TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Processes: Photovoltaic device is fabricated by forming n-type buffer layer on a side of Sb-doped absorber layer opposite the substrate, forming transparent conductive contact on a side of buffer layer opposite the Sb-doped absorber layer, and forming metal grid on a side of transparent conductive contact opposite the buffer layer. Molybdenum, tungsten, or chromium is sputtered on the substrate to a thickness of 0.5-1 microns. Sb-doped absorber layer is formed by preparing Sb-doped nanoparticle precursor ink, depositing Sb-doped nanoparticle precursor ink on substrate, and annealing Sb-doped nanoparticle precursor ink deposited on substrate under helium selenide (H2Se). Sb-doped nanoparticle precursor ink is prepared by adding elemental Sb to copper (Cu), indium (In), and gallium (Ga) pre-mixture in acid. Preparation of Sb-doped nanoparticle precursor ink includes adding acid-soluble Sb-containing compound to Cu, In, and Ga pre-mixture in acid. Sb-doped nanoparticle precursor ink is deposited on substrate by doctor blading, ink jet printing, roller coating, spraying, stamping, and/or dip coating. Sb-doped absorber layer is formed by depositing separately an Sb-source thin film and a film containing Cu, In, Ga, and/or Se on the substrate by vacuum deposition technique. Sb-source thin film is deposited before or after the film containing Cu, In, Ga, and/or Se. Relative ratio of Sb-source thin film and film containing Cu, In, Ga, and/or Se is varied to vary Sb content in the Sb-doped absorber layer. Preferred Components: Substrate contains glass, metal foil, or polyimide sheet. Acid-soluble Sb-containing compound contains antimony oxide. Sb-source thin film contains Sb, antimony sulfide (Sb2S3), or antimony selenide (Sb2Se3) thin film. Preferred Parameters: Sb-doped absorber layer has grain size of 0.2-2 microns measured as a longest length of a grain from a cross-section of the Sb-doped absorber layer. Longest length of the grain from the cross-section of the Sb-doped absorber layer is greater than or equal to a thickness of the Sb-doped absorber layer. Sb-doped absorber layer has a thickness of 200 nm to 2.5 microns.