Dinuclear Ag(I) Complex Designed for Highly Efficient Thermally Activated Delayed Fluorescence

Abstract

The dinuclear Ag(I) complex has been designed to show thermally activated delayed fluorescence (TADF) of high efficiency. Strongly electron-donating terminal ligands are introduced to destabilize the d orbitals of the Ag ions. Consequently, the orbitals distinctly contribute to the HOMO, whereas the LUMO is localized on the bridging ligand. This ensures charge transfer character of the lowest excited singlet S and triplet T states. Accordingly, a small energy gap ΔE(S-T) is obtained, being essential for TADF behavior. Photophysical investigations show that at ambient temperature the complex exhibits TADF reaching a quantum yield of Φ = 70% with the decay time of only τ = 1.9 μs, manifesting one of the fastest TADF decays observed so far. Such an outstanding TADF efficiency is based on a small value of ΔE(S-T) = 480 cm combined with a large transition rate of k(S → S) = 2.2 × 10 s.

Unusually Fast Phosphorescence from Ir(III) Complexes via Dinuclear Molecular Design

“…As a result, complex 6 is an emitter with an emission rate a few times higher than other Ir(III) phosphors used in OLEDs. 10,14,17,19,21,23,[25][26][27][29][30][31][32] Moreover, by the emission rate, 6 also outcompetes the materials exhibiting thermally activated delayed fluorescence (TADF) [62][63][64][65][66][67][68] which are posed as alternative OLED emitters. 62,[69][70][71][72] The proposed di-nuclear design affords outstanding phosphorescence efficiency and also leaves room for photophysical tuning through modifications of the bridging C^NN^C ligand and N^C^N ligand and also through modifications at the position of the halogen anion.…”

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 ,…”

Oligophosphine-thiocyanate Copper(I) and Silver(I) Complexes and Their Borane Derivatives Showing Delayed Fluorescence

“…20−24 This issue might be resolved by utilizing the electron-rich ancillary ligands, which raise the energy of d orbitals and/or substantially contribute to the HOMO, thus facilitating charge transfer transitions (MLCT or LLCT/XLCT and their mixture) and promoting fast and efficient TADF. 20,21,23…”