TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In the method (M1): the depositing is performed using physical vapor deposition (PVD); at least one set of three layers are deposited using three PVD targets, where one PVD target comprises silver and indium, one PVD target comprises copper and gallium, and one PVD target comprises indium, and the PVD target comprising silver and indium comprises less than 21 wt.%% indium, 26-35 wt.% indium, or silver plated indium; and deposition using the PVD target comprising indium is performed in the presence of a chalcogen, or the deposition using the PVD target comprising indium is performed in an inert atmosphere and the target comprises indium(III) selenide or indium sulfide. The method (M1) further comprises grading a bandgap of the absorber layer by varying the atomic ratio of silver to (copper+silver) through the thickness of the precursor film. In the method (M1), at least one set of two layers are deposited using two PVD targets, where one PVD target comprises copper indium gallium alloy of formula (Cu2(InxGa1-x)) and one PVD target comprises indium, where the deposition using the PVD target comprising indium is performed in the presence of a chalcogen, or the deposition using the PVD target comprising indium is performed in an inert atmosphere and the target comprises indium selenide or indium sulfide.x = 0.25In the method (M1): at least one set of two precursor layers are deposited by PVD using two PVD targets, where one PVD target comprises Cu(In,Ga) having an atomic ratio of copper to (indium+gallium) greater than 2 and an atomic ratio of gallium to (gallium+indium) greater than 0.5, where one PVD target comprises indium; and the deposition using the PVD target comprising indium is performed in the presence of a chalcogen, or the deposition using the PVD target comprising indium is performed in an inert atmosphere and the target comprises indium selenide or indium sulfide. In the method (M1): at least one set of three precursor layers are deposited using three PVD targets, where the three PVD targets are: one PVD target comprising copper and gallium, one PVD target comprising copper, and one PVD target comprising indium selenide or indium sulfide, where the layers are deposited in an inert atmosphere; or one PVD target comprising copper and gallium, one PVD target comprising copper, and one PVD target comprises indium, where the layers comprising copper and gallium or copper are deposited in an inert atmosphere, and the layer comprising indium is deposited in an atmosphere comprising at least one of sulfur or selenium. The method (M1) further comprises: grading a bandgap of the absorber layer by varying a ratio of gallium to (gallium+indium) through a thickness of the many precursor layers; and grading a bandgap of the absorber layer by varying a ratio of sulfur to (sulfur+selenium) through a thickness of the layers after the heating. In the method (M2): the process parameters comprise at least one of (in wt.%) indium in silver-indium target, gallium in copper-gallium target, copper in copper-indium-gallium target, gallium in copper-indium-gallium target, copper, silver, indium, and gallium in deposited film or stack of layers, sputtering power, sputtering pressure, sputtering atmosphere composition, sputtering time, number of sets of layers, or co-deposition versus sequential layer deposition; and characterizing each optical absorber comprises measuring a structure or performance parameter of the optical absorber, where the structure or performance parameter is at least one of crystallinity, grain size (distribution), lattice parameter, crystal orientation (distribution), matrix and minority composition, bandgap, bandgap grading, bulk bandgap, surface bandgap, efficiency, resistivity, carrier concentration, mobility, minority carrier lifetime, optical absorption coefficient, surface roughness, adhesion, thermal expansion coefficient, thickness, photoluminescence properties, surface photovoltage properties, haze, gloss or specular reflection. Preferred Components: The chalcogen comprises at least one of sulfur or selenium. An overall composition of the precursor layers has a composition defined by atomic ratios of: ((copper+silver)/(indium+gallium)) is less than 1, preferably greater than 0.7-1; (gallium/(indium+gallium)) is less than 0.5, preferably greater than 0 to 0.5; and (silver/(copper+silver)) is greater than 0.05 to 0.3. The precursor layers comprise at least one set of two or three layers. The copper and gallium target comprises less than 45 wt.% gallium. EXAMPLE - No suitable example given.