High-efficiency solar cells on edge-defined film-fed grown (18.2%) and string ribbon (17.8%) silicon by rapid thermal processing

摘要

Solar cell efficiencies of 18.2 and 17.8% were achieved on edge-defined film-fed grown and string ribbon multicrystalline silicon, respectively. Improved understanding and hydrogenation of defects in ribbon materials contributed to the significant increase in bulk lifetime from 1-5 μs to as high as 90-100 μs during cell processing. It was found that SiN_(x)-induced defect hydrogenation in these ribbon materials takes place within one second at 740-750℃. The bulk lifetime decreases at annealing temperatures above 750℃ or annealing times above one second due to the enhanced dissociation of the hydrogenated defects coupled with the decrease in hydrogen supply from the SiN_(x) film deposited by plasma enhanced chemical vapor deposition.