assembled molecules as the first hole transport layer and preparing ultrathin metal yttrium oxide as the second hole transport layer to achieve efficient energy level matching between this hole transport layer and its upper and lower film layers, thereby improving the photoelectric conversion efficiency of the device.

[0062] Examples 1, 2, 3 and Example 4. The double hole transport layer of the present invention has a lower contact resistance compared to the single-layer self-assembled molecular hole transport layer. Therefore, in terms of device performance, devices using the double hole transport layer all have higher fill factors and photoelectric conversion efficiencies.

[0063] The present invention has also optimized the thickness of the second hole transport layer in the double hole transport layer. Comparing Examples 1, 2, and 3, when the thickness is 1 nm, the double hole transport layer has more matching energy levels and hole transport efficiency with the upper and lower film layers. This is reflected in the fact that the device in Example 2 has a higher fill factor than the devices in Example 1 and Example 3. At the same time, the optimized solution of the present invention has superior performance compared to the traditional solution, which is reflected in the fact that the photoelectric conversion efficiency of the device in Example 2 is higher than that of the device in Example 4.

[0064] The above is only a preferred embodiment of the present utility model, and does not impose any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model still fall within the scope of the technical solution of the present utility model.

Claims

1. A crystalline silicon solar cell based on a double hole transport layer, characterized in that: It includes a first metal electrode layer, a first transparent electrode layer, an N-type doped polysilicon electron transport layer, a substrate passivation layer, a silicon substrate, a substrate surface passivation layer, a first hole transport layer, a second hole transport layer, a second transparent electrode layer, a second metal electrode layer, and an antireflection layer, which are arranged successively from bottom to top; The first hole transport layer is a self-assembled molecular layer; the second hole transport layer is a yttrium oxide thin film; the thickness of the second hole transport layer is less than 5 nm.

2. The crystalline silicon solar cell based on a double hole transport layer according to claim 1, wherein: The thickness of the first hole transport layer is 0.1 - 5 nm.

3. The crystalline silicon solar cell based on a double hole transport layer according to claim 2, wherein: The thickness of the second hole transport layer is 0.5 nm or 1 nm or 1.5 nm.

4. The crystalline silicon solar cell based on a double hole transport layer according to claim 2, characterized in that: The first hole transport layer is prepared by spin coating or evaporation.

5. The crystalline silicon solar cell based on a double hole transport layer according to claim 3, wherein: The second hole transport layer is prepared by evaporation.

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