A major loss mechanism in high intensity organic light-emitting devices is the quenching of excitons in the presence of polarons. In this work, the interaction of excitons in N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) with holes in pentacene is studied in a pentacene/NPB bilayer organic field-effect transistor. Gate-modulated steady-state photoluminescence quenching measurements are performed. The excitons are confined in NPB and the polarons in an ultrathin layer of pentacene at the pentacene/NPB organic heterojunction. It is shown that excitons are quenched by polarons, even if they are located on different materials, provided that the exciton and polaron are separated by a length within which efficient Förster resonance energy transfer can occur. The experimental findings are supported by a steady-state three-dimensional simulation of the gate voltage-dependent exciton-polaron quenching efficiency. The Förster resonant energy transfer radius for exciton-polaron interaction at the pentacene/NPB heterojunction is estimated to be in the range of 2.3-3.0 nm. © 2021 American Chemical Society.