The aggregation-induced emission (AIE) phenomenon provides a new direction for the development of organic light-emitting devices. Here, we present a new class of emitters based on 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY), functionalized at different positions with tetraphenylethylene (TPE), which is one of the most famous AIE luminogens. Thanks to this modification, we were able to tune the photoluminescence of the BODIPY moiety from the green to the near-infrared (NIR) spectral range and achieve PL efficiencies of ~50% in the solid state. Remarkably, we observed an enhancement of the AIE and up to ~100% photoluminescence efficiencies by blending the TPE-substituted BODIPY fluorophores with a poly[(9,9-di-n-octylfluorene-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)] (F8BT) matrix. By incorporating these blends in organic light-emitting diodes (OLEDs), we obtained electroluminescence peaked in the range 650–700 nm with up to 1.8% external quantum efficiency and ~2 mW/cm2 radiance, a remarkable result for red/NIR emitting and solution-processed OLEDs.
This work was supported by the European Community’s Seventh Framework Programme (FP7/2007-2013) (607585). S.B. and S.A. thanks Stefan Türk from MPI, Anke Helfer and Sylwia Adamczyk from Bergische Universität Wuppertal for mass and AFM characterizations. S.B. and S.A. thank Dr. Michael Forster from BUW for the helpful discussions. S.B. thanks Prof. Ullrich Scherf and Bergische Universität Wuppertal for the financial support. F.C. is a Royal Society Wolfson Research Merit Award holder.