15.9% efficiency solar cells on electromagnetic cold crucible cast multicrystalline silicon

Abstract

Hydrogen passivation is found very effective in improving the quality of electromagnetically cased (EMC) multicrystalline silicon from Osaka Titanium Co. (OTC), now Sumitomo Sitix Corp.), due to its small grain size and low oxygen content. A top efficiency of 15.9% is achieved for a 4 cm2 solar cell fabricated on hydrogen passivated EMC-OTC multicrystalline silicon. Such a result is comparable to the top efficiencies achieved on high quality conventionally casted material and represents the maximum efficiency ever reported for EMC multicrystalline silicon. Fourier transform infrared measurements confirm the low oxygen content in the EMC-OTC material and spectral response as well as contactless lifetime measurements confirm the role of the plasma hydrogen passivation in substantially improving the diffusion length in this material.