NOVELTY - Controlling a self-assembled structure of a poly(3-hexylthiophene)-based block copolymer involves: preparing a polymer composition containing a block copolymer having a pi -conjugated poly(3-hexylthiophene) polymer and a non-conjugated polymer introduced to it, and a solvent; and coating the polymer composition onto a substrate.    USE - For controlling a self-assembled structure of a poly(3-hexylthiophene)-based block copolymer useful in an organic electronic device selected from an organic field-effect transistor (OFET) or a photovoltaic cell (claimed).    ADVANTAGE - By using the method, it is possible to control a self-assembled structure of a poly(3-hexylthiophene)-based block copolymer so that it is suitable for providing various organic electronic devices with high quality, merely by a relatively simple process including coating the poly(3-hexylthiophene)-based block copolymer onto a substrate with a selected solvent to a certain thickness. It is also possible to apply the self-assembled polymer structures having various self-assembled structures controlled selectively by the method to general organic electronic devices for designing and developing high-quality devices. By using the method, it is possible to control the alignment of poly(3-hexylthiophene) crystal domains through the control of a self-assembled structure of a poly(3-hexylthiophene)-based block copolymer merely by carrying out a simple solution process using a selected solvent, and thus to produce self-assembled polymer structures suitable for high-quality organic electronic devices. As a result, it is possible to obtain polymer structures by a simplified process with high productivity at low cost. The self-assembled structure of the poly(3-hexylthiophene)-based block copolymer is controlled so that the poly(3-hexylthiophene) crystal domains have structures oriented with parallel direction to a substrate, thus it is possible to realize high quality in a top gate type organic field effect transistor, or the poly(3-hexylthiophene) crystal domains are formed with face-on alignment to the substrate, thus it is possible to transport holes easily to negative electrodes of organic photovoltaics (OPV), and thus realizes excellent quality in organic photovoltaics. Therefore, the self-assembled polymer structure including the alignment-controlled poly(3-hexylthiophene) crystal domains is useful for designing and developing various high-quality devices. By using the method, it is possible to improve the efficiency of organic photovoltaics significantly by applying the self-assembled polymer structure. Particularly, the method controls the molecular alignment of a conductive block copolymer through a single process using a desired solvent instead of using a large number of processes. As a result, the method allows reduction of a hole transport distance to a lower electrode using self-assembled p-type face-on domains having a diameter of less than or equal to 30 nm.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a self-assembled polymer structure comprising a pi -conjugated poly(3-hexylthiophene)-based block copolymer, which has a self-assembled structure controlled by coating a polymer composition containing a block copolymer having a non-conjugated polymer introduced to the poly(3-hexylthiophene) polymer and a solvent, onto a substrate.