The transient decays show a quenching of the delayed emission in air. The prompt and delayed lifetimes, τp and τd, are 1.9 ns and 11 µs in degassed toluene solution; the delayed emission is not detectable in aerated solution. All these results imply contributions from triplet excitons. By contrast, delayed emission was not observed in toluene solutions of DiKTa and tBuDOBNA. a Measured in toluene solution at a concentration of 1×10 -5 M; b Measured in spin-coated 1.5 wt% doped thin films in mCP. c the FPL of the solution was measured using the optically dilute method and of the film was measured using an integrating sphere under nitoigen (lexc =340 nm). d Obtained at 298 K, lexc = 340 nm. e Full-width at half-maximum; f Obtained from the onset of the SS PL spectrum at 77 K.