Optimization of thermal processing and device design for high-efficiency c-Si solar cells

To improve the cell performance of single-crystal silicon solar cells, the process conditions have been optimized by monitoring the bulk lifetime after each thermal step in the cell fabrication process. The emitter geometry, i.e., front and rear contact size and pitch were optimized, and the cells were fabricated through a set of environmentally considered processes, especially for surface treatment, oxidation, diffusion, and electrode fabrication. Conversion efficiency of 22.3% in a 4 cm² cell, and 22.6% in a 1 cm² cell, was attained, respectively, with structural features of SiO₂ single-AR, “inverted-pyramid” fron texture, point-contact with line-emitter for front electrodes, and locally diffused BSF for rear contacts.