Electronic properties of solution-processed Cu(In,Ga)(S,Se)2 solar cells using metal chalcogenides and amine-thiol solvent mixtures

This work examines the effects of post-deposition air-annealing on the electronic properties of solution-processed heterojunction CIGS solar cells. The annealing in air of the CIGS/CdS interface was found to have positive effects on the device performance with an increase in all PV parameters even after annealing times as short as 5 min. A VOC increase of <; 130 mV was caused by the reduced surface and grain boundary recombination through passivation of surface Se deficiencies with oxygen atoms. Prolonged annealing causes charge redistribution and diffusion of mobile elements such as Cu and Cd deeper into the absorber bulk however, resulting in lower carrier density and deeper defects with increased annealing time. These were observed through capacitance-voltage profiling and admittance spectroscopy.