Record Setting Amorphous Silicon Alloy Triple-Junction Solar Cell with 14.6% Initial and 12.8% Stable Efficiencies

World record 14.6% initial and 12.8% stable conversion efficiencies have been achieved using amorphous silicon based alloy in a spectrum-splitting, triple-junction structure. This performance exceeds our previous record of 13.2% initial and 11.8% stable efficiencies and establishes a new milestone toward reaching the 15% stable module goal. Key factors leading to this major advance include: (a)Improvement in the low bandgap amorphous silicon-germanium component cell that resulted in enhanced red response and provided desired current mismatching, (b) improvement in the pn tunnel junction between component cells by incorporating microcrystalline p and n layers in a multilayered structure that resulted in reduced optical and electrical losses, and (c) improvement in the top conductingoxide that resulted in reduced absorption and enhanced blue response without increasing the top cell thickness. Details of these advances along with light-soaking data for high efficiency cells will be discussed.