Stable amorphous silicon double stacked solar cell using low band gap amorphous silicon bottom i layer

We studied the preparation of low‐band‐gap amorphous silicon(a‐Si) and the photovoltaic applications of this material. We obtained a‐Si with optical band gap between 1.60 and 1.65 eV with hydrogen content less than 6 at.% and used this material as the bottom i layer of a‐Si double‐stacked solar cells. The conversion efficiency is about 9% and the degradation is less than 4% after light exposure for 100 h under 350 mW/cm2.