NOVELTY - The apparatus comprises a nanostructure (180) such as a nanowire and an inorganic nanolayer, a focused electron beam-irradiating unit (100) that serves to irradiate a nanoscale electron beam to be focused on the nanostructure, and a focused electron beam-controlling unit (190) that serves to control an irradiation position of the nanoscale electron beam to modify a physical property of a portion of the nanostructure. The nanostructure is a pi -conjugated polymer nanostructure or an inorganic nanostructure. The pi -conjugated polymer nanostructure is formed of a light-emitting polymer material.    USE - The apparatus is useful for modifying a physical property such as structural properties, photoluminescent properties, lattice defects, doped states and electrical properties of a nanostructure such as nanowires, nanorods, nanotubes, nanoplates, an inorganic nanolayer and nano-barcode using a focused electron beam (all claimed), where the nanostructures are useful for the fabrication of organic photoelectric devices such as organic LEDs, organic FETs and organic solar cells.    ADVANTAGE - The apparatus ensures easy, energy efficient and accurate modification of physical property of the nanostructure thus ensuring economical production of organic photoelectric devices with high productivity.    DETAILED DESCRIPTION - The apparatus comprises a nanostructure (180) such as a nanowire and an inorganic nanolayer, a focused electron beam-irradiating unit (100) that serves to irradiate a nanoscale electron beam to be focused on the nanostructure, and a focused electron beam-controlling unit (190) that serves to control an irradiation position of the nanoscale electron beam to modify a physical property of a portion of the nanostructure. The nanostructure is a pi -conjugated polymer nanostructure or an inorganic nanostructure. The pi -conjugated polymer nanostructure is formed of a light-emitting polymer material or a conductive polymer material. The focused electron beam-irradiating unit is a scanning electron microscope, a transmission electron microscope and an electron-beam lithography system. The electron beam has a diameter of greater than or equal to 1 nm, and is focused to a size of less than or equal to 1000 nm. The focused electron beam-controlling unit controls the irradiation position so that: portions irradiated with the electron beam and not irradiated with the electron beam are formed alternately along the nanowire; and the inorganic nanolayer is irradiated with the electron beam to form a two-dimensional pattern. INDEPENDENT CLAIMS are included for:    (1) a method of modifying a physical property of a nanostructure;    (2) a pi -conjugated polymer nano-barcode;    (3) a series-junction polymer nanowire; and    (4) an inorganic nano-barcode.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an apparatus for modifying the physical properties of a nano-structure.    Electron beam-irradiating unit (100)    Stigmator/deflection coil (140)    Substrate (160)    Nanostructure (180)    Electron beam-controlling unit. (190)