The present invention relates integrated optoelectronic devices comprising light emitting field-effect transistors. We describe an optoelectronic device comprising a light-emitting field effect transistor (LFET) with an organic semiconductor active layer and a waveguide integrated within the channel of the light-emitting field effect transistor, wherein said waveguide comprises a material which has a higher refractive index than said organic semiconductor. We also describe a light-emitting organic field transistor integrated with a ridge or rib waveguide incorporated within the channel of the LFET; and a similar light-emitting organic field effect transistor in which the waveguide incorporates an optical feedback mechanism.