24.7% Record Efficiency HIT Solar Cell on Thin Silicon Wafer

A new record conversion efficiency of 24.7% was attained at the research level by using a heterojunction with intrinsic thin-layer structure of practical size (101.8 cm(2), total area) at a 98-mu m thickness. This is a world height record for any crystalline silicon-based solar cell of practical size (100 cm(2) and above). Since we announced our former record of 23.7%, we have continued to reduce recombination losses at the hetero interface between a-Si and c-Si along with cutting down resistive losses by improving the silver paste with lower resistivity and optimization of the thicknesses in a-Si layers. Using a new technology that enables the formation of a-Si layer of even higher quality on the c-Si substrate, while limiting damage to the surface of the substrate, the V-oc has been improved from 0.745 to 0.750 V. We also succeeded in improving the fill factor from 0.809 to 0.832.