Rational design, synthesis, and characterization of a photocrosslinkable hole-transporting polymer for high performance solution-processed thermally activated delayed fluorescence OLEDs

Lee, Ji Hye; Jeong, Cheol Hun; Godumala, Mallesham; Kim, Chae Yeong; Kim, Hyung Jong; Hwang, Jin Hyo; Kim, Young Kook; Choi, Dae Hyuk; Cho, Min Ju; Choi, Dong Hoon

doi:10.1039/c9tc07107e

Cited by 26 publications

(12 citation statements)

References 35 publications

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“…In the case of cross-linked HTLs, in addition to the reaction of cross-linkable groups during thermal or photocuring, it is also necessary to consider whether the hole transport material (HTM) groups can be degraded or transformed into other structures by thermal treatment or light irradiation. In terms of molecular design, because a cross-linking group is introduced in addition to the basic HTM, synthesis is complicated, and the cross-linking group can act as an obstacle to charge carrier transport. − …”

Section: Introductionmentioning

confidence: 99%

Universal Polymeric Hole Transporting Material for Solution-Processable Green and Blue Thermally Activated Delayed Fluorescence OLEDs

Cho

Kwon

et al. 2023

ACS Appl. Mater. Interfaces

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To obtain high-efficiency solution-processed organic light-emitting diodes (OLEDs), a hole transport material (HTM) capable of solution processing with excellent charge transport properties is required. In this study, a new vinyl polymer (PmCP) containing hole-transporting 1,3-di(9H-carbazol-9-yl)benzene (mCP) in the side chain was successfully synthesized via radical polymerization. PmCP showed good film-forming ability and thermal stability. Moreover, PmCP has a higher triplet energy value and hole mobility than poly(N-vinylcarbazole) (PVK) used as a reference HTM, which can be applied as a hole transport layer (HTL) in thermally activated delayed fluorescence (TADF) OLEDs, providing green and blue emissions. PmCP-based solution-processable TADF-OLEDs containing green- and blue-emitting layers were easily fabricated without damaging the lower HTL while using ethyl acetate as an orthogonal solvent. The corresponding OLEDs possess high external quantum efficiencies of 29.60% and 11.00% for the green- and blue-emitting devices, respectively. They show superior performances compared to PVK-based devices used as a reference. It was confirmed that PmCP as a solution-processable HTM can replace PVK and is universally applicable to both green- and blue-emitting devices.

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Section: Introductionmentioning

confidence: 99%

Universal Polymeric Hole Transporting Material for Solution-Processable Green and Blue Thermally Activated Delayed Fluorescence OLEDs

Cho

Kwon

et al. 2023

ACS Appl. Mater. Interfaces

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“…Solution processing could overcome these limitations, extending to macromolecular charge transport materials − and to large-scale dimensions. Unfortunately, except for conjugated polymers with long-range coplanarity, , solution processing of linear HT polymers bearing pendant charge transport functionalities ,− is incapable of achieving the exquisite molecular ordering of evaporative methods due to the tendency for polymer chains to become kinetically trapped in suboptimal mixed moiety orientations during solvent evaporation, rather leading to unsatisfactory alignment of HT core units, and compromised device performance . Therefore, the development of solution-processable polymeric hole transport materials that enable “face-on” packing of HT functionalities are highly desirable for technically simplified and cost-effective production of large-area OLED displays.…”

Section: Introductionmentioning

confidence: 99%

Topological Design of Highly Anisotropic Aligned Hole Transporting Molecular Bottlebrushes for Solution-Processed OLEDs

Kang¹,

Cho²,

Leonhardt³

et al. 2022

J. Am. Chem. Soc.

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Polyvinyl polymers bearing pendant hole transport functionalities have been extensively explored for solution-processed hole transport layer (HTL) technologies, yet there are only rare examples of high anisotropic packing of the HT moieties of these polymers into substrate-parallel orientations within HTL films. For small molecules, substrate-parallel alignment of HT moieties is a well-established approach to improve overall device performance. To address the longstanding challenge of extension from vapor-deposited small molecules to solution-processable polymer systems, a fundamental chemistry tactic is reported here, involving the positioning of HT side chains within macromolecular frameworks by the construction of HT polymers having bottlebrush topologies. Applying state-of-the-art polymer synthetic techniques, various functional subunits, including triphenylamine (TPA) for hole transport and adhesion to the substrate, and perfluoro alkylsubstituted benzyloxy styrene for migration to the air interface, were organized with exquisite control over the composition and placement throughout the bottlebrush topology. Upon assembling the HT bottlebrush (HTB) polymers into monolayered HTL films on various substrates through spin-casting and thermal annealing, the backbones of HTBs were vertically aligned while the grafts with pendant TPAs were extended parallel to the substrate. The overall design realized high TPA π-stacking along the out-ofplane direction of the substrate in the HTLs, which doubled the efficiency of organic light-emitting diodes compared with linear poly(vinyl triphenylamine)s.

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“…15,16 To address this issue, the cross-linking strategy has been reported to endow the functional layers with good solvent resistance. 17,18 In the preparation of multilayer OLEDs, a cross-linked hole transport layer (HTL) provides a platform to prepare the emitting layer (EML) by the solution method. A series of cross-linkable hole transport materials (HTMs) based on unsaturated acid esters, [19][20][21] oxetane, [22][23][24] benzocyclobutene 25 and vinyl [26][27][28] cross-linking groups have been successfully applied in solution-processed OLEDs.…”

Section: Introductionmentioning

confidence: 99%

Construction of a fully conjugated cross-linked hole-transport film based on ethynyl to enable high mobility for efficient solution-processed OLEDs

et al. 2022

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Rational design, synthesis, and characterization of a photocrosslinkable hole-transporting polymer for high performance solution-processed thermally activated delayed fluorescence OLEDs

Abstract: A new photocrosslinkable PX2Cz was successfully synthesized and used as an excellent hole transport material in green TADF-OLED.

Cited by 26 publications

References 35 publications

Universal Polymeric Hole Transporting Material for Solution-Processable Green and Blue Thermally Activated Delayed Fluorescence OLEDs

Universal Polymeric Hole Transporting Material for Solution-Processable Green and Blue Thermally Activated Delayed Fluorescence OLEDs

Topological Design of Highly Anisotropic Aligned Hole Transporting Molecular Bottlebrushes for Solution-Processed OLEDs

Construction of a fully conjugated cross-linked hole-transport film based on ethynyl to enable high mobility for efficient solution-processed OLEDs

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