Concentration-dependent circularly polarized luminescence of chiral cyclometalated platinum(II) complexes for electroluminescence

Highly Phosphorescent Planar Chirality by Bridging Two Square-Planar Platinum(II) Complexes: Chirality Induction and Circularly Polarized Luminescence

“…Ir­(ppy) 3 , ppy = 2-phenylpyridine) that have an intrinsic metal-induced Λ/Δ chirality, − the chirality of square-planar d 8 Pt­(II) complexes is mainly introduced by chiral ligands. − There are limited examples of chiral Pt­(II) complexes with achiral ligands. − However, their CPL has seldom been reported before, mainly due to not only the weak chirality but also the low emission quantum yield (Φ) (Figure S1) of the distorted-square-planar coordination configuration of the Pt­(II) ion. For the same reason, they have not been applied in circularly polarized OLEDs (CP-OLEDs) before, even though CP-OLEDs can emit CPL directly and have extensive applications in 3D displays, optical data storage, and optical spintronics. − Up to now, just a few Pt­(II) complexes with chiral ligands have been used for applications in CP-OLEDs. ,− For example, Jiang et al used chiral binaphthalene (BINA)-based mononuclear Pt­(II) complexes to fabricate solution-processed CP-OLEDs, which have an external quantum efficiency (EQE) and an asymmetry factor ( g EL ) of up to 2.15% and 1.1 × 10 –3 , respectively. Recently, we also demonstrated that the EQE and g EL can be further improved to 3.1% and 3.0 × 10 –3 , respectively, by chiral BINA-bridging binuclear Pt­(II) complexes .…”

Axially Chiral Bis-Cycloplatinated Binaphthalenes and Octahydro-Binaphthalenes for Efficient Circularly Polarized Phosphorescence in Solution-Processed Organic Light-Emitting Diodes

“…In the past two decades, the class of square-planar cyclometalated Pt­(II) complexes has been extensively investigated because of their interesting phosphorescence nature, − but there are only a finite number of chiral Pt­(II) complexes for the applications in CP-OLEDs. − In 2016, Brandt et al used helicene-based Pt­(II) complexes [Figure a, (C^N)*Pt­(O^O), C^N = ( P )/( M )-pyridinyl-helicene, O^O = β-diketones] to construct solution-processed CP-OLEDs, which have a high g EL (+0.22 and −0.38) but a low power efficiency (η P = 0.23 lm W –1 ) . After that Yan et al introduced −F and −CF 3 moieties at a pyridinyl-helicene ligand to increase the volatility and emission intensity for vacuum-evaporated CP-OLEDs (EQE = 18.8%, g EL = 1.6 × 10 –3 ). , Han et al [(N^C^N)­Pt­(≡R)*, N^C^N = 1,3-bis­(2-pyridyl, ≡R = ( R )/( S )-(+)-α-methylbenzylisocyanide, solution-processed CP-OLEDs, luminance efficiency η L = 0.84 cd A –1 , g EL ≈ 10 –4 ], Lee et al [(N^C^N)*Pt­(Cl), N^C^N = ( R )/( S )-1-(2-oxazoline)-3-(2-pyridyl)­phenylate, vacuum-evaporated CP-OLEDs, EQE = 9.7%, g EL = 1.2 × 10 –4 ], and Fu et al [Figure b, (C^N)­Pt­(N^O)*, C^N = 1-(benzo­[b]-thiophen-2-yl)-isoquinoline, N^O = ( R )/( S )-Schiff base ligands; solution-processed CP-OLEDs, EQE = 0.93%, g EL ≈ 10 –3 ] adopted point-chirality-ligand-based Pt­(II) complexes to fabricate CP-OLEDs. Qian et al further utilized a liquid crystal to improve the EL performance of point-chirality-ligand-based Pt­(II) complexes [(N^C)*Pt­(O^O), N^C = ( R )/( S )-2-phenylpyridine derivate, solution-processed CP-OLEDs, EQE = 11.3%, g EL = 0.02] .…”

“…20 After that Yan et al introduced −F and −CF 3 moieties at a pyridinyl-helicene ligand to increase the volatility and emission intensity for vacuum-evaporated CP-OLEDs (EQE = 18.8%, g EL = 1.6 × 10 −3 ). 21,22 Han et al 23 We are increasingly concerned about the preparation, optics, and sensing properties of axially chiral binaphthalenes (BINA). 36−41 Because of a restriction in the intramolecular rotations 27,37 or motions 36 Photophysical Properties.…”

Chiral hybrid manganese(ii) halide clusters with circularly polarized luminescence for X-ray imaging

“…Materials with circularly polarized luminescence (CPL) have attracted widespread attention due to their wide potential applications for 3D displays, optical data storage, photoelectric devices, asymmetric synthesis, and so on. 1–19 In general, the degree of circular polarization is defined by the strength of left and right circularly polarized light ( I L and I R ). 20 In order to effectively evaluate the intrinsic properties of CPL materials, the luminescence dissymmetry factor ( g lum ) is defined as the difference between the strength of I L and I R divided by their average total luminescence strength, namely g lum = 2 × ( I L − I R )/( I L + I R ).…”