An organic semiconductor device selected from organic diodes, organic field effect transistors, and devices comprising an organic diode and/or organic field effect transistor and a method of producing such a device are provided. The organic semiconductor device comprises at least one semiconducting layer based on a diketopyrrolopyrrole (DPP) polymer. The semiconducting layer may effectively be protected against degradation by radiation and/or oxidation by adding at least one stabilizing agent selected from hydroxybenzophenones, hydroxyphenyl benzotriazoles, oxalic acid anilides, hydroxyphenyl triazines, hindered phenols and/or merocyanines to the DPP polymer layer. The stabilization is effective both during production and during usage of the device, while the device's electronic properties are retained. The stabilizing agent is preferably a UV absorbing agent or an antioxidant or anti-radical agent known from the field of organic polymer technology.