Abstract 1. Introduction Solar cells are subject to the wear and tear of dust and sand in the external environment due to the lack of battery protection film, thus affecting the transmission efficiency of the battery. At present, the addresses of photovoltaic parks in the world are usually located in desert areas, and frequent sandstorms will cause solar cell protective film...
1. Introduction Solar cells are subject to wear and tear of dust and sand in the external environment due to the lack of a battery protective film, thereby affecting the transmission efficiency of the battery. At present, the addresses of photovoltaic parks in the world are usually located in desert areas, and frequent sandstorms will cause abrasion and erosion of solar cell protective films. Carbon atoms can hybridize in a variety of ways to form structures in three spatial coordinates in the form of covalent bonds. The diamond film has high mechanical hardness, infrared transparency and superior chemical inertness due to the sp3 component in the amorphous matrix of the internal structure; high optical transparency and good neutralization and high hardness make the diamond film suitable for the diamond film. The protective layer of photovoltaic solar cells.
1.1 Diamond film amorphous carbon on the surface of photovoltaic solar cells , such as diamond-like carbon, high hardness, good chemical stability and radiation stability, optical properties are easy to modify, so it is suitable for the protective layer of silicon solar cells. In addition, nano-diamond films are used in insulating devices and semiconductor devices of photovoltaic cells, and can also be used for protective layers.
In this study, a diamond substrate deposited on a glass substrate was prepared as a protective film for photovoltaic solar cells and a higher film transparency was obtained to improve the transmission efficiency of the solar cell.
1.2 Diamond film protective layer The diamond film protective layer of solar cells can be prepared by controlling the refractive index and transmittance of the diamond film. The particle size and roughness of the diamond film as well as the quality of the film affect the projection rate. The single crystal diamond has a small particle size and a smooth surface, so the experiment uses single crystal diamond as an experimental material.
Adhesion between diamond and glass substrate is one of the key issues in the experiment due to tensile stress and delamination between layers of different materials. Figure 1 is a comparison of the scratch resistance of an ultra-thin diamond-like carbon coating on a glass substrate.
1.3 HFCVD deposition method The diamond film was prepared by hot wire chemical vapor deposition (HFCVD). The experiment was simple and the cost was low. A gas mixture is introduced from the top of the vessel and passed through a tungsten wire placed on the sample to react to deposit carbon atoms on the substrate as shown in the following figure.
2. Experimental procedure 0215 glass slides (10 x 10 mm) with a thickness of 0.96-1.06 mm were cut from the frosted glass slides. The sample was subjected to ultrasonic cleaning with acetone for 5 minutes. The sample was then placed in ND-DMSO-X solution for seeding, the purity of the solution was >98%, the cubic phase, the particle size was 4-5 nm, and the average size of the agglomerate block was 30 nm. The mixing ratio of ND-DMSO-X solution to methanol was 1:3. The beaker containing the sample and the solution was placed in the ultrasonic wave for 90 minutes, and then the sample was ultrasonically washed with methanol for 5 minutes. Two tungsten wires (ø = 0, 25 mm) were discharged into the HFCVD reactor.
Table 1 is the relevant parameters of the experimental deposition method:
3. Results and discussion
3.1 SEM analysis After depositing the sample, the diamond crystal was analyzed by an optical microscope, and crystals of different sizes on the surface of the sample were observed. The particle size, surface morphology and film thickness were then investigated by scanning electron microscopy and obtaining a magnified image.
In Figure 3, it can be seen that the glass sample has been covered with a diamond film, the film has a small particle size, a good crystal cluster, and a smooth surface; therefore, the transmittance is also high.
3.2 Spectrophotometric analysis When a beam of different wavelengths of light is irradiated onto an object, the spectrophotometric method can analyze the light absorption characteristics of the substance. Therefore, a spectrophotometer is used in this experiment. Transmittance is the ratio of the density of light before it penetrates an object to the density of the remaining light after it penetrates the object. Transparency is based on this concept and refers to the density of light that an object can allow to penetrate.
Figure 5 shows the transparency comparison of the glass samples before and after film deposition. It can be seen that the film thickness is only 500 nm, but it has a great influence on the transmittance. This is due to the light scattering of the light as it penetrates the sample; this indicates that the film has a large roughness and a large particle size.
4. Conclusions The diamond film was successfully prepared by HFCVD method with small particle size, high transparency, good coverage of glass substrate and high transmittance. The next step will focus on the morphology of the film, the adhesion characteristics between the glass and the film. (Compile: China Superhard Materials Network)
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