Enhancement of External Quantum Efficiency of Red Phosphorescent Organic Light‐Emitting Devices with Facially Encumbered and Bulky Pt^II Porphyrin Complexes

Abstract

An enhancement in the external quantum efficiency (QE) of red phosphorescent organic light‐emitting devices (OLEDs) by using facially encumbered and bulky meso‐aryl substituted PtII porphyrin complexes is demonstrated. The maximum external QEs of phosphorescent OLEDs doped with the facially non‐encumbered PtII porphyrin complex 1 [5,15‐bis[4‐(4,4‐dimethyl‐2,6‐dioxacyclohexyl)phenyl]‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrin platinum(II)], the facially encumbered PtII porphyrin complex 2 [5,15‐bis(2,6‐dimethoxyphenyl)‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrinato platinum(II)], the PtII porphyrin complex 3 that bears bulkier 3,5‐di‐tert‐butylphenyl substituents [5,15‐bis(3,5‐di‐t‐butylphenyl)‐2,8,12,18‐tetrahexyl‐3,7,13,17‐tetramethylporphyrin platinum(II)], and the “doubly‐decamethylene‐strapped” PtII porphyrin complex 4 were 1, 4.2, 7.3, and 8.2 %, respectively. The trend of increasing QE values in the order of 1 < 2 < 3 < 4 may be related to facial encumbrance and steric bulkiness of meso‐aryl substituted PtII porphyrin complexes. Especially, in the case of the PtII porphyrin 4, it is considered that the “double straps” play an important role in restricting rotational freedom of the meso‐aryl substituents. The triplet excited‐state lifetimes for PtII porphyrins 1–4 in OLEDs at an injection current density of 0.55 mA cm–2 were 80, 103, 140, and 152 μs, respectively. We believe that the trend of increasing triplet lifetime in going from 1 to 4 is correlated with suppressing non‐radiative decay.

Benefits of using BODIPY–porphyrin dyads for developing deep-red lighting sources

“…To this end, we took advantage of our mature experience in the synthesis of BODIPYporphyrin dyads and their implementation in solar cells [16][17][18][19] to trapping process at the porphyrin, (ii) there is an almost quantitative ET process from the BODIPY to the porphyrin, (iii) there is a lack of phase separation between both components in thin films as they are linked, and (iv) porphyrins are considered as one of the best candidates for developing narrow emission deepred OLEDs. 2,[20][21][22][23][24][25][26][27] On the other hand, LECs are ideal devices to demonstrate our concept, as they are single layer devices based on a single active component, allowing to settle clear relationships between molecular design and device performance. [8][9][10] In addition, this work provides, to the best of our knowledge, the first example of using this family of dyads in lighting schemes, demonstrating the benefits that state from their unique features.…”

Dynamic Rotational Motions of Vaulted Chiral trans‐Bis(salicylaldiminato)palladium(II) Complexes Bearing Rigid or Flexible Carbon Chain Linkers

“…Transition metal complexes vaulted with carbon chains have been extensively studied as functional materials due to their specific three‐dimensional structures based on bridged ligands and coordination planes . A number of such vaulted complexes have been prepared by the reaction of transition metals with tether‐linked ligands, and the correlations between various structures and functions have been studied. This prior research has focused on the association, , , and aggregation properties of these compounds, as well as their optical characteristics, , , , and catalytic activity during organic transformation , …”

Synthesis and Characterization of Novel Red-Light-Emitting Materials with Push-Pull Structure Based on Benzo[1,2,5]thiadiazole Containing Arylamine as an Electron Donor and Cyanide as an Electron Acceptor

“…OLEDs offer a number of advantages over conventional displays, such as faster response time, high efficiency, high color purity, low-voltage driving requirements, and simplicity. [1][2][3][4][5] Despite considerable progress that has been made over recent decades in this area, full-color OLEDs still require improvement in terms of efficiency, purity, durability, manufacturing process, and cost. These factors in turn depend on the evolution of high efficiency OLEDs materials, including RGB emitters.…”