CN101471214A - Diamond thin-film solar cell and method for producing the same - Google Patents

Abstract

The invention relates to a solar cell in the technical field of space energy, in particular to a solar cell using a special-structured diamond film and a preparation method thereof. The main structure of this diamond thin-film solar cell includes a cathode and an anode: the cathode structure is: a pyramid-shaped diamond cone with a size of 3-4 μm in a large number of uniformly distributed small holes on the surface of crystalline silicon, combined with a metal layer to form a cathode, A layer of black body heat absorbing material is added to the back of the cathode, and the flat metal is used as the anode. The working principle of a solar cell is to use a concentrating device to condense sunlight onto the blackbody heat absorbing material on the back of the cathode, and heat the cathode to above 1000°C, so that a large number of electrons are emitted from the tip of the small cone. Next, electrons flow to the metal anode to form an electric current. The diamond thin film battery involved in the invention can increase the photoelectric conversion efficiency to 50%, can withstand high temperatures above 500°C without damage, and is resistant to space radiation.

Description

A kind of diamond thin film solar cell and preparation method thereof

technical field

The invention relates to a solar cell in the technical field of space energy, in particular to a solar cell using a diamond film with a special structure.

Background technique

Solar energy is an inexhaustible treasure house of renewable energy on the earth. The energy projected by the sun to the surface of the earth within 40 minutes is equivalent to the sum of the annual energy consumption of the whole world. Therefore, if solar energy can be fully utilized, the future of mankind will be guaranteed. The idea of human beings to utilize solar energy has a long history. At first, it was converted into thermal energy for utilization. Later, the discovery of the photovoltaic effect made it possible to convert solar energy into electrical energy, thus providing hope for solving the problem of the earth's energy depletion.

Experts predict that solar power generation will account for 50% of the world's total power generation by 2030. Therefore, vigorously developing the solar cell industry is a great cause that is conducive to reducing environmental pollution and benefiting mankind. Solar cells will also become the future energy source of mankind. star of hope.

Judging from the current development status, due to the limitation of the price of monocrystalline silicon materials and the manufacturing process of monocrystalline silicon cells, it is very difficult to significantly reduce the cost of monocrystalline silicon solar cells, which will hinder the further development of solar cells. Promote apps.

Contents of the invention

The object of the present invention is to provide a solar cell using a diamond film with a special structure as a cathode.

The purpose of the present invention can be achieved through the following technical measures:

A large number of evenly distributed pyramid-shaped diamond cones with a scale of 3 to 4 μm grow on the metal cathode, and the density of the cones is on the order of ten million per ^cm2 area; under the action of an electric field, the field emission of the cone tip is used The effect emits electrons, and by heating the cathode to a temperature above 1000°C, the number of emitted electrons is greatly increased, and after reaching the anode, a current is formed.

The purpose of the present invention can also be achieved through the following technical measures:

(1) Using chemical etching method or laser direct writing method, a large number of uniformly distributed small holes with a diameter of about 5 μm are processed on the surface of the silicon substrate, and the hole depth is 4 to 5 μm. The small holes are arranged in a square on the surface of the silicon substrate , the hole spacing is about 10 μm, and the number of small holes per ^cm2 area is on the order of tens of millions;

(2) Using microwave plasma chemical vapor deposition (MPECVD) to grow a diamond film on a silicon substrate, the working gases are hydrogen (H ₂ ), methane (CH ₄ ) and oxygen (0 ₂ ); the deposition parameters are: substrate The temperature is 1000° C., the microwave power is 3.5 kW, the deposition chamber pressure is 5 kPa, the flow rate of hydrogen is 200 sccm, the flow rate of methane is 8 sccm, and the flow rate of oxygen is 1 sccm. A small pyramid-shaped diamond cone will grow in the small hole, and the scale of the small cone can be changed by controlling the growth time, so that the size of the bottom edge of the cone can be controlled within the range of 3-4 μm;

(3) Add a metal layer on the back of the silicon substrate with pyramid-shaped diamond cones as the cathode, add a layer of black body heat-absorbing material on the metal layer, and combine it with the metal anode, and apply an electric field between the two poles during operation to form Diamond thin film solar cells.

The purpose of the present invention can also be achieved through the following technical measures:

Using a concentrating device, the sunlight is concentrated on the black body heat absorbing material on the back of the cathode, and the cathode is heated to 1000°C. Due to the good thermal conductivity of diamond, the temperature of the tip of the small cone will also be close to 1000°C, and the energy gap of diamond will increase. Electrons also transition from the valence band to the conduction band due to thermal oscillations due to the reduction in heat. Under the action of an applied electric field, a flow of electrons from the cathode to the anode is generated.

The current crystalline silicon solar cells have been commercialized, but have insurmountable shortcomings, including low conversion efficiency, low cell temperature and low ability to withstand space radiation.

The photoelectric conversion efficiency of the diamond thin film battery involved in the present invention can be increased to 50%, and diamond can withstand high temperatures above 500°C without damage, and diamond is the most resistant to space radiation, so it will not be damaged when used in space affected by cosmic rays. In addition, diamond has the highest hardness, so it is not easy to wear, and it also has the fastest heat dissipation, which can quickly dissipate heat energy. These superior properties make diamond thin film solar cells have good development prospects.

The biggest difference between diamond solar cells and current silicon solar cells is that the former uses the "thermoelectric effect", while the latter uses the "photoelectric effect". The former can use lower solar heat, so its power generation efficiency is higher than that of silicon solar cells. In addition, the diamond tip also provides a path without resistance in vacuum, so the flow of electrons will be smoother than that of silicon semiconductors, and the waste heat generated is smaller. , which is another reason why its energy efficiency can be improved.

Description of drawings

Figure 1 is a microscopic topography diagram of the surface of the solar cell cathode;

Fig. 2 is a schematic diagram of the working principle of the solar cell structural machine;

Fig. 3 is a small cone structure diagram.

Detailed ways

The diamond thin-film solar cell in the present invention is mainly made up of the blackbody heat-absorbing layer on the cathode, the anode and the cathode, wherein the anode has no difference from the anode of a common solar cell, and the cathode is a diamond film with a large number of pyramid-shaped small cones on the metal layer , under the action of an electric field and high temperature, a large number of electrons are emitted from the tip of the small cone and reach the anode to form a current.

The fabrication process of diamond thin film solar cells is as follows:

(1) Using chemical etching method or laser direct writing method, a large number of uniformly distributed small holes with a diameter of about 5 μm are processed on the surface of the silicon substrate, and the hole depth is 4 to 5 μm. The small holes are arranged in a square on the surface of the silicon substrate , the hole spacing is about 10 μm, and the number of small holes per ^cm2 area is on the order of tens of millions;

(2) Using microwave plasma chemical vapor deposition (MPECVD) to grow a diamond film on a silicon substrate, the working gases are hydrogen (H ₂ ), methane (CH ₄ ) and oxygen (0 ₂ ); the deposition parameters are: substrate The temperature is 1000° C., the microwave power is 3.5 kW, the deposition chamber pressure is 5 kPa, the flow rate of hydrogen is 200 sccm, the flow rate of methane is 8 sccm, and the flow rate of oxygen is 1 sccm. A small pyramid-shaped diamond cone will grow in the small hole, and the scale of the small cone can be changed by controlling the growth time, so that the size of the bottom edge of the cone can be controlled within the range of 3-4 μm;

(3) Add a metal layer on the back of the silicon substrate with pyramid-shaped diamond cones as the cathode, add a layer of black body heat-absorbing material on the metal layer, and combine it with the metal anode, and apply an electric field between the two poles during operation to form Diamond thin film solar cells.

Using a concentrating device, the sunlight is concentrated on the black body heat absorbing material on the back of the cathode, and the cathode is heated to 1000°C. Due to the good thermal conductivity of diamond, the temperature of the tip of the small cone will also be close to 1000°C, and the energy gap of diamond will be Electrons also transition from the valence band to the conduction band due to thermal oscillations due to the reduction in heat. Under the action of an applied electric field, a flow of electrons from the cathode to the anode is generated.

Claims (3)

1, a kind of diamond thin-film solar cell, it is characterized in that: on metallic cathode, a large amount of pyramid diamond boccas distribute, by the beam condensing unit heated cathode, make negative electrode reach temperature more than 1000 ℃, a large amount of electronics are emitted from the tip of bocca, and under the effect of extra electric field, electron stream forms electric current to metal anode.

2, the manufacture method of diamond thin-film solar cell according to claim 1 is characterized in that realizing by following steps:

(1) utilize chemical etching method or laser direct writing method, go out aperture equally distributed in a large number, that diameter is about 5 μ m in the Surface Machining of silicon base, hole depth is 4～5 μ m, and aperture is square arrangement on the silicon base surface, and pitch of holes is about 10 μ m, every cm ²Little hole number on the area is in ten million magnitude;

(2) utilize microwave plasma CVD method (MPECVD), growing diamond membrane on silicon base, working gas are hydrogen (H ₂), methane (CH ₄) and oxygen (O ₂); Deposition parameter is: 1000 ℃ of substrate temperatures, microwave power 3.5kW, the air pressure 5kPa of settling chamber, hydrogen flowing quantity 200sccm, methane flow 8sccm, oxygen flow 1sccm.Will grow pyramidal diamond bocca in the aperture, the control growing time, can change the yardstick of bocca, make cone base size Control at 3 ~ 4 mu m ranges;

(3) there is the silicon base back side of pyramid diamond bocca to add metal level in growth, adds the combination of one deck black matrix heat-absorbing material and metal anode on the metal level again, add electric field at two interpolars during work, constitute diamond thin-film solar cell as negative electrode.

3, the operation principle of diamond thin-film solar cell according to claim 1, it is characterized in that realizing: utilize beam condensing unit by following steps, sunlight is gathered on the black matrix heat-absorbing material of cathode back, negative electrode is heated to 1000 ℃, because adamantine thermal conductive resin, the tip temperature of bocca also will be near 1000 ℃, and adamantine energy gap can be because of the reduction of being heated, and electronics also can transit to conduction band from valence band because of thermal oscillation; Under the effect of extra electric field, can produce the electron stream from the negative electrode to the anode.

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