Abstract
AbstractThree 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.
Highlights
Activated delayed fluorescence (TADF) emitters have become very popular alternatives to phosphorescent organometallic complexes for organic light-emitting diodes (OLEDs) because this class of materials can likewise recruit both singlet (25%) and triplet (75%) excitons to produce light.[1,2] Thermally activated delayed fluorescence (TADF) compounds accomplish this through thermal upconversion of triplet excitons into singlet excitons, a process made possible [a] Dr S
We explore the effect of increasing the conjugation length of Results and Discussion
The ΔEST values of 0.26, 0.37, and 0.27 eV were determined from the energy difference between the onset of the prompt fluorescence and phosphorescence spectra in toluene glass at 77 K for DPA-TRZ, TPA-TRZ and TPA-E-TRZ, respectively (Figure 8)
Summary
Activated delayed fluorescence (TADF) emitters have become very popular alternatives to phosphorescent organometallic complexes for organic light-emitting diodes (OLEDs) because this class of materials can likewise recruit both singlet (25%) and triplet (75%) excitons to produce light.[1,2] TADF compounds accomplish this through thermal upconversion of triplet excitons into singlet excitons, a process made possible [a] Dr S. This manuscript is part of a special issue on Organic Donor–Acceptor Systems. This study showcases the balance between the spatial separation of donor and acceptor and the magnitude of the conjugation within the bridging moiety and the effect this has on the relative singlet and triplet excited state energies of the compounds. Both DPATRZ and TPA-E-TRZ are known in the literature.
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