<p>Selenium is regarded as an important photovoltaic material owing to its excellent physical and chemical properties. In the present study, Se_{85−<i>x</i>}Ga₁₅Bi_<i>x</i> (<i>x</i> = 0, 2, and 4) bulk materials were synthesized by the melt-quenching technique, and thin films of these bulk materials were deposited by vacuum thermal evaporation. The x-ray diffraction pattern confirmed the crystalline phase in the bulk form and amorphous nature in the thin film form for these compositions. The Raman spectra established the presence of different modes. The microstructural analysis by scanning electron microscopy (SEM) revealed the presence of dense, spherical particles. The optical properties of pristine and Bi-doped Se₈₅Ga₁₅ were studied in the wavelength range of 300–1100&#xa0;nm. It was observed that the optical bandgap varied from 1.43&#xa0;eV to 1.26&#xa0;eV in pristine and Bi-substituted Se₈₅Ga₁₅ thin films due to an increase in deep-level defects. The direct current (DC) conductivity revealed an enhancement in dark conductivity and photoconductivity due to the increase in Bi concentration. The dependence of photocurrent on light intensity confirmed the bimolecular recombination mechanism. The transient-state photoconductivity revealed a decrease in the carrier lifetime and an increase in the defect state with the incorporation of Bi.</p>