Light‐Induced Solubility Modulation of Polyfluorene To Enhance the Performance of OLEDs

Schelkle, Korwin M.; Bender, Markus; Jeltsch, Krischan F.; Buckup, Tiago; Müllen, Kläus; Hamburger, Manuel; Bunz, Uwe H. F.

doi:10.1002/anie.201505141

Cited by 35 publications

(32 citation statements)

References 35 publications

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“…As reported, only a limited number of blue polymers exhibited excellent performance. As one of the promising blue emitters, polyfluorenes (PFs) are attractive because of its high photoluminescence quantum efficiency (PLQY), good thermal and electrochemical stability and facile functionalization at the C‐9 position of the fluorene unit . However, due to fluorenone defect formation and the poor electron transport ability, the color purity of PFs is unsatisfactory, and the efficiency of the devices based on such emitters are still low, which limited its extensive application.…”

Section: Introductionmentioning

confidence: 99%

Deep‐blue light‐emitting polyfluorenes with asymmetrical naphthylthio‐fluorene as Chromophores

Wang

et al. 2018

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

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A novel blue polycyclic aromatic compound 2,8‐dibromo‐14,14‐dioctyl‐14H‐benzo[b]benzo [5,6] fluoreno[1,2‐d]thiophene 9,9‐dioxide (Br2NFSO) is designed and synthesized through multistep synthesis, and its structure is confirmed by nuclear magnetic resonance. Based on synthesized polycyclic aromatic compound Br2NFSO, a series of twisted blue light‐emitting polyfluorenes derivatives (PNFSOs) are prepared by one‐pot Suzuki polycondensation. Based on the twisted polymer molecular structure resulted from the asymmetric links of 14,14‐dioctyl‐14H‐benzo[b]benzo[5,6]fluoreno[1,2‐d]thiophene 9,9‐dioxide (NFSO) unit in copolymers and better electron transport ability of NFSO than those of the electron‐deficient dibenzothiophene‐S,S‐dioxide counterpart, the resulting polymers exhibit excellent electroluminescent spectra stability in the current densities from 100 to 800 mA cm−2, and show blue‐shifted and narrowed electroluminescent spectra with the Commission Internationale de L′Eclairage (CIE) of (0.16, 0.07) for PNFSO5, compared to poly(9,9‐dioctylfluorene) (PFO) with the CIE of (0.18, 0.18). Moreover, the superior device performance is achieved based on PNFSO5 with the maximum luminous efficiency (LEmax) of 1.96 cd A−1, compared with the LEmax of 0.49 cd A−1 for PFO. The results indicate that the twisted polycyclic aromatic structure design strategy has a great potential to tuning blue emission spectrum and improving EL efficiency of blue light‐emitting polyfluorenes. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 171–182

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Section: Introductionmentioning

confidence: 99%

Deep‐blue light‐emitting polyfluorenes with asymmetrical naphthylthio‐fluorene as Chromophores

Wang

et al. 2018

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

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“…The intense blue emission and high photoluminescence quantum yields of polyfluorenes (PFs) have led to their widespread deployment as active components in polymer light-emitting diodes [1][2][3][4][5] and sensors and diagnostics. [6][7][8][9][10][11] Conjugated polymers derive their unique optoelectronic properties from the delocalized electronic structure of the polymer backbone, which is intrinsically linked to the conformation of the polymer chains.…”

Section: Introductionmentioning

confidence: 99%

Targeted β-Phase Formation in Poly(fluorene)–Ureasil Grafted Organic–Inorganic Hybrids

et al. 2017

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The development of synthetic strategies to control the molecular organization (and inherently linked optoelectronic properties) of poly(fluorene)s is critical for the development of efficient light-emitting devices. Here, we report a facile route using sol-gel chemistry to promote the formation of the β-phase through the covalent-grafting of poly[(9,9dioctylfluorene)-co-(9,9-bis(8-hydroxyoctyl)fluorene)] (PFO-OH) to poly(oxyalkylene)/siloxane hybrids known as ureasils, due to the urea linkages binding the organic and inorganic components. Although grafting occurs within the siliceous domains, the degree of branching of the organic backbone determines the packing of the PFO-OH chains within the ureasil framework. Moreover, photoluminescence studies indicate that physical 2 confinement also plays a key role in promoting the evolution of the β-phase of PFO-OH as the sol-gel transition proceeds. Spectroscopic and structural analyses reveal that di-branched ureasils promote linear packing of the PFO-OH chains, whilst tri-branched ureasils exhibit a more open, distorted structure, that restricts the packing efficacy and reduces the number of covalent anchorages. These results indicate that the organic-inorganic hybrid structure induces distinct levels of β-phase formation and that covalent-grafting is a versatile approach to design novel poly(fluorene) hybrid materials with tailored optical properties. T-403, d-UPTES, t-UPTES, DU-PF-x and TU-PF-x, PXRD, 13 C and 29 Si MAS-NMR, supporting PL measurements (emission and excitation spectra, Gaussian deconvolution, PL quantum yields). The following files are available free of charge. Meazzinietal_2017_ESI.pdf AUTHOR INFORMATION

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“…Keeping in mind the enormous importance of photolithography to electronics, it is not surprising that the concept of directly photopatternable organic electronic materials have found significant interest. [14][15][16][17][18][19][20][21][22][23][24][25][26] Our approach to photopatternable conjugated polymers rests on the concept that the vast majority of conjugated polymers require flexible side chains for solubility, and that their removal should render materials insoluble. In addition, solubilizing side chains causes several problems for organic electronic materials: i) they take up large fractions of active layer volume, ii) labile bonds in these chains are primary sources of photochemical decomposition, [27][28][29] iii) as they render most conjugated polymers soluble in the same solvents, fabricating stratified, multilayer devices using only solvent-based techniques can restrict the materials used to those that are orthogonally soluble.…”

Section: Photocleavable Side Chainsmentioning

confidence: 99%

Stimuli-responsive side chains for new function from conjugated materials

Thomas

Pawle

Smith

2016

Journal of Photochemistry and Photobiology A: Chemistry

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This article describes several projects in our laboratory relating to stimuliresponsive conjugated materials using functional side chain moieties. Although side chain engineering has become increasingly important in controlling the packing of conjugated materials, these groups have typically been reserved for imparting solubility to otherwise insoluble materials. By incorporating solubilizing side chains through photocleavable nitrobenzyl linkers, new conjugated polymers behave as negative photoresists upon exposure to ultraviolet light with minimal photobleaching. Our approach enables photopatterning and solution-based fabrication of multilayer conjugated polymer films without the use of orthogonally soluble materials. Work to understand the electronic effects of the aromatic side chain substituents in these materials led to the subsequent discovery of aromatic interactions between side chains and main chains that control the conformations of solid-state phenylene-ethynylene oligomers, including highly twisted conjugated backbones. Such materials, when appropriately substituted, display reversible piezochromic and mechanofluorochromic behavior.

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Light‐Induced Solubility Modulation of Polyfluorene To Enhance the Performance of OLEDs

Cited by 35 publications

References 35 publications

Deep‐blue light‐emitting polyfluorenes with asymmetrical naphthylthio‐fluorene as Chromophores

Deep‐blue light‐emitting polyfluorenes with asymmetrical naphthylthio‐fluorene as Chromophores

Targeted β-Phase Formation in Poly(fluorene)–Ureasil Grafted Organic–Inorganic Hybrids

Stimuli-responsive side chains for new function from conjugated materials

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