| In NIP silicon thin-film solar cells, Al/ZnO back reflector can greatly improve the solar cell performance. Solar cell can copy the morphology of back reflector and form a better trapping light structure, as a result, the light path in the cell increase and the effective absorption of solar cell enhance, so that conversion efficiency is improved.In this paper, Al/ZnO back reflector is prepared by magnetron sputtering. It is studied the influence of sputtering process conditions on properties of Al films and found that the Al film is more rough and light scattered increased when substrate temperature is higher, sputtering power and pressure are appropriate,and the thickness of Al film is over 780nm, but at the same time, the integrating sphere reflection of thin films could be reduced. It is also found that the impurities introduced during film deposition will inhibit the grain growth and lead to RMS decrease. The impurities are more easily introduced when substrate temperature is high. Using double-layer Al film structure, RMS value is reduced not so much, but the reflection index increased from 65% to 82% at 650nm.Al film determines the reflectivity of Al/ZnO back reflector. When the thickness of ZnO increases, the interference of Al/ZnO film become more severe. After calculation, the ideal thickness of ZnO used in this paper in Al/ZnO back reflector should be about 100nm.Al/ZnO back reflector was optimized and used in NIP amorphous silicon solar cell, and it is found that the larger roughness of Al/ZnO back reflector, the effect of trapping light is better. It is got the highest conversion efficiency of 5.6%. |
PDF Full Text Request