The research on binary chalcogenides as photovoltaic materials offers a great opportunity to lower the manufacturing costs of solar cell devices. Thus, we choose to research tin sulfide (SnS) materials as a p-type layer in the SnS/Si heterojunction. Our research reports basic characterizations related to the annealing effect on the SnS films. The effect of substrate type was considered, where SnS films were deposited on glass and Si substrates. The Orthorhombic SnS phase is the main crystal structure of the as prepared polycrystalline SnS films. After thermal treatment, the deposited films on glass substrates maintained the same preferred orientation while deposition on Si changed the preferred orientation to the Sn₂S₃ phase. The intensity of observed reflections in XRD charts decreased with increasing temperature of annealing (T_a) and the treated SnS film at T_a = 673 K showed an absence of ordered structure. The indirect transition showed the best linear fit for all investigated SnS films. The reported band gap energy (E_g) values increased after annealing from 1.29 to 1.50 eV. The thermal induced electrical behavior for SnS films showed the presence of deep impurity levels. Further, we conclude from the calculated values of σ_oΙ that localized states-driven conduction is more reasonable in the high-temperature region. Besides, the SnS films exhibited dc conductivity in the range of 3 × 10^-3–6 × 10^-6 (Ω.cm)^-1. Moreover, we reported the photovoltaic aspects of developed Al/n-Si/p-SnS/In solar cell devices. Data from J-V measurements indicated clear dependence on the SnS layer physical characteristics.