N-type nanometer black silicon manufacturing method and solar cell manufacturing method

A solar cell, N-type technology, applied in the direction of nanotechnology, nanotechnology, nanotechnology for materials and surface science, etc., can solve the problems of industrial application obstacles and high cost, and achieve the purpose of reducing corrosion depth, increasing lifespan, Effect of increasing short-circuit current and open-circuit voltage

Active Publication Date: 2015-03-11

ZHEJIANG JINKO SOLAR CO LTD

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However, the high cost of TMAH has cau...

Abstract

The invention discloses an N-type nanometer black silicon manufacturing method and a solar cell manufacturing method. The N-type nanometer black silicon manufacturing method comprises steps that: (1), silicon chips after cleaning react in mixed solution of KOH and isopropanol for 0.5-2 hours, and the reaction temperature is 60-100 DEG C; and (2), the N-type silicon chips treated in the step (1) are put in a silver nanometer particle solution for 20-30 minutes in a standing mode, after drying, corrosion treatment on the treated N-type silicon chips is carried out to acquire the N-type nanometer black silicon. For manufacturing a solar cell, an N+ layer, a silicon nitride layer and an electrode layer are sequentially formed at the front surface of the manufactured N-type nanometer black silicon, after sintering, the N-type nanometer black silicon solar cell is manufactured. The manufactured N-type nanometer black silicon solar cell has properties of low reflectivity and high carrier service life and has the conversion efficiency 2.2% higher than that of a cell manufactured through a routine method.

Application Domain

Material nanotechnologyFinal product manufacture +2

Technology Topic

Silicon nitrideCorrosion +12

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Examples

Experimental program(2)

Example Embodiment

[0045] Example 1

[0046] The preparation method of the N-type nano black silicon of the present embodiment comprises the steps:

[0047] (1) 1.5g polyvinylpyrrolidone (PVP K-30) is dissolved in water, forms 50g base liquid, and the mass concentration of formaldehyde is 0.74% in the base liquid, and the mass concentration of polyvinylpyrrolidone in the base liquid is 3%, to base liquid Add dropwise silver nitrate aqueous solution mass concentration in the liquid to be 1.7%, rapidly inject ammonia water (mass fraction is 0.6ml of the solution of 28%), react 30min under 35 ℃, obtain the solution of silver nanoparticles, then add alcohol and centrifuge four times, obtain silver Nanoparticles, the silver nanoparticles are spherical, and the size (particle diameter) of the silver nanoparticles is 50nm-100nm.

[0048] (2) Put an N-type silicon wafer (N-type Czochralski single-crystal native silicon wafer) with a size of 156mm×156mm into 20mt% KOH solution, react at 80°C for 2min, and remove the damaged layer on the surface of the silicon wafer.

[0049] (3) Put the silicon chip after cleaning into the mixed solution of KOH and isopropanol, wherein the mass concentration of KOH is 3%, and the volume concentration of isopropanol is 7%, react 60min under the condition of 80 ℃, in silicon The sheet surface forms a pyramid structure of uniform size.

[0050] (4) the silicon chip with pyramid structure of step (3) is put into silver nanoparticle solution and left standstill 20min, then dry, the surface structure of the N-type silicon chip that obtains is as follows figure 1.

[0051] The minority carrier lifetime of the N-type silicon wafer at this time is 10.18 μs measured by the minority carrier lifetime tester. Further reflectivity test is carried out, and the obtained reflectivity is as follows Figure 4 As shown in curve a, the reflectance is 13.4%.

[0052] (5) Put the silicon wafer in step (4) into a light-shielding reaction container equipped with an etching solution, and react at room temperature for 3, 4, 5, and 6 minutes respectively. The etching solution is HF, H 2 o 2 The mixed solution with deionized water, the solution ratio is 1:5:10 (volume ratio), and a nano-light trapping structure is formed on the surface of the pyramid, that is, a monocrystalline silicon solar cell texture with low surface reflectivity, that is, N-type Nano black silicon.

[0053] figure 2 It is a scanning electron microscope (SEM) picture of the silicon wafer surface after etching for 4 min. from figure 2 Compared figure 1 It can be seen that after 4 minutes of catalytic corrosion, the porous structure uniformly covers the surface of the N-type silicon wafer, forming a nano-light trapping structure.

[0054] image 3 It is the reflectance spectrum of the silicon wafer under different catalytic etching time, it can be seen that the average reflectance in the wavelength range of 300-1100nm is reduced to below 2.4%. Among them, the reflectivity corresponding to corrosion for 3, 4, 5, and 6 minutes is 2.2%, 1.9%, 2.0%, and 2.3%, respectively.

[0055] The minority carrier lifetime of the N-type nano-black silicon obtained by etching for 4 minutes is 2.73 μs after being tested by a minority carrier lifetime tester.

[0056] (6) Put the silicon chip of step (5) into 65wt% HNO3 solution and place it for 1 min to remove residual silver nanoparticles.

[0057] In this embodiment, gaseous diffusion of phosphorus to form an N+ layer on the front surface, PECVD silicon nitride plating, screen printing and sintering are also carried out according to the existing P-type solar cell production process. However, screen printing should use all-aluminum back printing.

[0058] The solar cell obtained in this embodiment is the nanometer black silicon N+NP solar cell. Under the light intensity of AM 1.5, the electrical properties of the battery were tested by using the cell efficiency sorter, and the test results are shown in Table 1. Among them, Voc is the open circuit voltage, Isc is the short circuit current, FF is the fill factor, η is the conversion efficiency, and τ is the minority carrier lifetime of the silicon wafer after texturing.

[0059] For the convenience of comparison, Table 1 also lists the electrical performance and minority carrier lifetime of existing N+NP solar cells (ie, prior art) under light intensity of AM 1.5. The existing N+NP solar cell refers to an N+NP solar cell with no nano light-trapping structure but only a pyramidal structure on the surface (that is, an N-type silicon wafer etched for 0 min).

[0060] Table 1

[0061]

Example Embodiment

[0062] Example 2

[0063] Same as Example 1, the difference is that the etching time in step (5) is 4min, and the N-type silicon wafer after step (5) is processed by the following process between step (6) and step (7) Make etch corrections:

[0064] Put the N-type silicon chip treated in step (6) into 2wt% NaOH solution and react for 3 minutes, so as to perform etching correction on the nano light-trapping structure obtained in step (5). Then put the silicon chip into 10vol% hydrochloric acid for 2 minutes to remove sodium ions, then clean the silicon chip with deionized water, and then dry it with nitrogen gas.

[0065] The nanometer black silicon N+NP solar cell prepared in Example 2 was tested for various electrical properties of the cell by using a cell efficiency sorter under the light intensity of AM 1.5, and the results are shown in Table 1.

[0066] The minority carrier lifetime of the N-type nano-black silicon prepared in this example is 5.19 μs, and the corresponding reflectivity is as follows: Figure 4 As shown in curve c, the reflectance is 5.4%. For comparison, Figure 4 The reflectance curve of the N-type silicon wafer etched for 4 minutes in Example 1 is also given in , as shown in curve b.

[0067] Comparing the test parameters of the above-mentioned embodiments, it is found that although the reflectance of the silicon wafer after the etching correction will increase correspondingly, it is still lower than 5.5%, and the conversion efficiency of the solar cell after the etching correction is higher than that in the embodiment only. The conversion efficiency of the solar cell corresponding to 4min is 2.2% higher.

PUM

Property	Measurement	Unit
Size	50.0 ~ 100.0	nm
Life expectancy	10.2	µs
Life expectancy	2.73	µs

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AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

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Example Embodiment

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Description & Claims & Application Information

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