Abstract Polycrystalline films of n-Cd 1 − x Zn x S 1 − y Se y with different x and y values (0.1 ≤ x ≤ 0.8 and 0 ≤ y ≤ 0.2) were prepared by electrodeposition from solution of CdCl 2 + ZnCl 2 + Na 2S 2O 3 + SeO 2 (or Na 2Se 2O 3) on p-Si substrates. The dependence of the electric and photoelectric parameters in these heterojunctions on the x, y and heat treatment condition were investigated. It was found that annealing the heterojunctions at T a = 400 °C for τ a = 5 ÷ 6 min in air leads to an improving of the electric and photoelectric parameters. The evaluation of solar cell parameters was carried out using the dark and light current–voltage characteristics. Under AM 1.5 condition the open circuit photovoltage and short circuit photocurrent density of cells p-Si/n-Cd 03Zn 0.7S 0.8Se 02 were V oc = 0.6 V, J sc = 22.8 mA/cm 2, respectively.