Study On Light Induced Degradation Effect Of P-type Mc-Si PERC Solar Cells

In recent years,multicrystalline silicon?mc-Si?PERC?passivated emitter and rear cell?solar cells have been developed rapidly due to their good compatibility with conventional solar cell production lines,low cost and obvious improvement of efficiency.With the optimization and upgrading of production technology,the gap of conversion efficiency between industrial mc-Si PERC solar cells and lab-made mc-Si PERC solar cells has been reducing,However,improving efficiency is getting harder.On the other hand,the problem of light induced degradation?LID?effect in mc-Si PERC solar cells has not been well solved.The attenuation rate of mc-Si PERC solar cells is even more than 5%and the attenuation rate increases with the increase of irradiation intensity and temperature.The LID effect of mc-Si PERC solar cells will lead to the reduction of power generation,which will bring huge losses to owners of photovoltaic power generation and is not conducive to the development of photovoltaic industry.In this thesis,the effects of back passivation technology and different sintering and injection annealing conditions on the LID effect of mc-Si PERC solar cells were systematically studied,which will provide a reference for the production process and LID suppression of mc-Si PERC solar cells.In this thesis,Al₂O₃/SiN_x laminated passivation films with different conditions were prepared by PECVD by changing the relevant process parameters of deposition of passivation films.The influences of Al₂O₃ film thickness,SiN_x film thickness and SiN_x refractive index on the passivation performance of crystalline silicon surface were studied systematically.The optimum process conditions of Al₂O₃/SiN_x laminated passivation film were obtained.The results showed that when the thickness of Al₂O₃ film was 10.8 nm with the thickness of SiN_x film of 120 nm and the refractive index of SiN_x of 2.2,both the back passivation effect and the performance of mc-Si PERC solar cells were the best.At the same time,degradation treatment was carried out on mc-Si PERC solar cells with different passivation film conditions,and the results showed that changing the passivation film conditions did not affect the LID effect of mc-Si PERC cells.Secondly,the sintering conditions of mc-Si PERC solar cells were changed by adjusting the technological parameters of chain sintering furnace.The influences of sintering belt speed,sintering peak temperature and sintering curve on the LID effect of mc-Si PERC solar cells were studied.The results showed that the peak sintering temperature and sintering curve had a great influence on the LID effect of mc-Si PERC solar cells except sintering belt speed.Under certain conditions,the attenuation amplitude increases with the increase of the peak sintering temperature and decreases with the advance of the peak temperature position in the sintering curve.The attenuation rate of the conversion efficiency of mc-Si PERC solar cells prepared by the optimized sintering curve was only2.30%after 45 h of light illumination,which provided a new idea for the study of LID suppression of mc-Si PERC solar cells.Finally,by changing the process parameters of irradiation annealing furnace,the process of suppressing the LID effect of mc-Si PERC solar cells by irradiation injection annealing was optimized.The effects of irradiation annealing time,irradiation annealing temperature and irradiation intensity on the LID effect of mc-Si PERC solar cells were studied.The optimum irradiation injection annealing conditions were obtained.In addition,electrical injection annealing treatment on mc-Si PERC solar cells was also carried out.By comparing with the group without any treatment,it was found that mc-Si PERC solar cells with the electric injection annealing treatment also had better LID suppression performance.