RESUMEN
Acceleration of singlet-triplet intersystem crossings (ISC) is instrumental in bolstering triplet exciton harvesting of multi-resonance thermally activated delayed fluorescent (MR-TADF) emitters. This work describes a simple gold(I) coordination strategy to enhance the spin-orbit coupling of green and blue BN(O)-based MR-TADF emitters, which results in a notable increase in rate constants of the spectroscopically observed ISC process to 3×109 â s-1 with nearly unitary ISC quantum yields. Accordingly, the resultant thermally-stable AuI emitters attained large values of delayed fluorescence radiative rate constant up to 1.3×105 /1.7×105 â s-1 in THF/PMMA film while preserving narrowband emissions (FWHM=30-37â nm) and high emission quantum yields (ca. 0.9). The vapor-deposited ultrapure-green OLEDs fabricated with these AuI emitters delivered high luminance of up to 2.53×105 â cd m-2 as well as external quantum efficiencies of up to 30.3 % with roll-offs as low as 0.8 % and long device lifetimes (LT60 ) of 1210â h at 1000â cd m-2 .
RESUMEN
A series of dppnc- and neocuproine-based CuI complexes (dppnc=7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate) are synthesized and the emission color of these CuI complexes can be tuned from green to deep red via rational modification of the neocuproine ligand structure. The molecular structures of the emissive CuI complexes, Cu(dppnc)-G (green emitting), Cu(dppnc)-Y (yellow emitting), and Cu(dppnc)-R (red emitting), are characterized and their electronic structures and related transition properties are elucidated by photo-physical and computational (density functional theory) studies. The calculation results suggest that thermally activated delayed fluorescence (TADF) is the emission mechanism for these CuI complexes. Efficient solution-processed green-, yellow-, and red-emitting OLEDs are fabricated based on the emissive complexes as the dopants. High external quantum efficiency (EQE) of 15.20 % and current efficiency of 48.15â cd A-1 at 1000â cd m-2 are achieved in the green-emitting device with Cu(dppnc)-G. A maximum EQE of 10.17 %, CIE coordinates of (0.61, 0.38) and a maximum electroluminescent peak of 631â nm are achieved in the red device based on Cu(dppnc)-R.
RESUMEN
The synthesis and spectroscopic properties of luminescent tetranuclear zinc(ii) complexes of substituted 7-azaindoles and a series of luminescent copper(i) complexes containing 7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate ligand are described. These complexes are stable towards air and moisture. Thin film samples of the luminescent copper(i) complexes in 2,6-dicarbazolo-1,5-pyridine and zinc(ii) complexes in poly(methyl methacrylate) showed emission quantum yields of up to 0.60 (for Cu-3) and 0.96 (for Zn-1), respectively. Their photophysical properties were examined by ultrafast time-resolved emission spectroscopy, temperature dependent emission lifetime measurements and density functional theory calculations. Monochromic blue and orange solution-processed OLEDs with these Zn(ii) and Cu(i) complexes as light-emitting dopants have been fabricated, respectively. Maximum external quantum efficiency (EQE) of 5.55% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.19) were accomplished with the optimized Zn-1-OLED while these values were, respectively 15.64% and (0.48, 0.51) for the optimized Cu-3-OLED. Solution-processed white OLEDs having maximum EQE of 6.88%, CIE coordinates of (0.42, 0.44), and colour rendering index of 81 were fabricated by using these luminescent Zn(ii) and Cu(i) complexes as blue and orange light-emitting dopant materials, respectively.
RESUMEN
Eight homoleptic metal(III) arylchalcogenolate polymers [M(EPh-p-X)(3)](n) (M = Ru, Cr, and Mo) were characterized by PXRD. Structural solution of [Ru(SPh-p-tBu)(3)](n)1 was achieved by Rietveld refinement of the PXRD data. Pyrolysis of [Ru(SePh)(3)](n)4 produced nanostructured RuSe(2), which selectively catalyzed the reduction of nitro compounds in the presence of other functionalities.