| At this stage,human society is facing an energy crisis caused by the over-exploitation of traditional fossil fuel industry.Renewable energy,especially solar energy,has become one of the research hot spots.With the acceleration of the research and exploration of solar energy technology around the world,scholars turn to focus on how to manufacture solar cells with high conversion efficiency and low cost.Ga As-based solar cells,characterized by high photoelectric conversion efficiency,high temperature resistance,corrosion resistance,strong stability,high radiation resistance,well spectral matching performance,large light absorption coefficient,are widely used in the field of space energy.However,the key to further improve the photoelectric conversion efficiency of Ga As-based series solar cells is to reduce the reflection loss on the cell surface and increase the absorption of sunlight.In this thesis,based on the theory of optical thin films,The Essential Macleod（TFC）software is used to simulate and design double-layer and multilayer antireflection coatings on triple-junction inverse In Ga P/Ga As/Ga In As solar cell at a wide spectral range（300～1400 nm）.Plasma enhanced chemical vapor deposition and Radio frequency magnetron sputtering processes are used to complete the experiment on the Ga As substrate,meanwhile,the relationships between thermal annealing（400～700℃）and morphology,structure,optical properties and surface wettability of the coatings are also investigated.The Essential Macleod software is used to simulate and design antireflection coatings matching Ga As solar cells,and Simplex optimization algorithm to change the physical thickness of the films in a wide spectral range（300～1400 nm）.The simulation mentioned above mainly obtained Si O2/Si3N4、Si O2/Hf O2、Si O2/Zn O、Si O2/Ti O2、Ti O2/Si3N4/Si O2、Si O2/Si3N4/Si O2/Si3N4、Ti O2/Si3N4/Si O2/Si3N4/Si O2、Si O2/Si3N4/Si O2/Si3N4/Si O2/Si3N4thin films system,theoretical minimum average reflectance values of the designs were 3.71%,4.42%,8.04%,9.53%,4.76%,7.45%,2.4%,8.47%,respectively.Through the analysis of the reflectance 3D map obtained by simulating the sunlight at different incident angles,it can be inferred that the double-layer and multilayer antireflection coatings could meet the performance requirements of the antireflection coatings for solar cells,which cover the incident angle at a range of 0～60°.The above-mentioned bilayer/multilayer antireflection coatings prepared by Plasma enhanced chemical vapor deposition and Radio frequency magnetron sputtering processes showed excellent antireflection performance in a wide spectral range.Among them,the average reflectance of deposited Si O2/Si3N4 thin film is 14.19%,and optimal antireflection performance is reached after annealing at 700℃,is 12.65%;the average reflectance of deposited Si O2/Hf O2 thin film is 14.57%,and optimal antireflection performance is reached after annealing at 700℃,is 12.28%;the average reflectance of deposited Si O2/Zn O thin film is 14.6%,and optimal antireflection performance is reached after annealing at 600℃,is 7.05%;the average reflectance of deposited Si O2/Ti O2 thin film is 14.55%,and optimal antireflection performance is reached after annealing at 600℃,is 12.33%;the average reflectance of deposited Ti O2/Si3N4/Si O2 thin film is 12.13%,and optimal antireflection performance is reached after annealing at 700℃,is 7.84%;the average reflectance of deposited Si O2/Si3N4/Si O2/Si3N4 thin film is 17%,and optimal antireflection performance is reached after annealing at 600℃,is 14.42%;the average reflectance of deposited Ti O2/Si3N4/Si O2/Si3N4/Si O2 thin film is 14.19%,and optimal antireflection performance is reached after annealing at 600℃,is 6.71%;the average reflectance of deposited Si O2/Si3N4/Si O2/Si3N4/Si O2/Si3N4 thin film is 15.55%,and optimal antireflection performance is reached after annealing at 600℃,is 14.47%.The influence of annealing temperatures on the structure,morphology,optical properties and surface wettability of the thin films shows that physical thickness of the double-layer antireflection films decreases with the increase of the annealing temperature,and show a positive correlation with surface roughness.Besides,TEM bright-field image demonstrates the cross-sectional morphology and element distribution of the multilayer antireflection films,and it is proved that the multilayer antireflection films is amorphous after deposited combined with the results of XRD and SAED;GMS 3 software is used to analyze the results of the layer thickness of the antireflection films,which shows that the relative error between experimental and simulation results of the total physical thickness of the film is less than 5%;the reflectivity and roughness of the film show a positive correlation trend,the better optical performance is found with lower surface roughness of the film.From the experimental conclusion,both double-layer and multilayer antireflection films are hydrophilic films,and the surface wettability of the double-layer films are negative correlation with the film roughness,which is in accordance with the theory of Wenzel,the higher the surface roughness,the stronger the hydrophilicity.However,the surface wettability of the multilayer（n≥3）antireflection films shows a positive correlation with the film roughness,which is inferred to be related to the crystallization of the film,surface energy and porosity.Comparing simulation and experimental results,it can be seen that large gap can be found between the measured and simulated reflectance curve of the film prepared by Magnetron sputtering at the range of ultraviolet and visible wavelength.Meanwhile,little difference can be found between measured and simulated reflectance curve of the film prepared by Chemical vapor deposition,however,and several of the measured data are still higher than the simulated values.It is inferred that the possible reasons are:（1）Deposition rate is difficult to control due to The long process of Magnetron sputtering deposition,and the accumulation of film thickness errors is easy to produce,as long as the inaccurate refractive index is caused;（2）The uniformity of the film,thermal stress,and surface microstructure changes lead to the changes in the refractive index and cause errors during the deposition process;（3）The more layers of the films prepared by Chemical vapor deposition,the higher impurity content is produced in the films,which causes the higher reflectance value than the simulated one. |
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