Chinese firm's new back-contact solar cells offer 27% efficiency

Chinese manufacturer Longi, in collaboration with Sun Yat-sen University researchers, has developed a new approach to enhance the efficiency of high-resistivity, lightly doped silicon wafers for solar cells. These wafers theoretically offer higher efficiency due to fewer recombination sites, but their fragility has limited commercial adoption. The team addressed this challenge by applying in-situ edge passivation to control edge recombination, which is a major factor reducing performance in these wafers. This passivation preserves carrier collection and enables the wafers to realize their intrinsic potential for high fill factors and efficiency. The researchers fabricated hybrid interdigitated back-contact (HIBC) solar cells using both high-resistivity (8–10 Ω·cm) and standard Czochralski-grown wafers (1.0–1.5 Ω·cm) to directly compare performance. Their results showed that edge passivation significantly improved efficiency, especially in high-resistivity wafers, which are more sensitive to edge