TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The first treatment process includes at least one of anneal, oxidation and etching. The method (M1) further comprises: the step of cleaning and rinsing process before and after applying the first treatment; the step of applying a second treatment process to treat the second buffer film layer, where the second treatment process transforms the second exposed surface into a second treated surface of the first buffer film, and the second treatment process includes at least one of anneal, oxidation and etching; and the step of depositing a third buffer film layer from a third buffer deposition solution onto the second treated top surface (92) of the second buffer film layer, where the third buffer film layer includes cadmium-sulfide. In the method (M1), the first treatment process comprise: step of annealing which is performed in vacuum or inert atmosphere at 30-250 degrees C for a period of 1 second to 30 minutes, where the first treated surface is an annealed surface; oxidation step which is performed in air or oxygen-rich atmosphere with oxygen partial pressure of 0.25-0.50 Atm, where the first treated surface is an oxidized surface; oxidation step which is performed in air or oxygen atmosphere at 30-250 degrees C for a period of 1 second to 30 minutes, where the first treated surface is an oxidized surface; and etching step performed using a liquid etchant, where the first treated surface is an etched surface. In the method (M1), the first treatment process includes the steps of: (a) annealing the absorber and the first buffer film layer in a vacuum or inert atmosphere at a predetermined temperature range, where the steps of annealing transforms the exposed surface to an annealed surface and the step of annealing is performed at 30-250 degrees C for a period of 1 second to 30 minutes; (b) etching the annealed surface using a liquid etchant to form an etched surface; and (c) oxidizing the etched surface in air or oxygen atmosphere to form an oxidized surface. In the method (M1): the step of etching uses a liquid etchant solution with a solvent comprising water, organic liquids, or mixture of water and organic liquids; and the step of oxidation includes a thermal oxidation conducted at 30-250 degrees C for a period of 1 second to 30 minutes. In the method (M1), the liquid etchant is prepared in: an acidic pH of 0-5, which comprises inorganic and organic acids including sulfuric acid, hydrochloric acid, nitric acid, acetic acid, sulfamic acid, citric acid, tartaric acid, acetic acid, boric acid, oxalic acid, phosphoric acid in the molarity concentration of 0.001-1 moles/l; or an alkaline pH of 7-13.5, comprising organic etchant species including maleic acid, oxalic acid, ethylenediamine, tartaric acid, gluconic acid, citric acid, and glycine in the molarity concentration of 0.001-1 moles/l. The alkaline pH is adjusted with addition of sodium hydroxide and potassium hydroxide and with the use of alkaline pH buffers. The liquid etchant solution further employs chemical oxidants including hydrogen peroxide or its derivatives to increase the etch rate. In the method (M2): treating the first buffer layer comprises at least one of oxidizing, etching or annealing the first buffer layer. The method (M2) further comprises: the step of applying a cleaning and rinsing process before and after the treating the first buffer layer; and treating the second buffer layer. In the method (M2): treating the first buffer layer comprises annealing the first buffer layer in vacuum or inert atmosphere at 30-250?Oc for a period of 1 second to 30 minutes, where the outer surface of the first buffer layer is an annealed surface; treating the first buffer layer comprises oxidizing the first buffer layer in an air or oxygen rich atmosphere with oxygen partial pressure of 0.25-0.50 Atm, where the outer layer is an oxidized surface; and treating the first buffer layer comprises etching the first buffer layer using a liquid etchant, where the outer surface of the first buffer layer is an etched surface. In the method (M2): treating the first buffer layer includes the steps (a)-(c) as above per se; the first and second buffer layers are formed by positioning the first and second buffer layers in chemical deposition tanks not necessarily containing either the same material or the same processing temperature; and the buffer layer is deposited in two or more layers to achieve a dense, compact buffer film. Preferred Components: The thickness of the first buffer film layer is 5-1500 Angstrom , and the thickness of the second buffer film layer is 5-1500 Angstrom . The deposition solution used to deposit the first and second film layers include cadmium (0.0005-0.01 M), thiourea (0.001-0.50 M) and ammonia (0.05-3 M). The group IBIIIAVIA absorber layer is a copper indium gallium diselenide absorber layer. In the method (M1): the first buffer deposition solution composition and the second buffer deposition solution composition are the same; and the first solution temperature and the second solution temperature are the same.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic liquid is ethanol, methanol, isopropyl alcohol, acetonitrile or propylene carbonate. EXAMPLE - No suitable example given.