Influence of oligothiophene layer on PVK-based blue light-emitting diode

Lim, Sang Hoon; Shin, Dong-Myung

doi:10.1016/s0379-6779(00)00371-4

Cited by 14 publications

(14 citation statements)

References 8 publications

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“…26 In compound 6 the HOMO is delocalized over all fragments of the molecule, except for the crown ethers, whereas the H (5,6,8,9) H (3,11) LUMO is mainly localized on the thiophene fragments. Therefore, it can be considered that the long wavelength absorption band in the spectrum of compound 6 is caused by the intramolecular charge transfer from the donor to acceptor part of the molecule (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…5 Specific functionalization of conducting thiophene polymers is important for the development of chemical sensors with high sensitivity and stability. 6-8 In particu lar, crown ethers with ionophoric properties and covalent ly linked with polythiophenes undergo complex formation reactions with metal ions to change considerably the opti cal and electrochemical characteristics of the whole sys tem, thus providing these compounds with the properties of efficient sensors.…”

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confidence: 99%

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Novel crown-containing 3-styryl derivatives of oligothiophenes: synthesis, structure, and optical and electrochemical characteristics

et al. 2009

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A method for the synthesis of the 3 substituted polythiophene derivatives including two crown containing styryl fragments was proposed. The optical properties of the obtained com pounds are characterized by the presence of intense absorption and fluorescence bands. The oxidation to the thiophene derivatives involves the crown containing styryl fragment and should be sensitive to the presence of the metal cation in the crown ether cavity.The intensive development of chemistry of poly thiophenes is associated with their electronic and optical properties, which makes it possible to use these compounds for the creation of efficient field transistors, 1,2 organic la ser diodes, 3 cells of solar batteries, 4 and electrolumines cence devices. 5 Specific functionalization of conducting thiophene polymers is important for the development of chemical sensors with high sensitivity and stability. 6-8 In particu lar, crown ethers with ionophoric properties and covalent ly linked with polythiophenes undergo complex formation reactions with metal ions to change considerably the opti cal and electrochemical characteristics of the whole sys tem, thus providing these compounds with the properties of efficient sensors.Crown containing polythiophenes were first obtained 9 in 1993, when the starting monomers represented bis thiophenes linked at positions 3,3´ by the polyether chain. Crown annelated polythiophenes were studied, 10-13 and aza and oxathiacrown ethers containing three thiophene fragments were obtained. 14,15 Oligothiophenes linked with the crown ether fragment through the spacer were synthe sized. 16-19 The influence of complex formation of the thiophene containing crown ethers on their optical and electrochemical characteristics was described only in sev eral works 9,10,12,13,15 for several cations (Na, K, Ba, Sr, Pb) and, therefore, studies in this direction are significant for the development of new efficient receptors.We have earlier 20,21 reported the synthesis and proper ties of new crown containing bis(2 styryl)polythiophenes. The compounds demonstrated the properties of optical and electrochemical sensors for alkaline earth metal cat ions. A distinctive feature of the compounds is their ability to intermolecular sandwich organization in the presence of cations with larger sizes and in monolayers. The forma tion of intermolecular aggregates considerably decreased the intensity of the absorption and fluorescence spectra of the molecules and increased their electrochemical activi ty. In the present work, we developed methods for the synthesis of earlier unknown crown containing 3 styryl n = 0, R = H; n = 1,2, R =

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Novel crown-containing 3-styryl derivatives of oligothiophenes: synthesis, structure, and optical and electrochemical characteristics

et al. 2009

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“…Although better performing blue (singlet) emitting conjugated polymers exist for the moment, PVK has energy levels excellently situated to host a blue triplet emitter. Furthermore a large amount of experimental information exists on this commercially available polymer and its photophysics [15][16][17][18][19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Blue light-emitting-diodes from poly (N-vinylcarbazole) doped with colloidal quantum dots encapsulated with carbazole terminated ligand: spectroscopic studies and devices

et al. 2012

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Blue emitting CdSe/ZnS quantum dots (QDs) were encapsulated with the ligand 11-(N-carbazolyl) undecanoic acid (C11). Steady-state photoluminescence (PL) experiments show an enhancement of the QD emission upon the excitation of the carbazole ligand in solution compared to the situation where a solution with the same concentration of QDs capped with oleic acid (OA) were excited at the same wavelength. This suggests energy transfer from the carbazole moiety to the QD cores. When incorporating the QDs in a poly (N-vinylcarbazole) (PVK) matrix, a significant enhancement of the QD emission upon the excitation of PVK was also observed indicating an efficient energy transfer from PVK to the QDs in the case of C11 capped ligands. Confocal microscopy images of the doped PVK films show clearly better miscibility of PVK and QDs capped with C11 compared with those capped with OA. Nanosecond time-resolved PL experiment shows evidence of singlet transfer with Förster resonance energy transfer (FRET) efficiency of 39% for the QDs in solution, while the efficiency of this process amounted to 15.6% for a PVK film doped with 30 wt% of the QDs. The smaller efficiency of the singlet transfer compared to the overall efficiency of energy transfer, suggested by the stationary PL spectra suggests an important role for triplet energy transfer. Electroluminescent devices were prepared with the structure; ITO/PEDOT:PSS/doped PVK with C11 capped QDs/Butyl PBD/Aluminum. Upon applying voltage, the devices show pure blue electroluminescence at low concentration of QDs (10 wt%) with a turn on voltage close to 6V.Keywords: Colloidal quantum dots, organic light emitting diodes, electroluminescence, blue OLEDs, energy transfer, triplet transfer, organic electronics, PVK INTRODUCTIONColloidal semiconductor quantum dots (QDs) are a relatively a new class of materials for optoelectronics. Due to their unique properties, e.g., tunable emission wavelength, they are attractive for many applications such as light emitting diodes, solar cells, and lasers [1-2]. Among them, cadmium selenide (CdSe) QDs have become a bench mark material for research on colloidal nanomaterials for (electro)luminesncence applications due to the tunability of their emission over the visible range between 475 and 670 nm upon increasing QD size [3]. To use QDs as a light source however requires also a the absence of (photo)chemical degradation and a high luminescence quantum yield (QY). These can be fulfilled by surface passivation with inorganic compounds which have broader band gap that encompasses the bandgap of the QD core, so-called core/shell nanostructure (type I) [2,[4][5].

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“…18 Among organic molecules, 1,1,4,4-tetraphenyl-1,3-butadiene 19 (TPB) is well-known and has recently attracted attention as electro-active molecule, as a highly efficient blue emitting electroluminescent dye, or high-energy emitter in organic white-light emitting devices. [20][21][22][23][24] For example, TPB has been used by Wen et al 21 for the preparation of singlelayer organic electroluminescent thin-film devices. Another reason which makes TPB interesting is the possibility to obtain aggregation-induced emission (AIE).…”

Section: Introductionmentioning

confidence: 99%

“…26 In general, the photoluminescence properties of the TPB molecules have been widely investigated. [20][21][22][23][24][27][28][29] However, most of the reported optical measurements are for TPB solutions, polymeric matrixes, or polycrystalline films and are mainly limited to emission with little discussion on the origin of the observed transitions. Interestingly for both applications and the comprehension of the intrinsic properties, TPB forms crystals which maintain intense blue emission.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic optical functions of α-1,4,4-tetraphenyl-1,3-butadiene

Tavazzi

Mora

Alessandrini

et al. 2011

The Journal of Chemical Physics

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One of the known monoclinic polymorphs of 1,1,4,4-tetraphenyl-1,3-butadiene was grown by the floating-drop technique. This material is of interest for blue emitting devices and for fundamental studies on intermolecular interactions, excited states and vibronic coupling in the fields of chemical physics and materials science. Polarized UV-visible spectra are reported. The origin of the optical bands is resolved. The results give information on the intermolecular interactions and are compared with theoretical predictions and modeling. The full material dielectric tensor is provided, as deduced from generalized spectroscopic ellipsometry. Details on the use of this technique on strongly anisotropic and absorbing molecular materials are given. Some typical features of the optical spectra are also demonstrated to be very sensitive to the presence of misaligned domains, which, in our samples, are found to be rotated around the normal to the surface and whose amount is determined. The method allows discriminating among monocrystals, in-plane polycrystalline samples, layered samples formed by misaligned successive layers, or samples with both types of disorder. Two independent parameters giving the fraction of misaligned domains or layers are suggested for the characterization and optimization of the growth and deposition of molecular organic materials.

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Influence of oligothiophene layer on PVK-based blue light-emitting diode

Cited by 14 publications

References 8 publications

Novel crown-containing 3-styryl derivatives of oligothiophenes: synthesis, structure, and optical and electrochemical characteristics

Novel crown-containing 3-styryl derivatives of oligothiophenes: synthesis, structure, and optical and electrochemical characteristics

Blue light-emitting-diodes from poly (N-vinylcarbazole) doped with colloidal quantum dots encapsulated with carbazole terminated ligand: spectroscopic studies and devices

Anisotropic optical functions of α-1,4,4-tetraphenyl-1,3-butadiene

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