Oxygenation and air-annealing effects on the electronic properties of Cu(In,Ga)Se2 films and devices

A study on Cu(In,Ga)Se2-based polycrystalline thin film solar cells presents a comprehensive picture of chemical oxygenation effects and their consequences for the electronic properties of such Cu(In,Ga)Se2-based solar cells. Two distinct effects of air annealing of the absorber surface were observed: first, oxygenation leads to passivation of surface defects both at the grain boundaries and at the free surface of the Cu(In,Ga)Se2 film. Second, air annealing at 200 degrees C leads to a decrease in CU concentration at the absorber surface, which ultimately results in a decrease of space charge density within the absorber.