White Electroluminescence by Supramolecular Control of Energy Transfer in Blends of Organic‐Soluble Encapsulated Polyfluorenes

Brovelli, Sergio; Meinardi, Francesco; Winroth, Gustaf; Fenwick, Oliver; Sforazzini, Giuseppe; Frampton, Michael J.; Zalewski, Leszek; Levitt, James A.; Marinello, Francesco; Schiavuta, Piero; Suhling, Klaus; Anderson, Harry L.; Cacialli, Franco

doi:10.1002/adfm.200901764

Cited by 54 publications

(52 citation statements)

References 47 publications

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“…We note that the HATNA* emission in the blend is characterized by a much stronger 0-0 transition (PL 0-0 / PL 0-1 % 1.06) than in the pure HATNA* thin film, consistently with the expected suppression of aggregation as a result of embedding HATNA* in TFB. 36,37 Emission from TFB is nearly completely suppressed, as expected, as a result of efficient energy transfer from TFB to HATNA* (note that although HATNA*'s absorption spectrum is not very strong at low energies, this does extend so as to provide a significant overlap with emission from TFB, see Fig. 1(c)).…”

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confidence: 70%

Virtually pure near-infrared electroluminescence from exciplexes at polyfluorene/hexaazatrinaphthylene interfaces

Tregnago

Fléchon

Choudhary

et al. 2014

Applied Physics Letters

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Electronic processes at the heterojunction between chemically different organic semiconductors are of special significance for devices such as light-emitting diodes (LEDs) and photovoltaic diodes. Here, we report the formation of an exciplex state at the heterojunction of an electron-transporting material, a functionalized hexaazatrinaphthylene, and a hole-transporting material, poly(9,9-dioctylfluorene-alt-N-(4-butylphenyl)diphenylamine) (TFB). The energetics of the exciplex state leads to a spectral shift of ∼1 eV between the exciton and the exciplex peak energies (at 2.58 eV and 1.58 eV, respectively). LEDs incorporating such bulk heterojunctions display complete quenching of the exciton luminescence, and a nearly pure near-infrared electroluminescence arising from the exciplex (at ∼1.52 eV) with >98% of the emission at wavelengths above 700 nm at any operational voltage.

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confidence: 70%

Virtually pure near-infrared electroluminescence from exciplexes at polyfluorene/hexaazatrinaphthylene interfaces

Tregnago

Fléchon

Choudhary

et al. 2014

Applied Physics Letters

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“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Among these scaffolds, DNA-cationic surfactant complexes have emerged as intriguing candidates for optoelectronic applications in recent years because of their unique material properties, including solubility in organic solvents and the ability to form thermally stable, transparent films. 1,2 FRET based fluorescence colour tuning, with fluorophores incorporated into various scaffolds including polymers, biomolecules, micelles, supramolecular assemblies and nanoparticles, is a widely investigated approach for white light generation.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous binding of a cyclophane and classical intercalators to DNA: observation of FRET-mediated white light emission

Sanju

Thurakkal

Neelakandan

et al. 2015

Phys. Chem. Chem. Phys.

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DNA-assisted Förster resonance energy transfer (FRET) between an anthracene-based cyclophane (CP) and mono- and bis-intercalators such as propidium iodide (PI) and ethidium homodimer-1 (EHD), respectively, has been studied using various photophysical and biophysical techniques. The cyclophane and PI exhibited simultaneous binding to DNA at all concentrations studied and showed DNA-assisted FRET from the excimer of cyclophane with a FRET efficiency of ca. 71%. On the other hand, the bis-intercalator EHD, only at lower concentrations (<3 μM), can act as an acceptor for the energy transfer process with a lower efficiency of ca. 44%. At higher concentrations (>15 μM), EHD, on account of its higher binding affinity, displaces cyclophane from the DNA scaffold. Employing the ternary system comprising of the cyclophane, DNA and PI and fine-tuning the concentrations of the components in a molar ratio of 1 : 0.75 : 0.05 (CP : DNA : PI) we have demonstrated white light emission with CIE coordinates (0.35, 0.37).

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“…We recently showed that organic-solvent-soluble, conjugated rotaxanes can be blended with other non-rotaxinated semiconductors to fabricate whiteemitting LEDs. [ 15 ] Intriguingly, suppressed exciton dissociation and polaron formation in rotaxanes can be synergistically exploited with suppression of energy transfer to yield ultrabroadband all-plastic optical amplifi ers by exploitation of the spectrally distinct gain bands of the individual polymers. [ 16 ] More generally, rotaxanes provide unique model systems for the investigation of intermolecular interactions in macromolecular materials.…”

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confidence: 99%

Highly Polarized Emission from Oriented Films Incorporating Water‐Soluble Conjugated Polymers in a Polyvinyl Alcohol Matrix

et al. 2011

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Semiconducting polymers are attracting signifi cant interest due to their tunable optical and electrical properties and processing advantages for the realization of light-emitting devices (e.g., light-emitting diodes (LEDs) [ 1 ] or light-emitting electrochemical cells (LECs) [2][3][4] ), photovoltaics, [ 5 ] fi eld-effect transistors, [ 6 ] and plastic lasers. [ 7 ] Light-emitting applications in particular can benefi t from control or suppression of secondary interactions between the macromolecular strands. Such control is achieved, for example, in conjugated polyrotaxanes: [8][9][10][11] semiconducting polymers are threaded through cyclodextrin (CD) macrocycles, which are then stoppered by bulky steric endgroups on each macromolecule. [ 12 , 13 ] By imposing an increased intermolecular distance between the conjugated cores, cyclodextrins effectively suppress both formation of interchain species, such as π -π stacks and H-aggregates, [ 14 ] and intermolecular energy transfer. We recently showed that organic-solvent-soluble, conjugated rotaxanes can be blended with other non-rotaxinated semiconductors to fabricate whiteemitting LEDs. [ 15 ] Intriguingly, suppressed exciton dissociation and polaron formation in rotaxanes can be synergistically exploited with suppression of energy transfer to yield ultrabroadband all-plastic optical amplifi ers by exploitation of the spectrally distinct gain bands of the individual polymers. [ 16 ] More generally, rotaxanes provide unique model systems for the investigation of intermolecular interactions in macromolecular materials. [ 8 , 9 ] In view of the increased rigidity of the chains upon rotaxination, the question arises as to whether it might be possible to align the molecules to achieve polarized emission. However, the solution processing techniques typically used in polymer electronics produce fi lms with chain orientations that are nearly isotropically distributed within the plane of the fi lm (although essentially horizontal within the plane). It is therefore diffi cult to exploit the intrinsic anisotropy of electronic states of the conjugated strands to achieve polarized emission or absorption when using such techniques. Instead, possible ways for achieving anisotropic optical and electronic properties are through orientation of the macromolecules assisted by mechanical rubbing, [ 17 , 18 ] nanoimprinting, [ 19 , 20 ] photoalignment, [ 21 ] and tensile drawing. [22][23][24] Here, we present the optical properties of highly oriented fi lms obtained by tensile drawing of a stretchable polyvinyl alcohol (PVA) matrix. Aligned fi lms were produced by drop-casting an aqueous solution of PVA (99.5% in weight, M w = 72 000 g mol − 1 ) and poly(4,4'-diphenylene vinylene) (PDV.Li, 0.5% in weight, molecular structure in Figure 1 , M w = 13 400 g mol − 1 for n = 10, where n is the number of repeat units) or the rotaxinated analogue (PDV.Li⊂ β -CD), which are polyelectrolytic derivatives of poly-para -phenylenevinylene where sulfonated side groups balanced by Li + ions ensu...

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White Electroluminescence by Supramolecular Control of Energy Transfer in Blends of Organic‐Soluble Encapsulated Polyfluorenes

Cited by 54 publications

References 47 publications

Virtually pure near-infrared electroluminescence from exciplexes at polyfluorene/hexaazatrinaphthylene interfaces

Virtually pure near-infrared electroluminescence from exciplexes at polyfluorene/hexaazatrinaphthylene interfaces

Simultaneous binding of a cyclophane and classical intercalators to DNA: observation of FRET-mediated white light emission

Highly Polarized Emission from Oriented Films Incorporating Water‐Soluble Conjugated Polymers in a Polyvinyl Alcohol Matrix

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