Hole-transporting side-chain polystyrenes based on TCTA with tuned glass transition and optimized electronic properties

Limberg, Felix R. P.; Miasojedovas, Arūnas; Pingel, Patrick; Reisbeck, Felix; Janietz, Silvia; Monkman, Andrew P.; Krüger, Hartmut

doi:10.1039/c5ra12963j

Cited by 9 publications

(11 citation statements)

References 24 publications

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“…The synthesis of the donor–spacer (D) – (S) component of the dye is shown in Scheme . Donor 2b is synthesized by refluxing 1 in N , N -dimethylformamide (DMF) with 1-fluoro-4-iodobenzene and CsCO 3 . Donor 2a is commercially available and used without further purification.…”

Section: Resultsmentioning

confidence: 99%

“…13 C NMR gave signals at 1.2 (grease) ppm . Tetrakis(triphenylphosphine)palladium(0), tributyl(3-methylthiophene-2-yl)stannane ( 3 ), 4,7-dibromobenzo[ c ][1,2,5]thiadiazole ( 10 ), 3,6-dibromo-9 H -carbazole ( 1 ), 5-(7-bromobenzo[ c ][1,2,5]thiadiazol-4-yl)thiophene-2-carbaldehyde ( 8 ), 3,3′-diiodo-2,2′-dimethoxy-1,1′-binaphthalene ( 13( S )a ), and 2,2′-dimethoxy-1,1′-binaphthalene ( 12( S ) ) were synthesized according to the reported literature. 3-Iodo-2,2′-dimethoxy-1,1′-binaphthalene ( 13( S )b ) was synthesized in a modified synthetic procedure of the reported literature in improved yields …”

Section: Methodsmentioning

confidence: 99%

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Synthesis of Chiral Donor–Acceptor Dyes to Study Electron Transfer Across a Chiral Bridge

2020

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Chiral organic dyes comprising a donor (D), spacer (S), primary acceptor (A1), chiral bridge (B(S)), and final acceptor/radical (A2)/(R) have been synthesized and fully characterized. The goal behind this synthetic pursuit is to study whether the chiral dyes can impart a chiral-induced spin selectivity (CISS) spin-filtering effect during an intramolecular charge-transfer (CT) process. Additionally, appending a stable free radical (SFR) allows the study of how an unpaired spin influences the CT state. The dyes are reported to vary in the position of (A1) with respect to (B(S)). Two series of dyes have been synthesized: one series incorporates (A1) before (B(S)) and the second series places (A1) after (B(S)). In the case where (A1) is before (B(S)), CT is observed between (D) and (A1), but the CT state does not transverse over the chiral bridge to the final (A2)/(R) termini. However, when (A1) is placed after (B(S)), CT over or through the bridge occurs. Computations support the experimental data, which indicate that it is necessary to have (A1) located after (B(S)) to achieve CT over the chiral bridge. Hence, the second set of dyes are optimal candidates to explore intramolecular CISS.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Synthesis of Chiral Donor–Acceptor Dyes to Study Electron Transfer Across a Chiral Bridge

2020

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“…OLEDs comprising poly‐TCTA showed very good properties and lifetimes, but its T g = 245 °C is too high for crosslinking applications. In a previous study, poly‐TCTA was modified toward crosslinkability with poly(4‐(3,6‐dibutoxy‐ 9H ‐carbazol‐9‐yl)‐ N ‐(4‐(3,6‐dibutoxy‐ 9H ‐carbazol‐9‐yl)phenyl)‐ N ‐(4‐vinylphenyl)aniline) ( poly ‐ 3,6‐(BuO) 4 ‐TCTA ) ( 3 ) exhibiting a T g = 150 °C. The butoxy‐groups increase the highest occupied molecular orbital (HOMO) level to E HOMO = −5.25 eV (for comparison, poly‐TCTA: E HOMO = −5.62 eV), while maintaining the molecule's electron blocking ability with a high lowest unoccupied molecular orbital (LUMO) level E LUMO = −2.17 eV and a high triplet energy E T = 2.81 eV.…”

Section: Resultsmentioning

confidence: 99%

1‐Ethynyl Ethers as Efficient Thermal Crosslinking System for Hole Transport Materials in OLEDs

Limberg

Schneider

Höfle

et al. 2016

Adv Funct Materials

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A new crosslinking concept based on a thermally activated one‐component building block with thermally initiated crosslinkable ynol ether is introduced. For polystyrene matrices with glass transition temperatures below the reaction temperature, full conversion is reached within 30 min at 160 °C without employing any catalysts or co‐reactants. The ynol ethers are chemically inert toward a variety of reaction conditions (e.g., radicals and strong bases) and consequently applicable to a wide range of materials for organic electronics. The crosslinkable solid compounds are bench‐stable over more than a year. The broad applicability is demonstrated with a liquid model compound and a specifically designed crosslinking monomer introduced successfully as building block into polystyrenes with pending hole transporting groups. A detailed study of crosslinking kinetics by infrared measurements as well as an alternative method of crosslinker content determination utilizing differential scanning calorimetry is presented. The crosslinkable polymer and the corresponding noncrosslinkable molecule tris(4‐(3,6‐dibutoxy‐9H‐carbazol‐9‐yl)phenyl)amine (BuO6TCTA) are synthesized and investigated as hole transport layers (HTLs) in phosphorescent organic light emitting diodes (OLEDs). OLEDs with crosslinked and noncrosslinked HTLs show efficiencies around 80 cd A−1, indicating negligible influence of the crosslinking process on the device performance while yielding better HTL durability against solvent rinsing.

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“…As a first step, we presented cross-linkable side-chain polymers for the HTL in solution-processed multilayer OLED structures. 14 More recently, we incorporated ambipolar side-chain moieties into polystyrenes and applied them as the host material in the emission layer. 15 The device architecture was based on our cross-linked HTL.…”

Section: ■ Introductionmentioning

confidence: 99%

“…15 The device architecture was based on our cross-linked HTL. 14 A natural next step in device fabrication (i.e., deposition of the ETL) via solution-processing would be to cross-link the emission layer components; however, this approach requires laborious efforts because the emission layer normally consists of at least two materials (host and emitter) and the modification of established emitter materials is often not feasible. Therefore, there are only a few reported examples of efficient OLEDs with a cross-linked emission layer.…”

Section: ■ Introductionmentioning

confidence: 99%

Orthogonal Solution-Processable Electron Transport Layers Based on Phenylpyridine Side-Chain Polystyrenes

Lorente

Pingel

Miasojedovas

et al. 2017

ACS Appl. Mater. Interfaces

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This article reports the synthesis and characterization of a series of polystyrenes containing phenylpyridine moieties as side chains. Methanol solubility of these polymers is induced if the relative pyridine content of the overall aromatic units of the side chains is larger than 0.5. This allows for orthogonal processing of multilayered organic light emitting diode (OLED) stacks fabricated from solutions. The polymers show high thermal stability due to their glass-transition temperatures ranging from 136 up to 247 °C. High triplet energies of up to 2.8 eV are obtained by combination of the side-chain aromatic rings in the meta position. The use of the methanol soluble side-chain polymers as an electron transport layer (ETL) is demonstrated in an orthogonally processed three-layer green-emitting OLED stack. When depositing the ETL from methanol, redissolution of the underlying emission layer does not occur.

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Hole-transporting side-chain polystyrenes based on TCTA with tuned glass transition and optimized electronic properties

Abstract: The development of crosslinkable materials for the fabrication of solution processable OLEDs presents challenges, especially regarding the adjustment of the glass transition (T g ), which has a significant influence on crosslinking kinetics and device life-time.

Cited by 9 publications

References 24 publications

Synthesis of Chiral Donor–Acceptor Dyes to Study Electron Transfer Across a Chiral Bridge

Synthesis of Chiral Donor–Acceptor Dyes to Study Electron Transfer Across a Chiral Bridge

1‐Ethynyl Ethers as Efficient Thermal Crosslinking System for Hole Transport Materials in OLEDs

Orthogonal Solution-Processable Electron Transport Layers Based on Phenylpyridine Side-Chain Polystyrenes

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