NOVELTY - Organic solar cell (10) comprises: a cathode (5); an anode (3) disposed substantially opposite the cathode; a photoactive layer (11) disposed between the cathode and the anode; and an electron blocking layer (21) disposed between the anode and the photoactive layer, where the photoactive layer comprises an electron donor, an electron acceptor disposed adjacent to the electron donor, and a nanostructure disposed adjacent to at least one of the electron donor and the electron acceptor.    USE - Used as an organic solar cell.    ADVANTAGE - The organic solar cell: has increased photocurrent and improved photoelectric conversion efficiency by improving a path for the movement of holes in the photoactive layer; and can be fabricated with high efficiency in a simple manner and with low cost.    DETAILED DESCRIPTION - Organic solar cell (10) comprises: a cathode (5); an anode (3) disposed substantially opposite the cathode; a photoactive layer (11) disposed between the cathode and the anode; and an electron blocking layer (21) disposed between the anode and the photoactive layer. The photoactive layer comprises: an electron donor; an electron acceptor disposed adjacent to the electron donor; and a nanostructure disposed adjacent to at least one of the electron donor and the electron acceptor, where the nanostructure is connected to the anode, and comprises a hole transporting material including a semiconductor element, a semiconductor compound and/or semiconductor carbon material, which satisfy the following equation 1 (modulus of LUMO(A) is greater than the modulus of CBE(N)) and equation 2 (modulus of HOMO(D) is greater than the modulus of VBE(N)), where LUMO(A) is an energy level of a lowest unoccupied molecular orbital of the electron acceptor, CBE(N) is a conduction band edge of the nanostructure, HOMO(D) is an energy level of a highest occupied molecular orbital of the electron donor, and VBE(N) is a valance band edge of the nanostructure. INDEPENDENT CLAIMS are also included for:    (1) an organic solar cell comprising the cathode, the anode, the photoactive layer and the electron blocking layer, where the photoactive layer comprises the electron donor, the electron acceptor and the nanostructure, in which some of the nanostructure is connected to the anode and comprises the hole transporting material, and the rest of the nanostructure is connected to the cathode and comprises an electron conductive material including semiconductor element, semiconductor compound, semiconductor carbon material, a metallic carbon material which is surface-treated with a hole blocking material and/or a metal which is surface-treated with a hole blocking material; and    (2) fabricating the organic solar cell, comprising: either (a) providing the anode on a substrate, (b) providing the nanostructure on the anode so that the nanostructure is arranged substantially perpendicular to the anode, and at the same time providing the electron blocking layer on the anode, (c) coating a mixed solution of an electron donor and an electron acceptor on the nanostructure to form the photoactive layer, and (d) providing the cathode on the photoactive layer; or (a) as above per se, (b1) providing an electron blocking layer on the anode, (c1) providing a nanostructure on the electron blocking layer so that the nanostructure is arranged substantially perpendicular to the electron blocking layer, (c) as above per se, and (d) as above per se.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of the organic solar cell.    Anode (3)    Cathode (5)    Organic solar cell (10)    Photoactive layer (11)    Electron blocking layer (21)