Emission Color Trajectory and White Electroluminescence Through Supramolecular Control of Energy Transfer and Exciplex Formation in Binary Blends of Conjugated Polyrotaxanes

White electroluminescence and fine-tuning of the emission color from binary blends of a blue-emitting polymer and a green/yellow-emitting threaded molecular wire consisting of a conjugated polymer supramolecularly encapsulated by functionalized cyclodextrins are demonstrated. Encapsulation controls the minimum intermolecular distance on the nanoscale, resulting in suppressed energy-transfer between the blend constituents and reduced formation of interchain charge-transfer complexes. The use of a green-emitting polyrotaxane significantly improves the electrical properties with respect to blends of a blue electroluminescent polyrotaxane and leads to a significant reduction in the turn-on voltage required for achieving white electroluminescence (VON = 3 V), with only 20% by weight of the encapsulated material.