Largely Color-Tuning Prompt and Delayed Fluorescence: Dinuclear Cu(I) Halide Complexes with tert-Amines and Phosphines

Abstract

Luminescent copper­(I) halide complexes with bi- and tridentate rigid ligands have gained wide research interests. In this paper, six tetracoordinate dinuclear copper­(I) halide complexes, Cu2X2(ppda)2 [ppda = 2-[2-(dimethylamino)­phenyl­(phenyl)­phosphino]-N,N-dimethylaniline, X = I (1), Br (2), Cl (3)] and Cu2X2(pfda)2 [pfda = 2-[2-(dimethylamino)-4-(trifluoromethyl)­phenyl­(phenyl)­phosphino]-N,N-dimethyl-5-trifluoromethylaniline, X = I (4), Br (5), Cl (6)], were successfully prepared and systematically characterized on their structures and photophysical properties. Complexes 1–5 have a centrosymmetric form with a planar Cu2X2 unit, and complex 6 has a mirror symmetry form with a butterfly-shaped Cu2X2. Solid complexes 1, 4, and 5 emit delayed fluorescence at room temperature, intense blue to greenish yellow (λmax = 443–570 nm) light, and their peak wavelengths are located at 443–570 nm with microsecond lifetimes (τ = 0.4–19.2 μs, ΦPL = 0.05–0.48). Complexes 2, 3, and 6 show prompt fluorescence, very weak yellowish green to yellow (λmax = 534–595 nm) emission with peak wavelengths at 534–595 nm, and lifetimes in nanoseconds (τ = 4.4–9.3 ns, ΦPL < 0.0001). (Metal + halide) to ligand and intraligand charge transitions are the main origin of the emission of the complexes. Solution-processed, complex-4-based nondoped and doped devices emit yellow green light with CIE coordinated at (0.41, 0.51), a maximum EQE up to 0.17%, and luminance reaching 75.52 cd/m2.

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 ,…”

Phase dependence and mechanical and thermal ductility of the luminescence properties of tetranuclear Cu(i) metallacycle assemblies stabilized by ditopic organo-pnictogen (P,As) ligands

“…Such derivatives offer particularly appealing prospects for future developments, not only due to the relatively high abundance and low cost of copper offering a competitive alternative to the well-known phosphorescent compounds based on expensive heavy metal complexes, but also due to the various photophysical properties these Cu( i ) complexes exhibit. 1–46 Indeed, emission covering the full visible light spectrum has been reported for such compounds, combined with a large diversity of radiative relaxation processes, including very efficient Thermally Activated Delayed Fluorescence (TADF) processes. 7,8,13–36 In such complexes presenting TADF properties, spatially well-separated HOMO and LUMO induce a small energy gap between the lowest energy singlet–triplet states.…”

“…1–46 Indeed, emission covering the full visible light spectrum has been reported for such compounds, combined with a large diversity of radiative relaxation processes, including very efficient Thermally Activated Delayed Fluorescence (TADF) processes. 7,8,13–36 In such complexes presenting TADF properties, spatially well-separated HOMO and LUMO induce a small energy gap between the lowest energy singlet–triplet states. This enables a thermal population of the lowest energy excited singlet state (S 1 ) from the lowest energy triplet excited state (T 1 ) via a reverse intersystem crossing (RISC).…”

Structural characterization and luminescence properties of trigonal Cu(i) iodine/bromine complexes comprising cation–π interactions

“…5–7 Previous reports have indicated that Cu( i )-based complexes with different types of coordinated ligands are able to achieve remarkable luminescence characteristics, including room temperature phosphorescence (RTP) and thermally activated delay fluorescence (TADF). 8–12 Such cuprous complexes show great potential for applications in optoelectronic devices and luminescence-based sensors. 13–17 The d 10 configuration of Cu( i ) tends to favor the tetrahedral geometry and extensive studies on Cu( i )-based emitters show that the typical mononuclear four-coordinated Cu( i ) complexes generally exhibit inferior luminescence properties.…”