A New Entry to Purely Organic Thermally Activated Delayed Fluorescence Emitters Based on Pyrido[2,3‐b]pyrazine‐Dihydrophenazasilines Donor‐Acceptor Dyad

Abstract

A new family of thermally activated delayed fluorescence (TADF) emitters based on a twisted donoracceptor (DÀ A) dyad scaffold comprising of dihydrophenazasiline (D) and pyrido[2,3-b]pyrazine (A) has been developed, and their properties have been investigated. Time-resolved spectroscopic analysis in matrices revealed the detailed photophysical properties of the DÀ A compounds. These DÀ A compounds serve as the emitter for organic light-emitting diodes (OLEDs), showing a moderate external quantum efficiency (EQE) up to 9% in CBP matrix. Furthermore, theoretical calculations uncovered the excited states nature of the developed TADF emitters.

Thermally Activated Delayed Fluorescent Solvent‐free Organic Liquid Hybrids for Tunable Emission Applications

“…As shown in Figure 1c, a similar spectral feature was noticed for 1 in the steady‐state emissions at 298 and 77 K. The exciting fact was the presence of a peak located at 484 nm when 0.1 ms detector delay was applied in the phosphorescence spectral measurement (Figure 1b). The similarity and significant overlap between the fluorescence and phosphorescence spectra confirm the minimal singlet‐triplet energy gap (Δ E ST ) (Figure S3) [40–41] . It validates the support of molecular design and liquid feature in imparting TADF for 1 with a lifetime ( τ TADF ) of 10 μs (Figure S4 and Table S3, 4).…”

“…Hence, technologically advanced lighting and display applications demand newer emitters with improved processability and luminescence features [23–26] . In this direction, solvent‐free organic liquids (SOLs) have been keenly investigated as a new soft material to undertake the above‐mentioned challenges to a certain extent [27,28–48] . The recent examples of emissive SOLs project them as a possible alternate soft material to address the balance between efficiency and processability.…”

Contributing to Biochemistry and Optoelectronics: Pyrrolo[1′,2′:2,3]imidazo[1,5-a]indoles and Cyclohepta[4,5]pyrrolo[1,2-c]pyrrolo[1,2-a]imidazoles via [3+2] Annulation of Acylethynylcycloalka[b]pyrroles with Δ1-Pyrrolines

“…On the other hand, it is known that in solid media organic molecules with a small singlet–triplet (S-T) gap and a donor–acceptor (D-A) character can exhibit thermally activated delayed fluorescence (TADF) [ 29 , 30 ]. The mechanism is based on the thermal upconversion of the triplet excitons into singlets via the reverse intersystem crossing.…”

A Review on the Synthesis of Fluorescent Five- and Six-Membered Ring Azaheterocycles

“…In order to develop a new family of thermally activated delayed fluorescence (TADF) emitters, utilizing the donor-acceptor scaffold, Goya et al [ 46 ] focused on the use of the electron-deficient azaaromatic scaffold in place of the usual dibenzo[ a , j ]phenazine (DBPHZ) unit. Organic compounds that can display TDAF are very intense studied as emitters for efficient OLEDs, since they can achieve theoretically 100% internal quantum efficiency (IQE) by harvesting electrically generated triplet excitation and convert into the emissive singlet excitations through reverse intersystem crossing (rISC).…”