Above 20% external quantum efficiency in thermally activated delayed fluorescence device using furodipyridine-type host materials

High efficiency green thermally activated delayed fluorescence device with a quantum efficiency above 20% was developed using a bipolar host material, 3-(furo[2,3-b:5,4-b′]dipyridin-3-yl)-N,N-diphenylaniline (3TPAPFP), derived from furodipyridine core structure. The furodipyridine based 3TPAPFP showed a singlet and triplet energy for efficient energy transfer to thermally activated delayed fluorescent dopant, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl) isophthalonitrile (4CzIPN), and bipolar charge transport properties for balanced hole and electron density. A high quantum efficiency of 21.2% was achieved in the fluorescent device using the 3TPAPFP host doped with 4CzIPN dopant at a very low doping concentration of 1%.