An organic electronic device comprising an anode, a cathode, a semiconducting layer between the anode and the cathode and a hole transporting layer between the anode and the semiconducting layer, the hole-transporting layer comprising a co-polymer comprising repeat units of formula (I) and one or more co-repeat units: (I) wherein: Ar1 independently in each occurrence represents a fused aryl or fused heteroaryl group that may be unsubstituted or substituted with one or more substituents; Ar2 represents an aryl or heteroaryl group that may be unsubstituted or substituted with one or more substituents; R independently in each occurrence represents a substituent; and m is 1 or 2, preferably 1; and each Ar1 is directly bound to an aromatic or heteroaromatic group of a co-repeat unit.