David J. Harkin, Katharina Broch, Maximilian Schreck, Harald Ceyman, Andreas Stoy, Chaw-Keong Yong, Mark Nikolka, Ian McCulloch, Natalie Stingelin, Christoph Lambert, Henning Sirringhaus

• Fluorescence enhancement of a high-mobility polymer semiconductor is achieved via energy transfer to a higher fluorescence quantum yield squaraine dye molecule on 50 ps timescales. In organic light-emitting diodes, an order of magnitude enhancement of the external quantum efficiency is observed without reduction in the charge-carrier mobility resulting in radiances of up to 5 W str\(^{-1}\) m\(^{-2}\) at 800 nm.