Photodarkening relaxation under light exposure of a-As₂Se₃ amorphous films doped with 0.5 at.% tin, manganese, samarium and dysposium, separately introduced, was studied in dependence on the impurity type and thermal annealing. Both factors reduce photodarkening and the degree of reduction depends on the type of impurity. The relaxation process may be described by a stretched exponential with the dispersive parameter 0.5<α[removed]