The invention concerns a method for making thin-film CIGS which consists in: electrochemically depositing on a substrate a layer of stoichiometry close to CuInSe₂; then rapidly annealing said layer from a light source with pulses of sufficient power to recrystallize CIS. Advantageously, the electrodeposited elements are premixed. Thus, after the deposition step, a homogeneous matrix is obtained which can support sudden temperature increases during the rapid annealing.