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, ΔEST, of 0.26‐0.37 eV were observed in 10 wt% doped films in PMMA as the host matrix.

Electron-withdrawing Group Modified Carbazolophane Donors for Deep Blue Thermally Activated Delayed Fluorescence OLEDs

“…The S1 energies in PPT are only slightly lower in energy than those determined in PMMA (S1 = 3.0 eV), Figure S8. The T1 levels remain largely the same, regardless of the nature of the host medium or the structure of the emitter, and are of similar magnitude to their corresponding triphenyl triazine acceptor segments in toluene, 32 indicating that the T1 state is locally excited ( 3 LE) character. The T1 levels for CF3CzpPhTRZ, CNCzpPhTRZ and CzpPhTRZ are all around 2.69 eV in PPT (Figure 6) and closely resembles those measured in PMMA at 2.73 eV (Figure S8) and the reported triplet energy of CzpPhTRZ in DPEPO (2.73 eV).…”

Electron-withdrawing Group Modified Carbazolophane Donors for Deep Blue Thermally Activated Delayed Fluorescence OLEDs

“…6, the S 1 levels of †). The T 1 levels remain largely the same, regardless of the nature of the host medium or the structure of the emitter, and are of similar magnitude to their corresponding triphenyl triazine acceptor segments in toluene, 32 indicating that the T 1 state is locally excited ( 3 LE) character. The T 1 levels for CF 3 CzpPhTRZ, CNCzpPhTRZ and CzpPhTRZ are all around 2.69 eV in PPT (Fig.…”

Electron-withdrawing group modified carbazolophane donors for deep blue thermally activated delayed fluorescence OLEDs

“…The S 1 energies in PPT are only slightly lower in energy than those determined in PMMA (S 1 = 3.0 eV), FigureS9. The T 1 levels remain largely the same, regardless of the nature of the host medium or the structure of the emitter, and are of similar magnitude to their corresponding triphenyl triazine acceptor segments in toluene,32 indicating that the T 1 state is locally excited ( 3 LE) character. The T 1 levels for CF 3 CzpPhTRZ, CNCzpPhTRZ and CzpPhTRZ are all around 2.69 eV in PPT (Figure6) and closely resembles those measured in PMMA at 2.73 eV (FigureS9) and the reported triplet energy of CzpPhTRZ in DPEPO (2.73 eV) 18.…”