Co-diffused back-contact back-junction silicon solar cells

Abstract

The driving force in photovoltaics is the reduction of the ratio between device costs and conversion efficiency. The present research study introduces a highly innovative diffusion process, called co-diffusion, which allows for a drastic decrease in process costs, on the one hand, and the assembly of a highly efficient solar cell device, the back-contact back-junction (BC-BJ) silicon solar cell, on the other. The co-diffusion approach is based on pre-patterned layers, which contain dopants, deposited by means of plasma enhanced chemical vapor deposition and diffusion in a tube furnace, which contains dopant gases in the process atmosphere. The solar cells are built on n-type silicon which features a high potential in achieving a high silicon life time, which is a necessary requirement of highly efficient BC-BJ solar cells. Fundamental knowledge in terms of co-diffusion processes can be gained from this research study. The processes allow for the fabrication of BC-BJ solar cell devices with a conversion efficiency exceeding 21 percent.