Yasushi Yoshino

Effect of glass frit in metallization paste on the electrical losses in bifacial N-type crystalline silicon solar cells

N-type crystalline silicon can be expected to achieve high-efficiency compared with p-type one. For the n-type solar cells, silver/aluminum paste has been used as metallization for p+ emitter, which induces loss in open circuit voltage (Voc) of the cells. In this study, the effects of glass frit in the metallization paste on the loss in Voc are investigated, dividing the respective effects of the glass frit and the aluminum in the paste. The glass frit in the metallization paste decreases the Voc due to shunting of p-n junction and increasing recombination current, even if the paste contains no aluminum.

SiO2/SiNx stacking layer for rear surface passivation of PERC

We investigated to apply thermal SiO2/APCVD SiO2/PECVD SiNx stacking layer to the rear surface passivation of PERC. After rough optimization of process conditions of LCO and firing steps, the cell efficiency reached 19.3% and it was 1.1% absolute higher than that of the conventional cell. The results of CV measurements suggest that the hydrogen released from the PECVD SiNx during the firing reduces Dit and the deposition of SiO2 by APCVD is effective to reduce Qf. By combining these two effects, both Dit and Qf of the thermal SiO2/APCVD SiO2/PECVD SiNx stacking layer are largely reduced. Therefore, the thermal SiO2/APCVD SiO2/PECVD SiNx stacking layer is suitable for rear surface passivation of PERC.