The optical and photoelectrical characteristics of amorphous As ₂Se₃:Sn and Sb₂Se₃:Sn prepared by vacuum evaporation on glass substrates are investigated. From the transmission spectra the changes of the refractive index under the light irradiation and heat treatment are calculated. The band gap for amorphous Sb₂Se ₃ was found to be E_g=1.30 eV and decrease with increasing of the tin concentration up to E_g=1.0 eV for Sb₂Se ₃:Sn_10.0. The kinetics of photoinduced absorption in the investigated thin films was studied. The relaxation of the photocurrent has been recorded in the wide times scale (from 0.05 up to 25 s) and was determined by capture on the deep acceptor-like traps. The photoconductivity spectra of amorphous Sb₂Se₃ and Sb₂Se₃:Sn films in the photon energy range 1.0/2.5 eV show the band connected with the presence of the defect states with the maximum located at 1.46 eV. The intensity of this band increases in the samples with tin impurity. The experimental data are discussed in framework of the model of the charged defects and non-equilibrium dielectric polarization in amorphous semiconductors