Design of Conformationally Distorted Donor–Acceptor Dyads Showing Efficient Thermally Activated Delayed Fluorescence

Abstract

A highly potent donor-acceptor biaryl thermally activated delayed fluorescence (TADF) dye is accessible by a concise two-step sequence employing two-fold Ullmann arylation and a sequentially Pd-catalyzed Masuda borylation-Suzuki arylation (MBSA). Photophysical investigations show efficient TADF at ambient temperature due to the sterical hindrance between the donor and acceptor moieties. The photoluminescence quantum yield amounts to Φ = 80% in toluene and 90% in PMMA arising from prompt and delayed fluorescence with decay times of 21 ns and 30 μs, respectively. From an Arrhenius plot, the energy gap Δ E(S - T) between the lowest excited singlet S and triplet T state was determined to be 980 cm (120 meV). A new procedure is proposed that allows us to estimate the intersystem crossing time to ∼10 ns.

A sterically hindered asymmetric D–A–D′ thermally activated delayed fluorescence emitter for highly efficient non-doped organic light-emitting diodes

“…1e). 8 a This is in contrast with previously reported through-space charge transfer TADF emitters in which through-space D–A interaction minimizes the electron-exchange energy and induces a narrow Δ E ST 19. However, the larger overlap integral of frontier orbitals increases the transition dipole moment and thus results in a faster prompt decay.…”

P∩N Bridged Cu(I) Dimers Featuring Both TADF and Phosphorescence. From Overview towards Detailed Case Study of the Excited Singlet and Triplet States

“…While for singlet harvesting, the molecules have to show efficient thermally activated delayed fluorescence (TADF) at ambient temperature. Examples are found among Cu(I), Ag(I), Au(III), W(VI) and Zn(II) complexes [ 7 , 9 , 10 , 11 , 12 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 ] or specifically designed organic molecules [ 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 ,…”

Rational Design of π-Conjugated Tricoordinated Organoboron Derivatives With Thermally Activated Delayed Fluorescent Properties for Application in Organic Light-Emitting Diodes

“…In addition, TADF materials with different donor moieties such as 9,9-dimethyl-9,10-dihydroacridine, 10H-phenoxazine, 5,10-dihydrophenazine, 10H-phenothiazine, 9H-carbazole, 3,6-di-tert-butyl-9H-carbazole, 9,9-diphenyl-9,10dihydroacridine 9H-spiro[4,5]fluorene-9,10-dihydroacridine, 9-(3-(9H-carbazol-9-yl)phenyl)-9H-carbazole, and diphenylamine possess excellent electroluminescence performance (Bezvikonnyi et al, 2019;Hosokai et al, 2019;Jin et al, 2019;Joo et al, 2019;Kim et al, 2019;Sharma et al, 2019;Zhong et al, 2019). Meanwhile, there are many TADF materials with different acceptor moieties such as benzonitrile, triazines, sulfones, benzophenone, quinoxaline, and naphthalimide reported in literature (Li et al, 2016;Nobuyasu et al, 2016;Tsujimoto et al, 2017;Sommer et al, 2018;Wu et al, 2018;Yu et al, 2018). The HOMO/LUMO distribution and energy levels of the typical donor and acceptor moieties have been found in the relevant literature (Im et al, 2017b).…”