CN205122595U - Space silicon solar cell's antireflection coating - Google Patents

Abstract

The utility model relates to a space silicon solar cell's antireflection coating comprises two -layer antireflection coating at least, wherein has at least the one deck to adopt the refracting index to be less than 1.4 nano -material. Reduce the reflection loss of light, obtained space efficient silicon solar cell, improved solar cell's photoelectric conversion efficiency, low refracting index nano -material antireflection coating's design has advantages such as technology conveniently realizes, application prospect is extensive, provides effectual preparation parameter and foundation in theory for space silicon solar cell antireflection coating's preparation.

Description

A kind of antireflective coating of space Si solar cells

Technical field

The utility model relates to a kind of antireflective product, particularly a kind of antireflective coating of space Si solar cells.

Background technology

Current solar photovoltaic industry is in the low ebb of development, and tracing it to its cause is that its efficient energy conversion is low, and high cost causes; and along with coal, the scarcity day by day of the fossil fuel resources such as oil, the pressure of environmental protection in addition; development solar energy, the regenerative resources such as wind energy are extremely urgent.Relative to wind energy, the regenerative resources such as underground heat, it is extremely wide that solar energy has energy distributional region, in use can not produce the feature of any pollution.By solar panel, solar energy is converted into electric energy, the important channel that the mankind solve energy problem will inevitably be become.But compared with other battery, the photoelectric conversion efficiency of solar cell is lower.Therefore, improve its efficiency be for a long time people endeavour always solve problem, and the key factor affecting battery efficiency be exactly battery to the utilance inciding its surface light, namely battery is to the spectral response inciding its surperficial each wavelength light.We know, silicon is indirect transition shaped material, and its absorption coefficient is low, make the light loss of solar cell fail to keep an appointment 1/3 with the time in the reflection of silicon face.The principle of reflection of ear is pinched according to phenanthrene, the reflection that single or multiple lift antireflective coating (its refractive index is less) can reduce incident light is prepared at battery surface, increase transmission, increase effective absorption of photon, incident light subnumber is more, spectral response is larger, and the photoelectric conversion efficiency of battery is also higher.Therefore, to space silicon solar battery antireflective film and spectral response research be solar cell design, preparation in key.

At present, a large amount of work that studies in great detail has been done in the design, preparation etc. of home and abroad to antireflecting film of monocrystalline silicon solar battery, single, double even three layers of antireflective coating have been widely applied in the preparation of single crystal silicon solar cell all, and particularly double layer antireflection coating has achieved good anti-reflective effect in the application.But due to the restriction of conventional antireflection film material refractive index, make the anti-reflective effect of antireflective coating conventional at present weakened.This is because the refractive index of general conventional antireflection film material is all greater than 1.4.Nano material utilizes material little after nanoscale, the unusual appearance occurred due to dimensional effect, skin effect and macroscopic quantum effect and the new material developing out.In recent years, nanometer interpolation, compound and packaging technology, to material science research, comprise material modification, new material synthesis and new diseases, create material impact.Relevant research shows, nanometer technology, as technology of quantum dots, nanometer surface modification technology etc., can promote the competitiveness of solar energy generation technology.For antireflective coating, the key improving material reflects efficiency is first to obtain has less refraction materials.And for general material, its refractive index is all larger, and refractive index between 1 ~ 1.4 material almost do not have, this just must adopt nano material and nanometer technology, improves the microstructure of material, thus reduce refractive index.Along with the development of nanometer technology, the nano material of preparation refractive index below 1.4 is made to become possibility, though have much about the research of anti-reflection film of solar cell, but still lack the research that low-index material (being less than 1.4) is designed at space Si solar cells antireflection film system both at home and abroad.

Utility model content

The utility model is the problem for how reducing space Si solar cells reflection, propose a kind of antireflective coating of space Si solar cells, the structure of the antireflection film system of low-refraction nano material, this structure is by using low-refraction nano material, reflectivity is reduced, anti-reflective effect is obvious, thus solves the antireflective problem of space Si solar cells in use procedure preferably.

The technical solution of the utility model is: a kind of antireflective coating of space Si solar cells, is at least made up of two-layer antireflective coating, wherein have at least one deck adopt refractive index lower than 1.4 nano material.

Described antireflective coating is double-deck, and ground floor is nano material, refractive index n ₁be 1.1≤n ₁≤ 1.3, film thickness d ₁for 110nm, the second layer is conventional refractive material, refractive index n ₂be 2.3, film thickness d ₂for 64nm.

Described antireflective coating is three layers, and ground floor is nano material, refractive index n ₁be 1.3, film thickness d ₁for 66nm, the second layer is conventional refractive material, refractive index n ₂be 1.46, film thickness d ₂for 50nm, third layer is conventional refractive material, refractive index n ₃be 2.3, film thickness d ₃for 60nm.

The beneficial effects of the utility model are: the antireflective coating of the utility model space Si solar cells, low-refraction nano material is have employed in antireflection film system structure, by computer simulation, space Si solar cells antireflective coating is designed, devise two, the trilamellar membrane adopting low-refraction nano material respectively, the best film system parameter of optimization, obtain minimum Weighted Average Method, the preparation for space Si solar cells antireflective coating provides theoretic foundation.

Accompanying drawing explanation

Fig. 1 conventional refractive materials double-layer film reflectivity R is with wavelength X change curve;

During Fig. 2 conventional refractive material MgF2 (102nm)/TiO2 (49nm)/SiO2 trilamellar membrane, reflectivity is with the change curve of SiO2 layer thickness;

The reflectivity of the double layer antireflection coating of Fig. 3 tri-kinds of different refractivity nano material optimal design is with wavelength change curve chart;

Fig. 4 is that the utility model nano material three layers of antireflective coating reflectivity are with wavelength change curve chart;

Fig. 5 is the reflectivity change curve that the utility model nanometer antireflective coating changes three layers of antireflective coating of second layer material.

Embodiment

Single antireflection film utilizes light there is the principle of interference of phase difference at the both sides place reverberation of antireflective coating and reach anti-reflective effect, and Fresnel formula can be utilized to try to achieve reflectivity.

For assembly of thin films, can appoint wherein and get one deck, each tunic is above equivalent to an interface, each tunic below is also equivalent to an interface, then whole system is equivalent to a monofilm, also can obtain the equivalent fresnel coefficient of assembly of thin films, thus obtain reflectivity.

If the reflectivity properties that the concept introducing optical admittance (Y) under discussion analyzes multilayer optical film is easily.At this moment refractive index is n ₀incident medium apply mechanically Fresnel formula with the interface that m layer is equivalent to a new matrix together with substrate, then can obtain the reflection coefficient r of multilayer dielectric film, r=(n ₀-Y)/(n+Y), and reflectivity is

$R={\left|r\right|}^2={\left|\frac{n_0-Y}{n_0+Y}\right|}^2$

Y=C/B (C: floor parameter in formula; B: parameters of film).Can be obtained by the feature expression of following equivalent optical admittance

$\left[\begin{array}{c}B\\ C\end{array}\right]=\left\{\underset{k=1}{\overset{m}{\Π}}\left[\begin{array}{cc}{\mathrm{cos\δ}}_k& i\left({\mathrm{sin\δ}}_k\right)/n_k\\ {\mathrm{i\η}}_k{\mathrm{sin\δ}}_k& {\mathrm{cos\δ}}_k\end{array}\right]\right\}\left[\begin{array}{c}1\\ n_s\end{array}\right]=\left[\begin{array}{cc}{M}_{11}& M_{12}\\ M_{21}& M_{22}\end{array}\right]\left[\begin{array}{c}1\\ n_s\end{array}\right]$

δ in formula _kequal the phasic difference of k layer and k+1 layer two coherent beam, η _kfor revising admittance, n _kfor kth layer optical film refractive index, d _kfor kth layer optical film thickness, δ _k=2 π n _kd _k/ λ, λ are lambda1-wavelength.N _sbe s layer optical film refractive index (s=1,2 ..., m, s ≠ k).The formula more than provided is the situation of vertical incidence light.

The reflectivity R of film system depends on film layer structure parameter above.Generally, the spectral distribution for vertical incidence and incident light is known, therefore by the adjustment number of stories m of film system and the optical thickness n of each tunic _kd _k(k=1,2 ..., m) obtain minimum reflectivity.

Sunlight is distributed in a larger wave-length coverage, therefore, to solar cell requirement, has good anti-reflective effect, make more incident optical energies enter battery in a wider spectral region.Consider the internal quantum of silicon materials, the silicon solar cell of photovoltaic application needs to have a minimum reflectivity in all visible spectrum (300nm ~ 1100nm) scopes.For making silicon absorb more photon, and being electric energy by these transform light energy, in antireflecting coating design, also will taking into account the spectral characteristic of sunlight while considering silicon materials internal quantum, for space solar cell it is considered that AM0 solar spectrum.So, by the internal quantum of single wavelength points reflectivity, incident photon flux, silicon materials, the Weighted Average Method in whole spectral region can be calculated:

$R_W=\frac{{\∫}_{{\mathrm{\λ}}_1}^{{\mathrm{\λ}}_2}F\left(\mathrm{\λ}\right)Q\left(\mathrm{\λ}\right)R\left(\mathrm{\λ}\right)d\mathrm{\λ}}{{\∫}_{{\mathrm{\λ}}_1}^{{\mathrm{\λ}}_2}F\left(\mathrm{\λ}\right)Q\left(\mathrm{\λ}\right)d\mathrm{\λ}}$

In formula, F (λ) is incident photon flux, the internal quantum that Q (λ) is silicon, R (λ) for antireflective coating is at the reflectivity of corresponding wavelength point, λ ₁, λ ₂for spectral wavelength bound, λ ₁=300nm, λ ₂=1100nm.

The utility model devises the antireflection film system structure of multiple combination, gives optimized result, and its advantage is: 1. low-refraction nano material is introduced in antireflection film system design by the utility model, reaches good result; 2. design result of the present utility model has the advantages such as technique conveniently realizes, application prospect is extensive, for the preparation of space Si solar cells antireflective coating provides preparation parameter, can be applicable to the field such as solar energy industry field and optical fiber communication, multimedia digital product, IT industry, auto industry, military affairs, aeronautical and space technology

1, conventional material double layer antireflection coating

Conventional refractive materials double-layer film reflectivity R is with wavelength X change curve as shown in Figure 1, and we utilize computer program simulation conventional refractive material MgF respectively ₂/ TiO ₂, SiO ₂/ TiO ₂the reflectivity of duplicature when best film layer thickness with the change curve of wavelength, as shown in Figure 1.For MgF ₂/ TiO ₂duplicature, thickness d (MgF ₂)=100nm, d (TiO ₂during)=62nm, there is minimum Weighted Average Method, R _wmin=1.23%, SiO ₂/ TiO ₂duplicature, thickness d (SiO ₂)=94nm, d (TiO ₂during)=61nm, R _wmin=1.6%, visible, the conventional material duplicature of the nanoscale combined has achieved good anti-reflective effect.

2, conventional material three layers of antireflective coating

Fig. 2 gives conventional refractive material MgF ₂(102nm)/TiO ₂(49nm)/SiO ₂the SiO of three layers of antireflective coating ₂reflectivity change curve during layer thickness variation, SiO in three-dimensional coordinate ₂thickness is the parameter of change, works as SiO ₂when layer thickness is 10nm, this trilamellar membrane has minimum Weighted Average Method, R _wmin=1.55%.Along with SiO ₂the increase reflectivity smallest point of layer thickness moves to long wave direction gradually, and the reflectivity of shortwave direction and visible region is increasing, and this makes anti-reflective effect worse and worse.Calculate, work as SiO ₂layer thickness becomes 15nm respectively, when 20nm, 25nm, 30nm, and R _wvalue be respectively 2.31%, 3.81%, 5.91%, 8.46%, as seen with SiO ₂the increase of layer thickness, Weighted Average Method R _walso increasing gradually, anti-reflective effect is undesirable.

3, nano material double layer antireflection coating

In order to further reduce incident light reflectance, we adopt the nano material of low-refraction to be optimized design as antireflection film material.For duplicature, have employed the antireflection film system that the nano material optimal design of three kinds of different refractivities three kinds is different respectively, anti-reflective effect is also different.As Fig. 3 gives the change curve of reflectivity with wavelength of three kinds of double layer antireflection coatings of optimization.N ₁for the refractive index of ground floor low-refraction nano material, d ₁for its thickness, n ₂for second layer Refractive Index of Material, the material of employing is TiO ₂, d ₂for second layer material thickness.R _wit is the Weighted Average Method calculated.The optimization film system parameter of curve B is n ₁=1.1, d ₁=133nm, n ₂=2.3, d ₂=66nm, calculating Weighted Average Method is R _w=4.74%.The optimization film system parameter of curve C is n ₁=1.2, d ₁=121nm, n ₂=2.3, d ₂=65nm, calculating Weighted Average Method is R _w=2.43%.The optimization film system parameter of curve D is n ₁=1.3, d ₁=110nm, n ₂=2.3, d ₂=64nm, calculating Weighted Average Method is R _w=1.36%.

As seen from the figure, three curves all have minimum reflectivity near 600nm wavelength, and curve D at the reflectivity of each wavelength points all than curve B, C is low, and therefore curve D has best anti-reflective effect.Compared with the design result of the duplicature of employing conventional material, the Weighted Average Method of curve D is lower, utilize the nanometer antireflective coating of the optimization film system parameter of D to have better anti-reflective effect than conventional antireflective coating, if the refractive index of nano material reduced, effect is better.Calculate known, compared with typical bilayer antireflective coating, the nanometer antireflective coating minimum weight average reflectance of optimization reduces 15%.

4, novel nano-material three layers of antireflective coating

For trilamellar membrane, also have employed the antireflection film system that the nano material optimal design of three kinds of different low-refractions three kinds is different respectively.Fig. 4 is the change curve of reflectivity with wavelength of the three kinds of double layer antireflection coatings optimized.Three kinds of film system parameters are respectively, and the optimization film system parameter of curve E is n ₁=1.1, d ₁=96nm, n ₂=1.46, d ₂=85nm, n ₃=2.3, d ₃=61nm, calculating Weighted Average Method is R _w=1.17%.The optimization film system parameter of curve F is n ₁=1.2, d ₁=59nm, n ₂=1.46, d ₂=76nm, n ₃=2.3, d ₃=60nm, calculating Weighted Average Method is R _w=1.25%.The optimization film system parameter of curve G is n ₁=1.3, d ₁=66nm, n ₂=1.46, d ₂=50nm, n ₃=2.3, d ₃=60nm, calculating Weighted Average Method is R _w=1.21%.

As seen from the figure, three curves have less reflectivity respectively near 450nm and 800nm wavelength, and all there are good anti-reflective effect in three kinds of film systems.Compared with the design result of the trilamellar membrane of employing conventional material, adopt the trilamellar membrane Weighted Average Method of nano material lower, adopt the anti-reflective effect of the trilamellar membrane of nano material to be obviously better than conventional material antireflective coating, Weighted Average Method reduces 24.5%.In addition, for conventional material, the Weighted Average Method of trilamellar membrane is higher than duplicature, and after adopting the nano material of low-refraction, trilamellar membrane Weighted Average Method is lower than duplicature, and anti-reflective effect obviously improves.

The reflectivity change curve of Fig. 5 for a change three layers of antireflective coating of second layer material.Ground floor is the nano material of low-refraction, and refractive index is 1.1, and third layer is still TiO ₂, we become the lower MgF of refractive index second layer material ₂.Optimization obtains, and first, second and third layer thickness of this film system is respectively 56nm, when 91nm, 62nm, has minimum weight average reflectance, R _w=1.18%, visible, this trilamellar membrane system also has good anti-reflective effect.

Claims (3)

1. an antireflective coating for space Si solar cells, is at least made up of two-layer antireflective coating, it is characterized in that, wherein have at least one deck adopt refractive index lower than 1.4 nano material.

2. the antireflective coating of space Si solar cells according to claim 1, is characterized in that, described antireflective coating is double-deck, and ground floor is nano material, refractive index n ₁be 1.1≤n ₁≤ 1.3, film thickness d ₁for 110nm, the second layer is conventional refractive material, refractive index n ₂be 2.3, film thickness d ₂for 64nm.

3. the antireflective coating of space Si solar cells according to claim 1, it is characterized in that, described antireflective coating is three layers, and ground floor is nano material, refractive index n ₁be 1.3, film thickness d ₁for 66nm, the second layer is conventional refractive material, refractive index n ₂be 1.46, film thickness d ₂for 50nm, third layer is conventional refractive material, refractive index n ₃be 2.3, film thickness d ₃for 60nm.