TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (claimed): The film (I) is formed by:(A) dissolving copper (Cu) source, indium (In) source, gallium (Ga) source, selenium (Se) source and Sb source in hydrazine to form solutions and mixing solutions to form Sb-doped absorber layer precursor solution, spin-coating on substrate, annealing, repeating spin-coating and annealing steps until achieving desired thickness, and performing final anneal;(B) adding elemental Sb or acid-soluble Sb-containing compound to Cu, In and Ga pre-mixture in acid to form Sb-doped nanoparticle precursor ink, depositing on substrate and annealing under hydrogen selenide; or(C) depositing separately Sb-source thin film and film comprising Cu, In, Ga and/or Se on substrate through vacuum deposition.Preferred Parameter: The film (I) has grain size of 0.2-2 (preferably 0.5-1) mu m. The absorber layer has thickness of 1-2.5 mu m. Preferred Method: The method further comprises forming negative-type buffer layer (106) on side of absorber layer opposite the substrate, forming transparent conductive contact (108) on side of buffer layer opposite the absorber layer, and forming metal grid (110) on side of transparent conductive contact opposite the buffer layer. Preferred Components: The substrate comprises glass, metal foil or polyimide sheet coated with molybdenum, tungsten or chromium at thickness of 0.5-1 mu m. The buffer layer comprises cadmium sulfide (CdS) and zinc-doped CdS. The transparent conductive contact comprises bilayer of zinc oxide (ZnO) with aluminum-doped ZnO or indium tin oxide. The Sb-source thin film comprises Sb, stibnite or antimony selenide thin film. SPECIFIC COMPOUNDS - (5) Compounds (I) are specifically claimed comprising Cu0.82In0.7Ga0.3Sb0.002Se2, CuIn0.7Ga0.3Sb0.0025Se2, CuIn0.7Ga0.3Sb0.005Se2, CuIn0.7Ga0.3Sb0.01Se2 or Cu0.85In0.7Ga0.3Sb0.005Se2.    EXAMPLE - An absorber layer comprising Cu0.82In0.7Ga0.3Sb0.002Se2 was prepared by forming component solution in nitrogen-filled glove box with water and oxygen levels maintained below 1 ppm including mixing copper sulfide (Cu2S, 10 mmol), sulfur (S, 20 mmol) and 98% anhydrous hydrazine (20 mL) to form clear yellow Cu2S solution, mixing indium selenide (In2Se3, 10 mmol), selenium (Se, 10 mmol) and 98% anhydrous hydrazine (30 mL) to form viscous pale yellow In2Se3 solution, mixing gallium (Ga, 8 mmol) and Se (16 mmol) in 98% anhydrous hydrazine (16 mL) for 1 week to form colorless gallium selenide (Ga2Se3) solution, mixing Se (10 mmol) in 98% anhydrous hydrazine (5 mL) to form darkly colored Se solution and mixing stibnite (Sb2S3, 1 mmol), S (2 mmol) and 98% anhydrous hydrazine (2 mL) for 2 days to form clear bright yellow Sb2S3 solution, adding prepared Sb2S3 solution (3 mu L) to mixed solution (4.62 mL) comprising (parts per volume) Cu2S solution (3.69), In2Se3 solution (4.725), Ga2Se3 solution (2.7) and Se solution (0.9), stirring at room temperature for 1 day to obtain precursor solution, spin-coating into 2 films at 800 rpm for 90 seconds on glass/molybdenum substrate, drying and decomposing partially at 290 degrees C for 5 minutes in inert atmosphere, depositing additional 9 layers and performing final anneal at 525 degrees C for 15 minutes. A photovoltaic device was fabricated by depositing cadmium sulfide (CdS) buffer layer at thickness of 50 nm on prepared absorber layer opposite the substrate, sputtering high resistivity intrinsic zinc oxide on CdS at thickness of 70 nm, depositing with indium tin oxide (ITO) layer at thickness of 200 nm to form transparent conductive top contact and forming nickel (Ni)/aluminum (Al) metal grid having thickness of 50 nm for Ni and 2 mu m for Al on top of ITO layer to facilitate current collection. The device had open circuit voltage (Voc) of 0.57 V, short circuit current density (Jsc) of 30.3 mA/cm2 and overall efficiency (Eff) of 12.3% being superior compared to that of device prepared with absorber layer without antimony dopant having Voc of 0.55 V, Jsc of 27.7 mA/cm2 and Eff of 10.3%.