A Research On The Antireflection Layer Technology Of New Anti-PID Monocrystalline Silicon Solar Cells

In this work,nitrous oxide(N2O)is introduced into the coating process of conventional solar cell production,and four layers of thin film are deposited on the surface of a monocrystalline silicon cell as antireflection film through plasma enhanced chemical vapor deposition(PECVD),to produce the monocrystalline silicon solar cells with the adverse effect of Potential Induced Degradation(PID).The influence of different process parameters on the film was studied,and the formed films and cells were tested and analyzed.The PC1D software was used to simulate antireflection layer of the battery,and several combinations of film thickness and refractive index were selected according to the obtained electrical parameters of the simulation.According to the simulation results,four layers of thin films were deposited by PECVD equipment under the new process of nitrous oxide.After several experimental analysis and continuous adjustment process,the optimized process parameters of the antireflective layer were determined.First,a layer of silicon oxide that is thin enough and compact enough is deposited on the surface of the monocrystalline silicon wafer,to keep the Na+ of the glass from entering in the surface of the cell and take effect of the surface passivation.Later the deposition of silicon nitride and silicon oxynitride layer,as the refractive index buffer layer,reduces the high extinction coefficient caused by the high refractive index between the films,and reduces the reflection between the films.Finally,the silicon oxide layer of lower refractive index makes the whole film meet the design requirements,and it matches with the battery packaging material EVA.The thickness and refractive index of the film were measured by an ellipsometer,the thickness of the first layer of silicon oxide film was 10nm,and the refractive index was 2.4;the thickness of the second layer of silicon nitride was 40nm,the refractive index was 2.32;the thickness of the third layer of silicon oxynitride was 25nm,the refractive index was 1.98;the fourth layer of silicon oxide film thickness 36nm,the refractive index of 1.57.Ultimately,the battery surface was dark blue,and film is uniform and has no color difference.Due to some factors,for instance,existence of inter membrane diffusion,the total thickness of the antireflective layer is 74.9nm and the refractive index is 2.16.Reflectivity tests show that the average reflectivity of the coating cells is 5%,and it reduces to a minimum of about 0.3%at the incident light wavelength of 570nm,significantly reducing the reflection of light on the surface of the cell and increasing the utilization of light.EDS test gives that:in the battery Si:N:O = 5.35:1.52:1,silicon content in sample is high.The cell of monocrystalline silicon(156.75mm × 156.75mm)has better parameters,average short circuit current of 9.428A,and average photoelectric conversion efficiency of 19.81%.