TADF for singlet harvesting: next generation OLED materials based on brightly green and blue emitting Cu(I) and Ag(I) compounds

Yersin, Hartmut; Leitl, Markus J.; Czerwieniec, Rafał

doi:10.1117/12.2061010

Cited by 26 publications

(39 citation statements)

References 53 publications

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“…Phosphorescence decay times of the order of milliseconds were found also for other Ag(I) and Cu(I) compounds. 29,34,49,51,74 This long decay displays the spin-forbiddenness of this transition. Obviously, SOC to adequate singlet states is weak.…”

Section: Thermally Activated Delayed Fluorescence and Drastic Increasmentioning

confidence: 96%

Design Strategy for Ag(I)-Based Thermally Activated Delayed Fluorescence Reaching an Efficiency Breakthrough

et al. 2017

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A design strategy is presented for the development of Ag(I)-based materials for thermally activated delayed fluorescence (TADF). Although Ag(I) complexes usually do not show TADF, the designed material, Ag(dbp)(P2-nCB) (with dbp = 2,9-din -butyl-1,10-phenanthroline and P2-nCB = nido-carborane-bis-(diphenylphosphine)), shows a TADF efficiency breakthrough exhibiting an emission decay time of τ(TADF) = 1.4 µs at a quantum yield of ΦPL = 100 %. This is a consequence of three optimized parameters: (i) The strongly electron-donating negatively charged P2-nCB ligand destabilizes the 4dorbitals and leads to low lying charge (CT) states of MLL'CT character, with L and L' being the two different ligands, thus, giving a small energy separation between the lowest singlet S1 and triplet T1 state of ∆E(S1-T1) = 650 cm 1 (80 meV). (ii) The allowedness of the S1→S0 transition is more than one order of magnitude higher than found for other TADF metal complexes, as shown experimentally and by TD-DFT calculations. Both parameters favor short TADF decay time. (iii) The high quantum efficiency is dominantly related to the rigid molecular structure of Ag(dbp)(P2-nCB), resulting from the design strategy of introducing n-butyl substitutions at the 2,9positions of phenanthroline which sterically interact with the phenyl groups of the P2-nCB ligand. In particular, the shortest TADF decay time of τ(TADF) = 1.4 µs at ΦPL = 100 % reported so far suggests the use of this outstanding material for OLEDs.

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Section: Thermally Activated Delayed Fluorescence and Drastic Increasmentioning

confidence: 96%

Design Strategy for Ag(I)-Based Thermally Activated Delayed Fluorescence Reaching an Efficiency Breakthrough

et al. 2017

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“…Therefore, we propose that the introduc-tion of non-negligible contribution of imine (C═N) resulted in its distinct electronic structure, which would further promote the separation of HOMO and LUMO, minimize the singlet-triplet energy gap (E ST ) that activates the RISC process, optimize fluorescence process, and eventually enable highly efficient TADF. In addition, the TADF mechanism of these silver(I) clusters is different from that of reported mononuclear Ag(I) and Cu(I) complexes, which mainly involves transitions of ligand * orbitals dominating S 1 and T 1 states (40,41). As the electronic structure of metal clusters is much more complicated compared to that of small organic molecules, the TADF origin of the silver clusters will be subjected to detailed investigation in the future.…”

Section: Density Functional Theory Calculationsmentioning

confidence: 90%

“…This observation is reminiscent of TADF materials (38)(39)(40)(41), where delayed fluorescence is obtained owing to efficient reverse intersystem crossing (RISC) from the lowest triplet excited state (T 1 ) to the lowest singlet excited state (S 1 ). In the past few years, some strategies have been developed to achieve TADF in low-cost Cu(I) and Ag(I) compounds (38)(39)(40)(41). We tentatively assigned the higher energy emission band (556 nm) of Ag 6 L 6 at RT, which crosses over its excitation spectrum ( Fig.…”

Section: Tadf Contributing To the Bright Photoluminescencementioning

confidence: 97%

Ultrastable atomically precise chiral silver clusters with more than 95% quantum efficiency

et al. 2020

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Monolayer-protected atomically precise silver clusters display low photoluminescence (PL) quantum yield (QY) and susceptibility under ambient conditions, and their chiroptical activities also remain underdeveloped. Here, we report enantiomers of an octahedral Ag6 cluster prepared via one-step synthesis using designed chiral ligands at ambient temperature. These clusters exhibit a highest PLQY (300 K) >95.0% and retain their structural integrity and emission up to 150°C in air. Atomically precise structural determination combined with photophysical and computational analysis revealed that thermally activated delayed fluorescence, observed in silver cluster systems, is responsible for the high PLQY, which combines chirality in excited states to generate strong circularly polarized luminescence. These unprecedented findings open up horizons of investigation of monolayer-protected silver clusters for future luminescence applications.

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“…On account of highly electron-donating ligands, the silver d 10 orbitals begin to contribute to HOMO and near-HOMO, while the π-acceptors facilitate charge transfer from the metal. As a result, (M + L')LCT excited states can be generated, thereby inducing thermally activated delayed fluorescence (TADF) in Ag(I) compounds [22][23][24][25][26][27][36][37][38][39][40][41][42]. In the context of OLED application, it is relevant to note that the (M + L')LCT emission of Ag(I) benefits over that of Cu(I) analogues since the former (i) is shorter in the lifetimes [36,41,42], and (ii) generally appears in the higher energy domain [36,37,39,[43][44][45].…”

Section: Introductionmentioning

confidence: 99%

“…As a result, (M + L')LCT excited states can be generated, thereby inducing thermally activated delayed fluorescence (TADF) in Ag(I) compounds [22][23][24][25][26][27][36][37][38][39][40][41][42]. In the context of OLED application, it is relevant to note that the (M + L')LCT emission of Ag(I) benefits over that of Cu(I) analogues since the former (i) is shorter in the lifetimes [36,41,42], and (ii) generally appears in the higher energy domain [36,37,39,[43][44][45]. On the whole, Ag(I) compounds that emit apparent luminescence at ambient temperature, especially, that of TADF nature, are still rare.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Thermochromic Luminescence of Ag(I) Complexes Based on 4,6-Bis(diphenylphosphino)-Pyrimidine

et al. 2020

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Two Ag(I)-based metal-organic compounds have been synthesized exploiting 4,6-bis(diphenylphosphino)pyrimidine (L). The reaction of this ligand with AgNO3 and AgBF4 in acetonitrile produces dinuclear complex, [Ag2L2(MeCN)2(NO3)2] (1) and 1D coordination polymer, [Ag2L(MeCN)3]n(BF4)2n (2), respectively. In complex 1, µ2-P,P′-bridging coordination pattern of the ligand L is observed, whereas its µ4-P,N,N′,P′-coordination mode appears in 2. Both compounds exhibit pronounced thermochromic luminescence expressed by reversible changing of the emission chromaticity from a yellow at 300 K to an orange at 77 K. At room temperature, the emission lifetimes of 1 and 2 are 15.5 and 9.4 µs, the quantum efficiency being 18 and 56%, respectively. On account of temperature-dependent experimental data, the phenomenon was tentatively ascribed to alteration of the emission nature from thermally activated delayed fluorescence at 300 K to phosphoresce at 77 K.

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TADF for singlet harvesting: next generation OLED materials based on brightly green and blue emitting Cu(I) and Ag(I) compounds

Cited by 26 publications

References 53 publications

Design Strategy for Ag(I)-Based Thermally Activated Delayed Fluorescence Reaching an Efficiency Breakthrough

Design Strategy for Ag(I)-Based Thermally Activated Delayed Fluorescence Reaching an Efficiency Breakthrough

Ultrastable atomically precise chiral silver clusters with more than 95% quantum efficiency

Synthesis and Thermochromic Luminescence of Ag(I) Complexes Based on 4,6-Bis(diphenylphosphino)-Pyrimidine

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