Abstract
Surface passivation is the essential process for enhancing the performance of silicon solar cells. Among all the passivation materials, aluminum oxide (Al2O3) has proved to be a high quality passivationmaterial due to its high density of negative fixed charges. In this study, we form the Al2O3 film by anodization and apply this passivation layer onto the rear side of PERC solar cell. Moreover, the aluminum back contact are formed by making aluminum electrode penetrate the Al2O3 layer at high temperature instead of the conventional laser ablation process. By finding the optimum anodization time period, thermal annealing temperature and annealing time, Al2O3 layer shows a perfect field-effect passivation on the silicon surface. In order to investigate the material characteristics of Al2O3 before and after annealing, the negative charge density is analyzed by C-V measurement. Then, the elemental composition and the film thickness are measured by XPS and TEM, respectively. Finally, we integrate the Al2O3 rear passivation effect with a patterned aluminum paste back contact in fabricating a PERC multi-crystalline silicon solar cell. The PERC solar cell shows a fill facor of 73.1% and a conversion efficiency of 16.13%, which gives an efficiency improvement of 0.21% absolute in comparison with the reference cell.