Blue Thermally Activated Delayed Fluorescence Polymers with Nonconjugated Backbone and Through-Space Charge Transfer Effect

Shao, Shiyang; Hu, Jun; Wang, Xingdong; Jing, Xiabin; Wang, Fosong

doi:10.1021/jacs.7b10257

Cited by 340 publications

(249 citation statements)

References 26 publications

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“…designed several small‐molecule TADF materials based on triptycence and triarylboron, where charge transfer can happen through space resulting in small Δ E ST . Similarly, Wang et al . first took advantage of this method and prepared TADF vinyl copolymers with through‐space charge transfer effect between the pendant electron donors 9,9‐dimethyl‐10‐phenyl‐acridan ( Ac ) or 9,9‐bis(1,3‐di‐tert‐butylphenyl)‐10‐phenyl‐acridan ( TBAc ) and the acceptor unit 2,4,6‐triphenyl‐1,3,5‐triazine ( TRZ ).…”

Section: Tadf Polymersmentioning

confidence: 99%

“…Four vinyl copolymers P‐Ac50‐TRZ50 , P‐Ac95‐TRZ05 , P‐TBAc50‐TRZ50, and P‐TBAc95‐TRZ05 (Figure ) were synthesized with physically separated pendant units; however, only Ac ‐based polymer exhibited TADF properties with small Δ E ST of 0.019 eV and high PLQYs of up to 60% in film state, since only that structure resulted in sufficient proximate distance to allow through‐space charge transfer. A blue‐emitting device based on polymer P‐Ac95‐TRZ05 exhibited a maximum EQE of 12.1% with small roll‐off of 4.9% (11.5% at 1000 cd m −2 ) …”

Section: Tadf Polymersmentioning

confidence: 99%

See 1 more Smart Citation

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Wei

Voit

2018

Macromol. Rapid Commun.

122

100

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several organic layers like hole injection layer, hole-and electron transport layer, and most importantly, the emissive layers (EML), inserted between the electrodes (Figure 1). Under external voltage, opposite charge carriers of holes and electrons are injected from anode and cathode and finally recombined to produce photons within the EML. [10][11][12] Emitters can largely determine not only the performance but also the processing methods of devices, and therefore they are the key material among all the components of the OLEDs. During the past three decades, the emitter materials have seen a rapid progress, from traditional fluorescent, phosphorescent, and triplet-triplet annihilation (TTA) materials into the era of thermally activated delayed fluorescent (TADF) materials, and from small molecules to polymers. [13] According to spin statistics, singlet and triplet excitons are formed within the EML at the ratio of 1:3, when OLED devices are working under electrical excitation; however, the organic emitters have different capabilities to utilize the exciton to induce photons which results in different efficiencies of OLED devices. The electricity-photon conversion efficiency of OLED can be evaluated by the quantum efficiency (QE), referring to the numeral ratio of photons to the injected electronhole pairs. [14,15] QE can be further subdivided into internal quantum efficiency (IQE) and external quantum efficiency (EQE). The IQE, defined as photon generation within the EML, is directly determined by the emitters, [16] while EQE refers to the numerical ratio of total photons emitting out of the device to the charge pairs injected. Since the photons are generated within and emitted out from the EML, the chemical structure of the emitter and the resulting properties can deeply influence the device efficiency. The traditional fluorescent emitters can only take advantages of singlet excitons for luminescence, with maximal IQE of roughly 25%. Given that out-coupling efficiency is normally 20%, the maximal EQE is only 5%, far below expectation. Phosphorescent OLEDs have the capability to reach 100% IQE, because phosphorescent emitters usually contain heavy atoms like iridium or platinum to harvest both, singlet and triplet excitons for phosphorescence through significant spin-orbit coupling, but the heavy metals usually bring about serious issues of comparable high costs and low long-term stability in OLEDs. [17] TTA fluorescent emitters can only reach a maximum IQE of 62.5% through conversion of two triplet excitons into one singlet exciton, and show mainly blue emission. [18] TADF materials, however, can harvest triplet Organic Light-Emitting Diodes Thermally activated delayed fluorescent (TADF) polymers are promising emitting materials to realize highly efficient, large-scale, and low-cost organic light-emitting diodes (OLEDs) since they exhibit various advantages such as heavy-metal-free structures, 100% theoretical internal quantum efficiency, and ease of large-area fabrication through solution process. At present,...

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Section: Tadf Polymersmentioning

confidence: 99%

Section: Tadf Polymersmentioning

confidence: 99%

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Wei

Voit

2018

Macromol. Rapid Commun.

122

100

View full text Add to dashboard Cite

show abstract

“…Thefirst one is based on the combination of an electron donor (D) and electron acceptor (A). [16][17][18][19][20][21] That is,both Dand Aare carefully aligned at different sites to form aT ADF polymer,s uch as Da nd A simultaneously in the main chain, [16] Dand Asimultaneously in the side-chain, [17,18] or Di nt he main chain and Ai nt he side-chain [19][20][21] etc. Unlike small molecules,i ti sn ot an easy task to realize TADF at am acromolecular level because the relative distance,strength, and location of Dand Aall need to be well controlled to tune through-bond or through-space charge transfer (CT).…”

Section: Introductionmentioning

confidence: 99%

Bridging Small Molecules to Conjugated Polymers: Efficient Thermally Activated Delayed Fluorescence with a Methyl‐Substituted Phenylene Linker

Rao

Liu

et al. 2019

Angew Chem Int Ed

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Based on a “TADF + Linker” strategy (TADF=thermally activated delayed fluorescence), demonstrated here is the successful construction of conjugated polymers that allow highly efficient delayed fluorescence. Small molecular TADF blocks are linked together using a methyl‐substituted phenylene linker to form polymers. With the growing number of methyl groups on the phenylene, the energy level of the local excited triplet state (3LEb) from the delocalized polymer backbone gradually increases, and finally surpasses the charge‐transfer triplet state (3CT). As a result, the diminished delayed fluorescence can be recovered for the tetramethyl phenylene containing polymer, revealing a record‐high external quantum efficiency (EQE) of 23.5 % (68.8 cd A−1, 60.0 lm W−1) and Commission Internationale de l′Eclairage (CIE) coordinates of (0.25, 0.52). Combined with an orange‐red TADF emitter, a bright white electroluminescence is also obtained with a peak EQE of 20.9 % (61.1 cd A−1, 56.4 lm W−1) and CIE coordinates of (0.36, 0.51).

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“…This may be of particular use if the corresponding acrylic monomers required would exhibit markedly different kinetics if polymerized together, resulting in gradient, rather than random, copolymers. Indeed, polymeric materials with donor‐acceptor side‐chains have recently been used as emissive materials for OLEDs and as components of resistive memory …”

Section: Resultsmentioning

confidence: 99%

Synthesis of polymeric organic semiconductors using semifluorinated polymer precursors

Paisley

Tonge

Sauvé

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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The transesterification of 1,1,1,3,3,3‐hexafluoroisopropyl acrylate (HFIPA) homopolymers and block copolymers with methyl acrylate (MA) or n‐butyl acrylate (n‐BuA) were investigated for the efficient synthesis of p‐type and n‐type organic semiconductor acrylates. HFIPA, MA, and n‐BuA are readily prepared in a one‐pot synthesis by Cu(0) reversible deactivation radical polymerization in high yield with low dispersity to give poly(HFIPA)100, PMA100‐b‐poly(HFIPA)x, and PnBuA100‐b‐poly(HFIPA)x (x = 100, 50,25). The transesterification of poly(HFIPA)100 was also studied using 19F NMR spectroscopy. Based on this method, a series of eight homopolymers and three copolymers based on semiconductor motifs commonly found in organic light‐emitting diodes, organic thin‐film transistors, and organic photovoltaics were synthesized with narrow dispersity and conversions up to 99%. These experiments demonstrate that poly(HFIPA) can provide a useful building block in the synthesis of organic electronic materials, providing a simpler route to complex materials which may be challenging to access directly via controlled radical polymerization. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2183–2191

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Blue Thermally Activated Delayed Fluorescence Polymers with Nonconjugated Backbone and Through-Space Charge Transfer Effect

Cited by 340 publications

References 26 publications

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Thermally Activated Delayed Fluorescent Polymers: Structures, Properties, and Applications in OLED Devices

Bridging Small Molecules to Conjugated Polymers: Efficient Thermally Activated Delayed Fluorescence with a Methyl‐Substituted Phenylene Linker

Synthesis of polymeric organic semiconductors using semifluorinated polymer precursors

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