CN102610665A - Silicon nanoporous array structured concentrator solar cell and preparation method thereof - Google Patents

Abstract

The invention discloses a silicon nanoporous array structured concentrator solar cell which comprises an Al/Si alloy back electrode, a p + back contact layer, a p-type crystalline silicon layer, an n + contact layer, a SiO2 passivation layer and a front electrode, wherein the p + back contact layer is arranged on the Al/Si alloy back electrode; the p-type crystalline silicon layer is arranged on the p + back contact layer; the n + contact layer is arranged on the p-type crystalline silicon layer, and is provided with a silicon nanoporous array; the SiO2 passivation layer is arranged on the surface of the n + contact layer provided with the silicon nanoporous array; and the front electrode is formed on the n + contact layer in a horizontal-vertical cross mode.

Description

Concentrating silicon nanohole array structure solar cell and preparation method thereof

technical field

The invention relates to a solar cell and a preparation method thereof, in particular to a solar cell with a high-performance light-gathering silicon nanohole array structure and a preparation method thereof.

Background technique

There are two necessary steps for photovoltaic energy conversion through semiconductor pn junctions in solar cells. First, the cell absorbs light, generating electron-hole pairs; then, the device structure separates the electrons and holes, and the electrons flow to the negative electrode while the holes flow to the positive electrode, thereby generating photovoltaic voltage and current. In order to increase light absorption, one method is that most solar cells rely on anti-reflection film to reduce light reflection from the front surface of the cell; another method is to use a pyramid texture on the upper surface of the cell combined with a back surface with optical reflection properties, so that The light transmission route into the battery is lengthened, forming light traps and increasing the open circuit voltage.

The development of nanoscience and technology provides new opportunities for the fabrication of high-efficiency silicon solar cells. Silicon nanostructure materials have significantly better photovoltaic properties than crystalline silicon materials. At present, people pay more attention to solar cells made of hydrogenated nanocrystalline silicon (nc-Si:H) thin films. The nanostructure of silicon grains has a significant quantum confinement effect, which contributes to the increase of the optical absorption spectral range. The hydrogenated nanocrystalline silicon material also has a larger specific surface area, so it has a larger light absorption coefficient and good absorption characteristics. The pn junction of solar cells with silicon nanowire structure grows in the radial direction of the nanowire, and the transport of photogenerated carriers is separated from the direction of light absorption, which has longer minority carrier lifetime and transmission length. At the same time, silicon atoms in silicon nanowires have directional and ordered growth, which can improve their crystal quality, and have a larger specific surface area than silicon nanofilms, and have good light absorption properties. However, the mechanical stability of silicon nanowires is not ideal, and it is easy to collapse, and at the same time, the large resistance and excessive surface recombination consume a large number of photogenerated carriers. Still, nanostructured solar cells have higher cell efficiencies than crystalline silicon itself.

Silicon nanohole array structure battery has the potential to replace silicon nanowire structure battery. The structure takes into account the mechanical stability of crystalline silicon and the light-trapping absorption characteristics of silicon nanostructures, and the nanohole array structure with polygonal symmetrical arrangement has a good light-gathering effect, so it will have better cell efficiency and performance.

Contents of the invention

The main purpose of the present invention is to provide a solar cell with a high-performance light-gathering silicon nanohole array structure and a preparation method thereof. On the premise of being compatible with the existing solar cell preparation process, an innovative silicon nanohole array structure with light concentrating structure is proposed to improve the conversion efficiency of solar cells.

The invention provides a solar cell with a light-gathering silicon nanohole array structure, comprising:

An Al/Si alloy back electrode;

a p ⁺ back contact layer located on top of the Al/Si alloy back electrode;

A p-type crystalline silicon material layer, located on the p ⁺ back contact layer;

An n ⁺ contact layer, located on the top of the p-type crystalline silicon material layer, and a silicon nanohole array is opened on the top of the n ⁺ contact layer;

a _SiO2 passivation layer on the surface of the n ⁺ contact layer with the silicon nanohole array;

A front electrode, crossed horizontally and vertically, is formed on the n ⁺ contact layer.

The present invention also provides a method for preparing a light-gathering silicon nanohole array structure solar cell, comprising the following steps:

Step 1: forming and preparing an n ⁺ contact layer on the upper surface of the p-type crystalline silicon material layer to form a pn ⁺ junction structure;

Step 2: forming a p ⁺ back contact layer on the lower surface of the p-type crystalline silicon material layer;

Step 3: photoetching a photoresist pattern of the silicon nanohole array on the upper surface of the n ⁺ contact layer;

Step 4: filling the Ag metal in the photoresist pattern of the silicon nanohole array, and forming the silicon nanohole array by the method of induced corrosion;

Step 5: on the surface of the n ⁺ contact layer with silicon nanohole arrays, deposit _SiO2 passivation layer;

Step 6: making an Al/Si alloy back electrode on the lower surface of the p ⁺ back contact layer;

Step 7: Fabricate the front electrode on the n ⁺ contact layer by photolithography, etching and metal evaporation stripping.

The beneficial effects of the present invention are:

1. The nanohole array structure solar cell designed by the present invention takes into account both the mechanical stability of crystalline silicon and the light trapping and absorption characteristics of silicon nanostructures, and at the same time, the nanohole array structure with polygonal symmetrical arrangement has a good light concentrating effect, so it will have more Good battery efficiency and performance.

2. The metal catalysis-induced wet etching process used in the present invention to prepare silicon nanopore arrays has simple steps, is easy to prepare regular nanopore arrays in large areas, has little damage to silicon materials, low manufacturing cost, simple steps and high efficiency.

In summary, the method for preparing silicon-based nanopillar arrays provided by the present invention has the above-mentioned obvious beneficial effects compared with the traditional preparation methods. The advantages and practical values mentioned above have made great progress in technology, and have produced easy-to-use and practical effects, so that they are more suitable for practical use.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the following will be described in detail with reference to the accompanying drawings in conjunction with specific embodiments, wherein:

Fig. 1 is a structural schematic diagram of a light concentrating silicon-based nanohole array structure solar cell;

Fig. 2 is the flow chart of preparing light-gathering silicon-based nanohole array structure solar cell provided by the present invention;

Figure 3 is a schematic diagram of the structure of the light-gathering silicon-based nanohole array;

Detailed ways

Please refer to Fig. 1, the present invention provides a solar cell with a light concentrating silicon nanohole array structure, including:

An Al/Si alloy back electrode 101;

A p ⁺ back contact layer 102, located on the Al/Si alloy back electrode 101;

A p-type crystalline silicon material layer 103, located on the p ⁺ back contact layer 102;

An n ⁺ contact layer 104 is located on the p-type crystalline silicon material layer 103, a silicon nanohole array 105 is opened on the n ⁺ contact layer 104, the holes of the silicon nanohole array 105 penetrate the n ⁺ contact layer 104, the The thickness of the n ⁺ contact layer 104 is 100-1000nm, the holes of the silicon nanohole array 105 are periodically arranged in a polygonal symmetrical lattice structure, the aperture of the silicon nanohole array 105 is 100nm-800nm, and the number of periods is 3-5 times Aperture;

A _SiO2 passivation layer 106, located on the surface of the n ⁺ contact layer 104 with the silicon nanohole array 105;

A front electrode 107 is formed horizontally and vertically on the n ⁺ contact layer 104, and the material of the front electrode 107 is Ti/Pd/Ag multilayer metal finger electrode, ITO transparent electrode or graphene transparent electrode.

Please refer to Fig. 2 and refer to Fig. 1 and Fig. 3 in combination, the present invention also provides a method for preparing a light-gathering silicon nanohole array structure solar cell, comprising the following steps:

Step 201: forming and preparing an n ⁺ contact layer 104 on the upper surface of the p-type crystalline silicon material layer 103 to form a pn ⁺ junction structure, and the pn ⁺ junction structure is formed by ion implantation or diffusion;

Step 202: forming a p ⁺ back contact layer 102 on the lower surface of the p-type crystalline silicon material layer 103;

Step 203: On the upper surface of the n ⁺ contact layer 104, a photoresist pattern of the silicon nanohole array 105 is photoetched. The holes of the silicon nanohole array 105 are periodically arranged in a polygonal symmetrical lattice structure, as shown in FIG. 3 . Shape 301, octagon 302 or decagon 303, etc., the aperture of silicon nanohole array 105 is 100nm-800nm, the number of cycles is 3-5 times the aperture, the periodic hole array pattern of this silicon nanohole array 105 adopts nanometer Imprint technology, DUV lithography, femtosecond laser maskless lithography or electron beam lithography;

Step 204: Fill Ag metal in the photoresist pattern of the silicon nanohole array 105, and form the silicon nanohole array 105 by an induced corrosion method, the holes of the silicon nanohole array 105 penetrate the n ⁺ contact layer 104, the n ⁺ The thickness of the contact layer 104 is 100-1000nm, and the process of the Ag metal lattice-induced corrosion of the silicon material is as follows: (a) using HF: _AgNO3 mixed solution to deposit a layer of uniform Ag particles in the periodic hole pattern of the light-gathering structure; (b) Use HF:H ₂ O ₂ mixed solution to anisotropically etch holes under the induction of Ag, and deionized water to stop etching; (c) Then use HNO ₃ :H ₂ O to remove Ag particles, deionized water flushing;

Step 205: Deposit a _SiO2 passivation layer 106 on the surface of the n ⁺ contact layer 104 where the silicon nanohole array 105 is opened;

Step 206: Fabricate an Al/Si alloy back electrode 101 on the lower surface of the p ⁺ back contact layer 102, and the alloy temperature is 450°C;

Step 207: Through photolithography, corrosion and metal evaporation stripping, fabricate the front electrode 107 on the n ⁺ contact layer 104, the material of the front electrode 107 is Ti/Pd/Ag multilayer metal finger electrode, ITO transparent electrode or graphene A transparent electrode, which forms an ohmic contact with the n ⁺ contact layer 104 through annealing.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. optically focused silicon nano hole array structure solar battery comprises:

One Al/Si alloy back electrode;

One p ⁺Back contact, be positioned at Al/Si alloy back electrode above;

One p type crystal silicon material layer is positioned at p ⁺Above the back contact;

One n ⁺Contact layer, be positioned at p type crystal silicon material layer above, this n ⁺Have the silicon nano hole array above the contact layer;

One SiO ₂Passivation layer is positioned at the n that has the silicon nano hole array ⁺The surface of contact layer;

Electrode before one intersects to form in n anyhow ⁺On the contact layer.

2. optically focused silicon nano hole array structure solar battery according to claim 1, wherein n is run through in the hole of silicon nano hole array ⁺Contact layer, this n ⁺The thickness of contact layer is 100-1000nm.

3. optically focused silicon nano hole array solar cells structure according to claim 2, wherein the hole of silicon nano hole array is pressed polygon symmetry dot matrix structural cycle and is arranged, and the aperture of silicon nano hole array hole is 100nm-800nm, and periodicity is 3-5 aperture doubly.

4. optically focused silicon nano hole array solar cells structure according to claim 1, wherein the material of preceding electrode is Ti/Pd/Ag multiple layer metal finger electrode, ito transparent electrode or Graphene transparency electrode.

5. the preparation method of an optically focused silicon nano hole array structure solar battery comprises the steps:

Step 1: form preparation one deck n at p type crystal silicon material layer upper surface ⁺Contact layer forms pn ⁺Junction structure;

Step 2: form p at p type crystal silicon material layer lower surface ⁺Back contact;

Step 3: at n ⁺Make the photoresist figure of silicon nano hole array on the contact layer upper surface by lithography;

Step 4: Ag is metal filled in the photoresist figure of silicon nano hole array, through inducing corroding method, form the silicon nano hole array;

Step 5: be positioned at the n that has the silicon nano hole array ⁺The surface of contact layer, deposit SiO ₂Passivation layer;

Step 6: at p ⁺The back contact lower surface is made Al/Si alloy back electrode;

Step 7: peel off through photoetching, corrosion and evaporation of metal, at n ⁺Electrode before making on the contact layer.

6. the method for preparing optically focused silicon nano hole array structure solar battery according to claim 5, wherein pn ⁺Junction structure adopts ion implantation or diffusion method to form.

7. the method for preparing optically focused silicon nano hole array structure solar battery according to claim 5, wherein n is run through in the hole of silicon nano hole array ⁺Contact layer, this n ⁺The thickness of contact layer is 100-1000nm.

8. the method for preparing optically focused silicon nano hole array structure solar battery according to claim 5; The hole of silicon nano hole array wherein; Press polygon symmetry dot matrix structural cycle and arrange, the aperture of silicon nano hole array hole is 100nm-800nm, and periodicity is 3-5 aperture doubly.

9. the method for preparing optically focused silicon nano hole array structure solar battery according to claim 8, wherein the cycle hole system of battle formations shape of silicon nano hole array adopts nanometer embossing, DUV photoetching, femtosecond laser mask-free photolithography or electron beam lithography to make formation.

10. the method for preparing optically focused silicon nano hole array structure solar battery according to claim 5, wherein the material of preceding electrode is Ti/Pd/Ag multiple layer metal finger electrode, ito transparent electrode or Graphene transparency electrode.

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