Dibenzothiophene-S,S-dioxide–fluorene co-oligomers. Stable, highly-efficient blue emitters with improved electron affinity

Perepichka, Irene I.; Perepichka, Igor F.; Pålsson, Lars‐Olof

doi:10.1039/b417717g

Cited by 132 publications

(104 citation statements)

References 24 publications

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“…This would explain why there are still no major LEP-based consumer products available in 2005. Note Added in Proof: After this paper was submitted, several important articles describing light-emitting properties of thiophene oligomers [134,135] and copolymers [136±142] were published.…”

Section: Discussionmentioning

confidence: 99%

Light‐Emitting Polythiophenes

et al. 2005

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Polythiophenes are one of the most important classes of conjugated polymers, with a wide range of applications, such as conducting films, electrochromics, and field‐effect transistors, which have been the subject of a number of older and more recent reviews. Much less attention has been paid to the light‐emitting properties of this class of materials, although their unique properties present a number of opportunities unavailable from more popular polymeric light emitters such as polyfluorene or poly(p‐phenylene vinylene). This article reviews achievements to date in applications of thiophene‐based polymers and oligomers as electroluminescent materials. We demonstrate the basic principles of controlling the optical properties of polythiophenes through structural modifications and review the most important light‐emitting materials created from thiophene derivatives. Special attention is paid to consequences of structural variations on the performance of light‐emitting diodes fabricated with these materials.

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Section: Discussionmentioning

confidence: 99%

Light‐Emitting Polythiophenes

et al. 2005

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“…2,7-Dibromo-9,9-dioctylfluorene (F8) and 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester, 4,7-bis-(5-bromo-2-thienyl)-2,1,3-benzothiadizole and 3,7-dibromodibenzothiophene-S,S-dioxide were either synthesized using literature routes [31] or purchased from Sigma-Aldrich and purified by repeated recrystallisations. [31,32] A general method for the preparation of the polymers on a 1 gram scale can be found in the Supporting Information. In similar polymers it has been reported that exceeding 0.05 mol % of TBT results in complete energy transfer to the red unit.…”

Section: Methodsmentioning

confidence: 99%

Exciton Diffusion in Polyfluorene Copolymer Thin Films: Kinetics, Energy Disorder and Thermally Assisted Hopping

Dias

Kamtekar²,

Cazati

et al. 2009

ChemPhysChem

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A series of {(9,9-dioctylfluorene)(0.7-x)-(dibenzothiophene-S,S-dioxide)(0.3)-[4,7-bis(2-thienyl)-2,1,3-benzothiadiazole](x)} (PFS(30)-TBTx), where x represents the minor percentage of the red emitter 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (TBT) randomly incorporated into the copolymer backbone, is investigated in order to follow the energy transfer from PFS(30) to TBT moieties. The emission of the donor poly[(9,9-dioctylfluorene)(0.7)-(dibenzothiophene-S,S-dioxide)(0.3) identified by PFS(30) and peaking at 450 nm, is clearly quenched by the presence of the red TBT chromophore emitting at 612 nm, with an isoemissive point observed when the spectra are collected as a function of temperature. A plot of the ratio between the TBT and PFS(30) emissions as a function of the reciprocal of temperature gives a clear linear trend between 290 and 200 K, with an activation energy of 20 meV and showing a turn over to a non-activated regime below 200 K. Picosecond time-resolved fluorescence decays collected at the PFS(30) and TBT emission wavelengths, show a decay of the PFS(30) emission and a fast build-in, followed by a decay, of the TBT emission, confirming that the population of the TBT excited state occurs during the PFS(30) lifetime (approximately 600 ps). The population of the TBT excited state occurs on a time regime around 150 ps at 290 K, showing an energy barrier of 20 meV that turns over to a non-activated regime below 200 K in clear agreement with the steady-state data. The origin of the activation barrier is attributed to the presence of physical and energetic disorder, affected by fast thermal fluctuations that dynamically change the energy landscape and control the exciton migration through the polymer density of states.

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“…Now it is known that the green shift can be attributed to the formation of fluorenone (Figure 34) defects in the chain Lupton, Craig, and Meijer 2002;Gamerith et al 2004]. This discovery has resulted in the design of new polymers that prevent the formation of the fluorenone defect [McKiernan, Towns, and Holmes 2005;Perepichka et al 2005]. Scientists spent years discussing the cause of the green shift, in part because of the lack of tools capable of analyzing the formation of a small density of defects in an operating device.…”

Section: Background and Motivationmentioning

confidence: 99%

Basic Research Needs for Solid-State Lighting. Report of the Basic Energy Sciences Workshop on Solid-State Lighting, May 22-24, 2006

Phillips¹,

Burrows²,

Davis³

et al. 2006

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Solid-state lighting relies on the conversion of electricity to visible white light using solid materials. By taking advantage of direct electricity-to-light conversion rather than processes in which light is the by-product of another conversion, as with traditional incandescent and fluorescent lighting, it promises unprecedented, near-100% conversion efficiency.Today's solid-state lighting technology, however, requires a fifteen-fold improvement to achieve such conversion efficiencies. The reason is that, to become the standard light source of the 21st century, conversion efficiency must be improved while simultaneously achieving low cost and "high quality" (a human visual experience similar to that provided by sunlight).The front cover is an artistic stylization of a "chromaticity diagram," a common tool that can be used to describe how colors can combine to create the human visual impression of white.White can be produced from as few as two colors, but "highquality" white requires many (e.g., red, yellow, green, and blue) colors. The tessellation overlaid on the chromaticity diagram is suggestive of photonic crystals (nanometer-scale periodic modulations of optical materials that can affect the directionality of light), a frontier area of interdisciplinary science being applied to solid-state lighting.This report outlines basic research needs that could enable solid-state lighting to achieve its potential. The research needs support two overarching challenges: (1) fundamental understanding of light-emitting materials and nanostructures leading to solid-state lighting structures rationally designed from the ground up and (2) control of the competing pathways by which electricity is converted into light not heat so that every injected electron produces a useful photon. Successfully addressing these two challenges promises to enable energy-efficient, cost-effective, high-quality white light that will save energy and benefit the environment. BASIC RESEARCH NEEDS FOR SOLID-STATE LIGHTING EXECUTIVE SUMMARYSince fire was first harnessed, artificial lighting has gradually broadened the horizons of human civilization. Each new advance in lighting technology, from fat-burning lamps to candles to gas lamps to the incandescent lamp, has extended our daily work and leisure further past the boundaries of sunlit times and spaces. The incandescent lamp did this so dramatically after its invention in the 1870s that the light bulb became the very symbol of a "good idea."Today, modern civilization as we know it could not function without artificial lighting; artificial lighting is so seamlessly integrated into our daily lives that we tend not to notice it until the lights go out. Our dependence is even enshrined in daily language: an interruption of the electricity supply is commonly called a "blackout."This ubiquitous resource, however, uses an enormous amount of energy. There is ample room for reducing this energy and environmental cost. The artificial lighting we take for granted is extremely inefficient primarily because a...

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Dibenzothiophene-S,S-dioxide–fluorene co-oligomers. Stable, highly-efficient blue emitters with improved electron affinity

Cited by 132 publications

References 24 publications

Light‐Emitting Polythiophenes

Light‐Emitting Polythiophenes

Exciton Diffusion in Polyfluorene Copolymer Thin Films: Kinetics, Energy Disorder and Thermally Assisted Hopping

Basic Research Needs for Solid-State Lighting. Report of the Basic Energy Sciences Workshop on Solid-State Lighting, May 22-24, 2006

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