Methods of preparing a polymer solution for organic electrochemical transistor preparation include preparing a solvent solution, preparing a dopant solution, and combining the solvent solution and the dopant solution at 60 to 90 volume percent solvent solution and 10 to 40 volume percent dopant solution. Preparing the solvent solution includes degassing a first solvent to form a degassed first solvent and combining the degassed first solvent with a polymer. Preparing the dopant solution includes degassing a second solvent to form a degassed second solvent and combining the degassed second solvent with a p-dopant.

A semiconductor device according to the present invention includes a substrate, a plurality of electrodes on the substrate, an insulator provided with one or a plurality of openings exposing at least one electrode among the plurality of electrodes on the substrate, the insulator covering at least a portion of the plurality of electrodes, and a semiconductor sheet on the insulator and one or a plurality of exposed portions exposed from the one or the plurality of openings on the substrate.

A semiconductor device according to the present invention includes a substrate, a plurality of electrodes on the substrate, an insulator provided with one or a plurality of openings exposing at least one electrode among the plurality of electrodes on the substrate, the insulator covering at least a portion of the plurality of electrodes, and a semiconductor sheet on the insulator and one or a plurality of exposed portions exposed from the one or the plurality of openings on the substrate.