Design and Synthesis of Donor−σ–π–σ–Acceptor-Type Dispiro Molecules

Two novel donor−σ–π–σ–acceptor-type dispiro molecules—10-phenyl-10H-dispiro-acridine-9,9′-anthracene-10′,9′′-fluorene-2′′,7′′-dicarbo-nitrile (DiSAAF) and dispiro-fluorene-9,9′-anthracene-10′,9′′-quinolino[3,2,1-kl]phenoxazine-2,7-dicarbonitrile (DiSFAQ)—with excellent thermal stability are designed and synthesized. Both materials exhibit blocked long-range intramolecular charge transfer but show intermolecular charge-transfer emission in the film state. Their photophysical and thermal properties then are fully investigated and a maximum external quantum efficiency of 21.7% of the red phosphorescent device is achieved by DiSAAF.