Living Radical Polymerization of Bipolar Transport Materials for Highly Efficient Light Emitting Diodes

The synthesis of hole transport, electron transport, and functionalized β-diketone monomers, as well as their living radical polymerization, is described. Utilizing a second-generation nitroxide initiator allows the polymerization of homopolymers, as well as random and block co- and terpolymers, with predictable molecular weights and low polydispersities. These highly soluble polymers bearing bipolar transport moieties can either be used directly as a matrix for doping with luminescent molecules or be functionalized with phosphorescent iridium or platinum complexes. The flexibility of polymer construction and functionalization translates into versatility in the design and the tuning of functional properties of solution-processed organic light emitting diodes. Devices emitting white light with maximum front face external quantum efficiency (EQE) of 4.9% and devices having green emission with maximum EQE of 10.5% have been achieved.