Pulse Selenization in Cu(In,Ga)Se₂ Solar Cells: A Promising Approach to Achieve High Efficiency by Electrodeposition

Nowadays, one-step selenization is widely used in the post-selenization of electrodeposited Cu(In,Ga)Se2 (CIGS) films. However, it often causes the accumulation of gallium (Ga), forms fine grains near the molybdenum (Mo) layer, and deteriorates the device performance of solar cells. Herein, through a pulse halogen lamp, pulse selenization is employed to reinforce the temperature of the sample surface, which is beneficial for the formation of CIGS on the surface. We find that pulse selenization provides a feasible approach to inhibit Ga diffusion toward the CIGS back and improve the Ga content on the CIGSe surface. Further investigations on the changed defect distribution indicate that pulse selenization can turn InCu2+ defects into neutral NaCu defects, promote the disintegration of the neutral (2VCu– + InCu2+) defect pair, leading to the enhanced number of VCu– in CIGS films, and thus result in an impressive efficiency of 12.35% (a relative increase of about 38% compared with that of the reference sample). This work aims at providing a practical and operable route for the post-selenization of electrodeposited CIGS films.