A multi-stack Al 2 O 3 /HfO 2 design with contact openings for front surface of Cu(In,Ga)Se 2 solar cells

A new multi-stack approach with contact openings was investigated for front surface of Cu(In,Ga)Se 2 thin film solar cells. In this multi-stack design, a thin HfO x layer was used to protect a thicker AlO x layer from the presence of ammonia in the chemical bath deposition. The contact openings were created by using alkali solution. The lifetime decay was improved by implementing multi-stack passivation layer between CIGS/buffer layer interface. It was shown that open circuit voltage was increased by up to 30mV.