Interface oxygen and heat sensitivity of Cu(In,Ga)Se2 and CuGaSe2 solar cells.

Combined oxygen and heat exposure processes after p-CuGaSe₂/n-CdS junction formation degrade CuGaSe₂ solar cell efficiency, whereas such annealing processes can improve high In content Cu(In,Ga)Se₂ device performance. This result is chiefly attributable to different interface structures consisting of oxygen-sensitive CuGaSe₂ or relatively oxygen-insensitive Cu(In,Ga)Se₂. To reduce CuGaSe₂ interfacial recombination, reduction of the process temperature of the front contact layer deposition process is found to be the key. In this work, fill factor values exceeding 0.7 are reproducibly obtained from CuGaSe₂ solar cells, though such high fill factor values have been very challenging to demonstrate to date using CuGaSe₂ photoabsorber layers. [ABSTRACT FROM AUTHOR]