Highly Efficient, Simplified, Solution‐Processed Thermally Activated Delayed‐Fluorescence Organic Light‐Emitting Diodes

Kim, Young-Hoon; Wolf, Christoph; Cho, Himchan; Jeong, Seong Mok; Lee, Tae‐Woo

doi:10.1002/adma.201504490

Cited by 132 publications

(99 citation statements)

References 54 publications

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“…21,22 Solution processing has been applied successfully to a few small-molecule TADF OLEDs based on 2,4,5,6-tetra(3,6-di-tert-butylcarbazol-9-yl)-1,3-dicyanobenzene (t4CzIPN) and close analogs. 23,24 Polymeric TADF emitters are particularly suitable for solution processing technologies.…”

Section: Introductionmentioning

confidence: 99%

Pendant Homopolymer and Copolymers as Solution-Processable Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes

Ren

Nobuyasu²,

Dias³

et al. 2016

Macromolecules

145

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This study reports a series of polymers with an insulating backbone and varying ratios of 2-(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide as a pendant TADF unit. Steady-state and time-resolved fluorescence spectroscopic data confirm the efficient TADF properties of the polymers. Styrene, as a co-monomer, is shown to be a good dispersing unit for the TADF groups, by greatly supressing the internal conversion and triplet-triplet annihilation.Increasing the styrene content within the copolymers results in relatively high triplet energy, small energy splitting between the singlet and triplet states (E ST ) and a strong contribution from delayed fluorescence to the overall emission. Green emitting OLED devices employing these polymers as spin-coated emitting layers give high performance, which is dramatically enhanced in the copolymers compared to the homopolymer. Within the series, Copo1 with a regiorandom ratio of 37% TADF units : 63% styrene units displays the best performance with a maximum external quantum efficiency (EQE) of 20.1% and EQE at 100 cd m -2 of 5.3%.2

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Section: Introductionmentioning

confidence: 99%

Pendant Homopolymer and Copolymers as Solution-Processable Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes

Ren

Nobuyasu²,

Dias³

et al. 2016

Macromolecules

145

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“…Conducting polymer TE materials possess the advantages of low κ, good flexibility and low cost in comparison with inorganic materials. [1][2][3][4] Among them, commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS) has received the most attention due to its excellent water processability and high σ ( refs 5-11 ) and is also widely used as an electrode or conductive adhesive material in applications including solar cells, 12,13 organic light-emitting diodes (OLEDs), 14,15 supercapacitors, 16,17 sensors 18,19 and so on. The PSS polyanion enables the formation of aqueous PEDOT:PSS solutions, which benefits both film printing and the synthesis of hybrid materials.…”

Section: Introductionmentioning

confidence: 99%

Micron-thick highly conductive PEDOT films synthesized via self-inhibited polymerization: roles of anions

Shi

Qin

et al. 2017

NPG Asia Mater

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The inhibitor-dependent poly(3,4-ethylenedioxythiophene) (PEDOT) fabrication suffers major problems in the areas of controllability and film thickness. In this work, we found that anions play a key role in both the polymerization and the structure of PEDOT. As a precursor, anions greatly influence the reaction rate and oxidant solubility. In its role as a counter-ion, the anions also affect chain conductance and crystal growth. With these behaviors in mind, a self-inhibited polymerization approach using novel oxidants with appropriate anions was successfully developed to facilitate the fabrication of high quality in situ polymerized PEDOT films and solve the thickness limitation problem. Inhibitor-free heavy oxidative solutions with weakly basic anions enable the spin-coating of thick and homogeneous oxidant layers and also effectively inhibit both the crystallization of the oxidant and H + formation throughout the polymerization process. PEDOT: dodecylbenzenesulfonate (PEDOT:DBSA) exhibits the highest performance among all candidates due to its appropriate anion basicity and low steric effect. An extremely high doping level of 42.9% is achieved, and an electrical conductivity of~1100 S cm − 1 is successfully maintained for film thicknesses between 310 nm and 1.79 μm. In addition, the thermoelectric power factor (RT) for pristine films was improved to 77.2 μW mK − 2 from 69.6 μW mK − 2 by the dedoping treatment. This study provides a new approach for fabricating high performance PEDOT thick films using anion-based design. NPG Asia Materials (2017) 9, e405; doi:10.1038/am.2017.107; published online 14 July 2017 INTRODUCTION Thermoelectric (TE) materials realize direct conversion between heat and electricity, which can be used in refrigeration and power generation. The performance of TE materials is characterized by the ZT value (S 2 σT/κ) or power factor (S 2 σ), where S, σ, T and κ are the Seebeck coefficient, electrical conductivity, absolute temperature and thermal conductivity, respectively. Conducting polymer TE materials possess the advantages of low κ, good flexibility and low cost in comparison with inorganic materials. 1-4 Among them, commercially available PEDOT:polystyrenesulfonate (PEDOT:PSS) has received the most attention due to its excellent water processability and high σ ( refs 5-11 ) and is also widely used as an electrode or conductive adhesive material in applications including solar cells, 12,13 organic light-emitting diodes (OLEDs), 14,15 supercapacitors, 16,17 sensors 18,19 and so on. The PSS polyanion enables the formation of aqueous PEDOT:PSS solutions, which benefits both film printing and the synthesis of hybrid materials. However, such PSS-based processes also experience difficulties with performance optimization. For example, the insulating PSS lamellas remain in the polymer matrix, 20,21 resulting in an amorphous polymer 22 with limited σ and S. 5,9 Compared to PEDOT:PSS, PEDOT doped with smallsized anions (S-PEDOTs), such as tosylate (OTs) or triflate (OTf), have greater potential...

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“…Motivated by this unique stimuli-responsive fluorescence, we attempted to fabricate two-color emissive OLEDs using 1 in the crystalline and amorphous phases as the emission layer (Figure 6a). TheO LEDs have the following layer sequence:i ndium tin oxide (ITO)/poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate):tetrafluoroethyleneperfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer [11] (PEDOT:PSS:PFI, 30 nm)/poly(N-vinylcarbazole) (PVK,…”

Section: Angewandte Chemiementioning

confidence: 99%

Modulating Photo‐ and Electroluminescence in a Stimuli‐Responsive π‐Conjugated Donor–Acceptor Molecular System

et al. 2018

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Functional organic materials that display reversible changes in fluorescence in response to external stimuli are of immense interest owing to their potential applications in sensors, probes, and security links. While earlier studies mainly focused on changes in photoluminescence (PL) color in response to external stimuli, stimuli-responsive electroluminescence (EL) has not yet been explored for color-tunable emitters in organic light-emitting diodes (OLEDs). Here a stimuli-responsive fluorophoric molecular system is reported that is capable of switching its emission color between green and orange in the solid state upon grinding, heating, and exposure to chemical vapor. A mechanistic study combining X-ray diffraction analysis and quantum chemical calculations reveals that the tunable green/orange emissions originate from the fluorophore's alternating excited-state conformers formed in the crystalline and amorphous phases. By taking advantage of this stimuli-responsive fluorescence behavior, two-color emissive OLEDs were produced using the same fluorophore in different solid phases.

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Highly Efficient, Simplified, Solution‐Processed Thermally Activated Delayed‐Fluorescence Organic Light‐Emitting Diodes

Cited by 132 publications

References 54 publications

Pendant Homopolymer and Copolymers as Solution-Processable Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes

Pendant Homopolymer and Copolymers as Solution-Processable Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes

Micron-thick highly conductive PEDOT films synthesized via self-inhibited polymerization: roles of anions

Modulating Photo‐ and Electroluminescence in a Stimuli‐Responsive π‐Conjugated Donor–Acceptor Molecular System

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