Disclosed is an insulating organic polymer having side chains that enable the formation of a highly hydrophobic insulating layer with decreased surface energy. Decreased surface energy of an organic insulating layer formed using the insulating organic polymer may lead to an increase in the degree of alignment of a semiconductor material. Therefore, the insulating organic polymer may be used to fabricate an organic thin film transistor having improved characteristics, e.g., decreased threshold voltage and increased charge carrier mobility. Further disclosed are an organic insulating layer formed using the insulating polymer, an organic thin film transistor comprising the insulating layer and a method of fabricating the same, and an electronic device comprising the organic thin film transistor.