Investigating the molecular orientation of Ir(ppy)3 and Ir(ppy)2(acac) emitter complexes by X-ray diffraction

Murawski, Caroline; Elschner, Chris; Lenk, Simone; Reineke, Sebastian; Gather, Malte C.

doi:10.1016/j.orgel.2017.11.036

Cited by 24 publications

(19 citation statements)

References 29 publications

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“…The influence of the PDM on the orientation of organometallic emitters has previously been a subject of intense discussion. [95,98,166,167] Purely organic fluorescent and TADF emitters are often of low symmetry and composed of donor and acceptor moieties that can lead to significant PDMs. However, this factor has not received much attention thus far in studies regarding the molecular orientation of purely organic emitters.…”

Section: New Directions From Electrostatic Interactionsmentioning

confidence: 99%

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

et al. 2021

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In organic light‐emitting diodes (OLEDs), horizontal orientation of the emissive transition dipole moment (TDM) can improve light outcoupling efficiency by up to 50% relative to random orientation. Therefore, there have been extensive efforts to identify drivers of horizontal orientation. The aspect ratio of the emitter molecule and the glass‐transition temperature (Tg) of the films are currently regarded as particularly important. However, there remains a paucity of systematic studies that establish the extent to which these and other parameters control orientation in the wide range of emitter systems relevant for state‐of‐the‐art OLEDs. Here, recent work on molecular orientation of fluorescent and thermally activated delayed fluorescent emitters in vacuum‐processed OLEDs is reviewed. Additionally, to identify parameters linked to TDM orientation, a meta‐analysis of 203 published emitter systems is conducted and combined with density‐functional theory calculations. Molecular weight (MW) and linearity are identified as key parameters in neat systems. In host–guest systems with low‐MW emitters, orientation is mostly influenced by the host Tg, whereas the length and MW of the emitter become more relevant for systems involving higher‐MW emitters. To close, a perspective of where the field must advance to establish a comprehensive model of molecular orientation is given.

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Section: New Directions From Electrostatic Interactionsmentioning

confidence: 99%

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

et al. 2021

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“…Moreover, random TDM orientation does not necessarily indicate random orientation of the symmetry axis of the molecule. For example, Murawski et al reported that the molecular orientation in the Ir(ppy) 3 film, which has a random TDM orientation [63]. On the other hand, SOP originates from the PDM orientation including its head-to-tail-direction, as it is proportional to ⟨cos θ⟩.…”

Section: Materials Exhibiting Sop and Their Characteristicsmentioning

confidence: 99%

Spontaneous orientation polarization in organic light-emitting diodes

Noguchi

Brütting

Ishii

2019

Jpn. J. Appl. Phys.

109

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Spontaneous orientation polarization (SOP) is inherent in evaporated films of many organic semiconducting molecules with a permanent dipole moment. A significant electric field is formed in the film due to SOP. Consequently, the properties of organic light-emitting diodes (OLEDs) incorporating such films are influenced. The polarization charge appearing at heterointerfaces dominates the charge injection and accumulation properties.Moreover, SOP correlates to device degradation. In this article, we review SOP of organic semiconductor films and its influences on the device properties of OLEDs.

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“…Nevertheless, the water-insolubility of Ir(ppy) 2 (acac) restricted its application in biosensing. Moreover, Ir(ppy) 2 (acac) can self-assemble into amorphous aggregates with different sizes in different water fractions . Therefore, it is highly demanded to figure out how to control the formation of iridium self-assemblies with improved water solubility and dispersity for aqueous immunoassays.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, Ir(ppy) 2 (acac) can self-assemble into amorphous aggregates with different sizes in different water fractions. 13 Therefore, it is highly demanded to figure out how to control the formation of iridium self-assemblies with improved water solubility and dispersity for aqueous immunoassays. Apoferritin (apoHSF) is a quasispherical protein nanocage of ferritin (from horse spleen) after removing the inside iron atoms.…”

Section: ■ Introductionmentioning

confidence: 99%

PEGylation Improved Electrochemiluminescence Supramolecular Assembly of Iridium(III) Complexes in Apoferritin for Immunoassays Using 2D/2D MXene/TiO₂ Hybrids as Signal Amplifiers

Yang

et al. 2021

Anal. Chem.

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Dynamic self-assembly of iridium complexes in watersoluble nanocontainers is an important bottom-up process for fabricating electrochemiluminescence (ECL) bioprobes. PEGylated apoferritin (PEG-apoHSF) as the host offers a confined space to alter and modify the self-assembly of trans-bis(2-phenylpyridine)-(acetylacetonate)iridium(III) [Ir(ppy) 2 (acac)] based on a pH-dependent depolymerization/reassembly pathway, allowing the formation of ECL-active iridium cores in PEG-apoHSF cavities (Ir@PEG-apoHSF). With an improved encapsulation ratio in PEG-apoHSF, the coreactant ECL behavior of the fabricated Ir@PEG-apoHSF nanodots with tri-npropylamine (TPrA) was further demonstrated, exhibiting maximum ECL emission at 530 nm that was theoretically dominated by the band gap transition. The application of Ir@PEG-apoHSF as a bioprobe in a "signal-on" ECL immunosensing system was developed based on electroactive Ti 3 C 2 T x MXenes/TiO 2 nanosheet (Ti 3 C 2 T x /TiO 2 ) hybrids. Combining with the efficiently catalyzed electro-oxidation of TPrA and Ir(ppy) 2 (acac) by Ti 3 C 2 T x /TiO 2 hybrids, the developed immunosensor showed dramatically amplified ECL responses toward the target analyte of neuron-specific enolase (NSE). Under experimental conditions, linear quantification of NSE from 100 fg/mL to 50 ng/mL was well established by this assay, achieving a limit of detection (LOD) of 35 fg/mL. The results showcased the capability of PEGylated apoHSF to host and stabilize water-insoluble iridium complexes as ECL emitters for aqueous biosensing and immunoassays.

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Investigating the molecular orientation of Ir(ppy)3 and Ir(ppy)2(acac) emitter complexes by X-ray diffraction

Abstract: Investigating the molecular orientation of Ir(ppy) 3 and Ir(ppy) 2 (acac) emitter complexes by X-ray diffraction, Organic Electronics (2017),

Cited by 24 publications

References 29 publications

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

Spontaneous orientation polarization in organic light-emitting diodes

PEGylation Improved Electrochemiluminescence Supramolecular Assembly of Iridium(III) Complexes in Apoferritin for Immunoassays Using 2D/2D MXene/TiO₂ Hybrids as Signal Amplifiers

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Investigating the molecular orientation of Ir(ppy)3 and Ir(ppy)2(acac) emitter complexes by X-ray diffraction

Abstract: Investigating the molecular orientation of Ir(ppy) 3 and Ir(ppy) 2 (acac) emitter complexes by X-ray diffraction, Organic Electronics (2017),

Cited by 24 publications

References 29 publications

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

Spontaneous orientation polarization in organic light-emitting diodes

PEGylation Improved Electrochemiluminescence Supramolecular Assembly of Iridium(III) Complexes in Apoferritin for Immunoassays Using 2D/2D MXene/TiO2 Hybrids as Signal Amplifiers

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PEGylation Improved Electrochemiluminescence Supramolecular Assembly of Iridium(III) Complexes in Apoferritin for Immunoassays Using 2D/2D MXene/TiO₂ Hybrids as Signal Amplifiers