Optoelectronic devices combining the high electrical performances of carbon nanotubes with the remarkable optical properties of polymers are demonstrated (see figure). Photoinduced,lambda-dependent, robust, and reversible modulation of the device conductance is achieved. The optical response is based on the trapping of photoexcited electrons at the polymer dielectric interface. Such a nanotube-based device proves a very sensitive probe to study the dynamics and spatial distribution of charges in polymers.