NOVELTY - The method comprises coating an organic electronic device fabricated on a flexible glass substrate (1) or on a top or both the top and bottom of a plastic substrate with a photocurable polymer, curing the coated photocurable polymer by a UV/ozone (UV/O3) process to form an organic polymer passivation layer, and depositing a nanocomposite material containing two inorganic materials on the organic polymer passivation layer to form an inorganic thin film passivation layer. The photocurable polymer is coated by spin coating, screen printing, bar coating, inkjet printing, or dipping.    USE - The method is useful for fabricating an organic/inorganic hybrid thin film passivation layer for blocking moisture and oxygen transmission and improving gas barrier property of an organic electronic device (claimed) such as organic light emitting diodes, organic thin-film transistors and solar cells.    ADVANTAGE - The method is capable of rapidly and economically fabricating a high quality organic/inorganic hybrid thin film passivation layer thus effectively blocking the oxygen and moisture transmission of the organic electronic device, ensuring the stability and reliability of the device and improving the gas barrier property of the plastic substrate, improves the adhesion strength between the passivation layer interfaces, and increases the light transmission rate due to surface planarization of the organic polymer passivation layer.    DETAILED DESCRIPTION - The method comprises coating an organic electronic device fabricated on a flexible glass substrate (1) or on a top or both the top and bottom of a plastic substrate with a photocurable polymer, curing the coated photocurable polymer by a UV/ozone (UV/O3) process to form an organic polymer passivation layer, and depositing a nanocomposite material containing two inorganic materials on the organic polymer passivation layer to form an inorganic thin film passivation layer. The photocurable polymer is coated by spin coating, screen printing, bar coating, inkjet printing, or dipping. The coated photocurable polymer has a thickness of 0.1-10 mu m. The UV/ozone process includes pre-curing, UV/ozone irradiation, and heat curing. The pre-curing is carried out by treating the photocurable polymer at a temperature of 70-90 degrees C for 2-5 minutes. The UV/ozone irradiation is carried out by irradiating the precured photocurable polymer with a light source having an energy of 2400-3000 mJ/cm2 at a wavelength of 170-200 nm for 1-7 minutes to degrade oxygen molecules into oxygen atoms followed by irradiation with a light source having an energy of 2400-2700 mJ/cm2 at a wavelength of 240-270 nm for 1-7 minutes to generate ozone from the oxygen atoms. The heat curing is carried out by treating the UV/ozone irradiated photocurable polymer at a temperature of 100-120 degrees C for 1-2 hours. The nanocomposite material is a mixture containing two inorganic materials. The deposition of the nanocomposite material is carried out by an electronbeam evaporator, a sputter, physical vapor deposition, chemical vapor deposition or atomic layer deposition. The deposited nanocomposite material has a thickness of 0.1-0.5 mu m. The coating, curing, and the depositing are repeatedly carried out in order, so as to form a pair of the organic polymer passivation layer and inorganic thin film passivation layer in a multilayer laminate structure. An INDEPENDENT CLAIM is included for an organic/inorganic hybrid thin film passivation layer for blocking oxygen and moisture transmission of an organic electronic device fabricated on a substrate and improving gas barrier properly of a plastic substrate.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a structure of an organic electronic device fabricated on a substrate.    Glass substrate (1)    Hole injection layer (2)    Hole transfer layer (3)    Light emitting layer (4)    Electron transfer layer (5)    Electron injection layer. (6)