Dispiro and Propellane: Novel Molecular Platforms for Highly Efficient Organic Light-Emitting Diodes

The incorporation of spatially oriented aromatic motifs in rigid molecular platforms is of great interest for the design of organic electronic materials. These structures can create unusual packing patterns and charge transport properties in the solid state which are not possible for simple planar structures. Herein, we showed that the novel dispiro and propellane motifs were successfully used as robust molecular platforms for the construction of host materials (TPA, Cz, SF, and SO). The propellane derivative with three functional groups arranged in the staggered conformation was studied for the first time as the host for organic light-emitting diodes (OLEDs). The green and red phosphorescent OLEDs hosted by these dispiro and propellane derivatives exhibited excellent electroluminescence performance. Particularly, the red OLED hosted by the propellane-type SF achieved maximum efficiencies of 47.3 cd A^-1, 40.2 lm W^-1, and 26.6% and 97.6 cd A^-1, 77.8 lm W^-1, and 27.0% for the green OLED without any light out-coupling enhancement. These results suggest that the dispiro and propellane molecular platforms have great potential in the construction of OLED materials.