The interaction between photoexcited excitons and field induced charges in poly(3-hexylthiophene) has been studied using photoluminescence. Thin films of poly(3-hexylthiophene) and Langmuir-Blodgett films of poly(3-hexylthiophene)/Arachidic acid show a quenching of the photoluminescence intensity upon charge injection in a field effect device. The quenching is discussed in terms of polarons/bipolarons acting as recombination centra for the excitons, giving non-radiative decay. The rate constant for non-radiative recombination of the excitons is shown to be proportional to the number of injected charges. This field effect luministor device shows the coupling between the optical and electronic properties of excitations in conjugated polymers.