Future directions for higher-efficiency HIT solar cells using a Thin Silicon Wafer

To reduce the power generation cost of heterojunction with intrinsic thin layer (HIT) solar cells, it is necessary to use a thinner crystalline silicon wafer, as well as to improve the conversion efficiency. We have experimentally confirmed that VOC of the HIT solar cell increases with decreasing the wafer thickness, and can reach a very high VOC of 747 mV with a 58-μm-thick wafer owing to a sufficiently low surface recombination velocity. We also indicate the future directions for improving the efficiency. The uniformization of the texture size of the silicon surface and reduction of the carrier density in TCO film while maintaining an equal or lower conductivity are effective for improving the optical confinement.

► The VOC of the HIT solar cell increases with decreases in the wafer thickness.
► The surface recombination velocity of the HIT solar cell is a sufficiently low value of 4 cm/s.
► We have achieved the very high VOC value of 747 mV with a 58-μm-thick c-Si wafer.