Highly efficient greenish-blue platinum-based phosphorescent organic light-emitting diodes on a high triplet energy platform

Abstract

We have demonstrated high-efficiency greenish-blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a dimesitylboryl-functionalized C^N chelate Pt(II) phosphor, Pt(m-Bptrz)(t-Bu-pytrz-Me). Using a high triplet energy platform and optimized double emissive zone device architecture results in greenish-blue PHOLEDs that exhibit an external quantum efficiency of 24.0% and a power efficiency of 55.8 lm/W. This record high performance is comparable with that of the state-of-the-art Ir-based sky-blue organic light-emitting diodes.

Phosphorescent Pt(II) Emitters for OLEDs: From Triarylboron‐Functionalized Bidentate Complexes to Compounds with Macrocyclic Chelating Ligands

“…Nonetheless, the EL performance of 32 in single‐dopant white OLEDs is very impressive. Subsequently, 32 was incorporated into an EL device with a further optimized structure to improve its performance as a blue emitter . By using host and electron transporting materials with high triplet energies, the new set of EL devices produce bright greenish‐blue phosphorescence with a peak EQE and power efficiency of 24 % and 55.8 lm/W, respectively, which are comparable to the most efficient greenish‐blue phosphorescent OLEDs reported previously…”

Phosphorescent PtAu2 Complexes with Differently Positioned Carbazole–Acetylide Ligands for Solution-Processed Organic Light-Emitting Diodes with External Quantum Efficiencies of over 20%

“…Compounds 1 – 3 (Scheme ) were readily prepared by mixing [Au­(tht) 2 ]­(ClO 4 ), dpmp, and Pt­(PPh 3 ) 2 (CCR) 2 in a 2:2:1 molar ratio with stirring at ambient temperature for 4 h. The products were purified by silica gel column chromatography to afford compounds 1 – 3 in high yields (80–85%). The synthetic procedures of these PtAu 2 cluster complexes are much more convenient and efficient than many mononuclear cyclometalated platinum­(II) complexes accessed by multistep reactions in harsh conditions. − The formation of a doubly μ 3 -dpmp-supported PtAu 2 heteronuclear array involves the substitution of platinum-bound PPh 3 with bridging dpmp, concomitant with the incorporation of two gold­(I) ions. Compounds 1 – 3 are highly soluble in chlorinated solvents such as CH 2 Cl 2 and CHCl 3 .…”

“…Phosphorescent complexes of late-transition-metal elements such as iridium­(III) and platinum­(II) have been flourishingly investigated because of their prosperous applications as emissive materials in organic light-emitting diodes (OLEDs). − Because cyclometalated iridium­(III) and platinum­(II) complexes are charge-neutral species in most cases, high-quality devices can be fabricated through thermal evaporation under high-vacuum conditions. A number of mononuclear cyclometalated platinum­(II) complexes have been designed to achieve high-efficiency OLEDs. − Nevertheless, the synthesis of multidentate chelating ligands and cyclometalated complexes frequently involves multistep synthetic procedures under harsh reaction conditions with relatively low yields. On the other hand, although polynuclear metal cluster complexes exhibit more complicated molecular structures, they are usually accessible in one-step reactions under mild conditions to give high yields.…”

PtII Phosphors with Click-Derived 1,2,3-Triazole-Containing Tridentate Chelates

“…For instance, the notoriously short excited-state lifetimes of bis­(tridentate) Ru II complexes were overcome with the help of 1,2,3-triazolylidene-based ligands, ,− and the employment of 1,2,3-triazole ligands afforded blue-emitting Ir III complexes. − The coordination chemistry of 2,6-bis­(1,2,3-triazol-4-yl)­pyridines was thus widely studied, and Pt II complexes thereof have been reported previously, including small molecule − as well as polymeric ones . Also, the Pt II complexes of related bidentate 2-(1,2,3-triazol-4-yl)­pyridine ligands have been in the focus of interest. − In the case of N ∧ C ∧ N-cyclometalating ligands, namely, 1,3-bis­(1,2,3-triazol-4-yl)­benzenes, the resulting Ru II complexes have been investigated in detail. ,− Recently, bis­(bidentate) Pt II complexes featuring C ∧ N-cyclometalating 1,2,3-triazole-based ligands have also been presented and their potential for the development of efficiently blue-emitting OLEDs was revealed. , …”

“…28,46−50 Recently, bis(bidentate) Pt II complexes featuring C ∧ N-cyclometalating 1,2,3-triazole-based ligands have also been presented and their potential for the development of efficiently blue-emitting OLEDs was revealed. 51,52 In this study, the viability of several tridentate ligand platforms featuring 1,2,3-triazoles or 1,2,3-triazolylidenes regarding the design of Pt II -based emitters is investigated (Figure 1). Besides a series of complexes with N ∧ C ∧ N-type cyclometalating ligands, a Pt II complex bearing the anionic N ∧ N ∧ N-type 1,8-bis(1,2,3-triazol-4-yl)-9H-carbazolide ligand, 53,54 which allows for a six-membered ring chelation, 18,19,55,56 is presented.…”