NOVELTY - Aqueous inorganic coating precursor solution comprises a mixture of water, polynuclear aluminum hydroxide cations and polyatomic ligands comprising nitrate and/or nitrite, where the composition has a molar concentration ratio of polyatomic ligands to aluminum of less than 3.    USE - The aqueous inorganic coating precursor solution is useful for forming: a thin film aluminum oxide on a substrate; a coating on a crystalline silicon solar cell; and an electronic device including field effect transistor or a capacitor (all claimed).    ADVANTAGE - The precursor solution provides high quality aluminum oxide films with significantly higher density, lower contaminant levels, high level of uniformity and smoother surfaces, compared to other solution based processes.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) method (I) of forming an aqueous inorganic coating precursor solution, comprising adding a metal having a sufficient reduction potential to reduce nitric acid to an aqueous solution comprising aluminum nitrate, where the molar concentration of aluminum is 0.01-3.5 M and zinc: aluminum ratio is 0.01:1-3:1;    (2) method (II) for forming a thin film aluminum oxide on a substrate, comprising: forming a layer of the precursor coating material on a substrate, thus forming a coated substrate; heating the coated substrate to remove the polyatomic ligands and at least a portion of the water; and heating the coated substrate within a temperature of 100-900 degrees C to eliminate water and to form and densify a thin film of aluminum oxide on the substrate;    (3) method (III) of forming a coating on a crystalline silicon solar cell, comprising: providing a crystalline silicon substrate having a front side and a back side; depositing the coating precursor solution, on the front side of the crystalline silicon substrate, on the back side of the crystalline substrate or on both sides; and forming a dielectric aluminum oxide film on at least one of the front and the back side by annealing the coating precursor at a temperature of 80-900 degrees C, where the aluminum oxide film has a thickness of 0.5-100 nm; and    (4) method (IV) for forming an electronic device comprising an aluminum oxide dielectric film, where the dielectric film is manufactured by a method comprising: depositing the coating precursor solution onto a substrate; and forming a dielectric aluminum oxide film at 80-900 degrees C.