[19p-B12-1~10] The present and future of crystalline Si solar cells

[19p-B12-9] Development of Rib-Si Solar Cells

〇Makoto Konagai¹ (1.Tokyo City Univ.)

Keywords:solar cell, Rib-Si solar cell, heterojunction solar cell

In order to improve the conversion efficiency of Si solar cell, we are developing Si solar cells with very thin wafer of 80 micrometer or less. It is known that thinning the Si wafer makes it impossible to maintain the mechanical strength, and in production the yield is greatly reduced due to the cracking of the wafer. Therefore, in order to reduce the thickness of the wafer while maintaining the mechanical strength, our group has developed a solar cell with a Rib structure. In the Rib structure, the Rib region of about 10% in area ratio mechanically supports the thinned region. There are thick regions (as thick as the original wafer) and thin regions (etched regions) in the Si wafer. So far, we have developed the basic processes for fabricating the Rib structure and reported the initial characteristics of the Rib solar cell. In this work, we developed a process to texture both sides of Rib wafer aiming at improving short-circuit current density, and fabricated a heterojunction solar cell using a stacked-buffer layer using i-a-SiO:H / i-a-Si:H. As a result, conversion efficiencies of 19.4% and 18.4% have been achieved for the thickness of 80 and 40 micrometer, respectively.