Crystalline Silicon Solar Cell Surface Passivation, Pn Junction, Measured By The Aluminum Back Surface Field And The Minority Carrier Lifetime

This paper includes three parts. In the first one, a theoretical passivating model has been developed for fabricating silicon solar cells. On the base of these theory calculations, we passivated the front-surface both of different surface doping concentration solar cells by a thin layer of thermally grown SiO2. The results show that the in heavy surface doping concentration cell is lower compared to the cell in light surface doping concentration. The majority of improvement in comes from the emitter surface passivation.In the second one, we firstly compared two kinds of solar cells in industry and analyzed their junction depth and doping concentration. Then we studied the effect of junction uniformity on the aluminum-alloyed back surface field to solar cell performance. The formation theory of aluminum-alloyed back surface field, the effect parameters to the doping concentration and the junction depth were analyzed. In experiment both different aluminum were screen printed on the silicon and then sintered in the same conditions, the results show the open voltage and the IQE of long-wave with the uniformity junction solar cell is higher than the junction non-uniformity one,which provided a good technical guiding for the industry.In the third one we investigated the measure of minority carrier lifetime in silicon solar cells by the photo-induced open-circuit voltage decay (OCVD). In according to the principal of solar cell, the excess minority carriers are generated and open-circuit voltage is created because of the external pulsed optical excitation. We define the recombination time of excess electrons in P field as the minority carrier lifetime. In theory, we developed the equation between excess minority carriers lifetime and the open-circuit voltage decay; moreover, the effect of capacitance to general open-circuit voltage is also investigated. Both different efficiency solar cells are measured by the method and showed the relations between the minority carrier lifetime and the performance of solar cells, which provides great useful guidelines for fabricating high-efficiency silicon solar cell in industry.