Disclosed herein is a composition including a perfluoropolyether derivative, a photosensitive polymer or a copolymer thereof, and a photocuring agent, a passivation layer, organic thin film transistor, and electronic device including the same, a method of forming the passivation layer and methods of fabricating the organic thin film transistor and electronic device. The organic thin film transistor may prevent or reduce oxygen and moisture from infiltrating thereinto, and thus may prevent or reduce the degradation of the performance thereof caused by ambient air, prevent or reduce the deterioration thereof, and may more easily be formed into a pattern, thereby exhibiting characteristics suitable for use in electronics.