Thin-film transistors and techniques for forming thin-film transistors (TFT). In some embodiments, there is provided a method of forming a TFT, comprising forming a body region of the TFT comprising an organic semiconducting material, and forming a protective layer comprising an organic insulating material. Forming the protective layer comprises contacting the body region of the TFT with a solution comprising the organic insulating material. The organic insulating material is a material that phase separates with the organic semiconducting material when the solution contacts the organic semiconducting material. In other embodiments, there is provided an apparatus comprising a TFT. The TFT comprises a body region comprising an organic semiconducting material and a protective layer contacting the body region and comprising an organic insulating material that, when a solution comprising the organic insulating material contacts the organic semiconducting material, causes the organic insulating material to phase separate with the organic semiconducting material.