Highly fluorescent emitters based on triphenylamine‐π‐triazine (D‐π‐A) system : effect of extended conjugation on singlet‐triplet energy gap

Abstract

Three D‐π‐A type linearly‐extended emitters, based on diphenylamine ( DPA ) as the donor and 2,4,6‐triphenyl‐1,3,5‐triazine ( TRZ ) as the acceptor, were synthesized and their optoelectronic properties characterized. The introduction of an additional phenyl or phenylethynyl π‐spacer results in an enhancement of the molar extinction coefficient and a systematic bathochromic shift of the charge‐transfer transition in the absorption spectra. A mirrored bathochromic shift in the photoluminescence spectra is also observed with increasing conjugation of the bridge moiety. All three compounds show high photoluminescence quantum yields and moderate singlet‐triplet excited state energy gaps, ΔE ST, of 0.26‐0.37 eV were observed in 10 wt% doped films in mCP as the host matrix.