We report highly bright and efficient inverted structure quantum dot (QD) based light-emitting diodes (QLEDs) by using solution-processed ZnO nanoparticles as the electron injection/transport layer optimizing energy levels with organic hole transport layer. have successfully demonstrated red, green, blue QLEDs showing maximum luminances up to 23,040, 218,800, 2250 cd/m(2), external efficiencies of 7.3, 5.8, 1.7%, respectively. It is also noticeable that they showed turn-on voltages low...

In this article, the design paradigm involving molecular weight, alkyl substituents, and donor-acceptor interaction for poly[2,6-(4,4-bis-alkyl-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (cyclopentadithiophene-benzothiadiazole) copolymer (CDT-BTZ) toward field-effect transistors (FETs) with ultrahigh mobilities is presented discussed. It shown that weight plays a key role in improving hole mobilities, reaching an exceptionally high value of up to 3.3 cm(2)...

Porous thin-film dielectric insulators with significantly lower constants are expected to have great impact on the fabrication of ever smaller semiconductor devices and chips higher packaging densities. Here two routes preparation such nanoporous thin films presented. A method has been developed that generates polyimide foams nanopores from a block copolymer in which dispersed phase undergoes thermolysis. The other approach described uses branched, highly functional macromolecules as...

We present here an optimized united atom model that is able to reproduce properties of melts n-alkane chains varying molecular weights. This differs from previous models in the Lennard-Jones well depth for terminal methyl group (0.2264 kcal/mol) methylene units (0.093 kcal/mol). The position minimum at 4.5 Å both units. Properties n-C44H90 this are compared with experiments and those explicit model. Good agreement experiment obtained static melt, specifically P–V–T behavior, chain...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular order in condensed states of semiflexible poly(amic acid) and polyimideNobuyuki Takahashi, Do Y. Yoon, William ParrishCite this: Macromolecules 1984, 17, 12, 2583–2588Publication Date (Print):December 1, 1984Publication History Published online1 May 2002Published inissue 1 December 1984https://doi.org/10.1021/ma00142a021RIGHTS & PERMISSIONSArticle Views770Altmetric-Citations200LEARN ABOUT THESE METRICSArticle Views are the...

A comprehensive structural and electrical characterization of solution-processed blend films 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) semiconductor poly(α-methylstyrene) (PαMS) insulator was performed to understand optimize the films, which are very attractive as active layer in organic thin-film transistors (OTFTs). Our study, based on careful measurements specular neutron reflectivity grazing-incidence X-ray diffraction, showed that blends with a low molecular-mass...

We demonstrate tuning of hole injection barriers in bottom contact triisopropylsilylethynyl pentacene (TIPS-pentacene) organic thin film transistors (OTFTs) by forming the self-assembled monolayers (SAMs) thiophenol, 4-fluorothiophenol, or pentafluorothiophenol on pristine Ag electrode. The work functions SAM-treated electrodes are measured Kelvin probe method. TIPS-pentacene OTFT devices were fabricated a drop-cast method with micropipette like an inkjet printing. OTFTs...

In this paper, we present the results of Monte Carlo simulations static properties polymer melts confined between hard walls. The are conducted in canonical ensemble with a method that is combination reptation and crankshaft motions. 1250 chains each comprising 100 connected beads placed box which allows for simulation typical melt two plates at separation 51 bead diameters. Noncovalently bonded assumed to interact an empirical 6-12 Lennard-Jones potential has parameters chosen simulate...

We present a novel method of preparing highly efficient and stable second-order nonlinear optical (NLO) polymers via chemical cross-linking induced vitrification under electric field. In this soluble prepolymer is first prepared that contains sites attached to the NLO-active groups. Upon samples desired thicknesses, heated (precured) enable some thus increase glass transition temperature (Tg) an optimum for poling. The precured polymer then above its Tg subjected high field obtain alignment...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConformational Characteristics of PolystyreneD. Y. Yoon, P. R. Sundararajan, and J. FloryCite this: Macromolecules 1975, 8, 6, 776–783Publication Date (Print):November 1, 1975Publication History Published online1 May 2002Published inissue 1 November 1975https://pubs.acs.org/doi/10.1021/ma60048a019https://doi.org/10.1021/ma60048a019research-articleACS PublicationsRequest reuse permissionsArticle Views1788Altmetric-Citations217LEARN ABOUT THESE...

Thin films for optical second-harmonic generation (SHG) were prepared from a newly designed and synthesized amorphous polymer that incorporated high density of active nonlinear groups (p-nitroaniline as attached side groups). For alignment the very electric field was applied by corona discharge to above Tg (125 °C). The subsequent freezing process resulted in film initially exhibiting second-order coefficient, d33=31 pm/V, measured Maker-fringe technique, plus excellent thermal, mechanical,...

Abstract An efficient synthesis of 9,9‐bis(2‐ethylhexyl)fluorene oligomers up to the heptamer is reported, with repetitive Suzuki and Yamamoto coupling reactions employed in synthesis. The key steps for preparation essential intermediates include Pd‐catalyzed transformation aryl bromides boronic esters (Miyaura reaction) application much higher reactivity over cross‐coupling reaction diazonium salts. Variation UV/Vis absorption photoluminescence characteristics chain length reported....

Abstract A comprehensive structure and performance study of thin blend films the small‐molecule semiconductor, 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl)anthradithiophene (diF‐TESADT), with various insulating binder polymers in organic thin‐film transistors is reported. The vertically segregated composition profile nanostructure are characterized by a combination complementary experimental methods including grazing incidence X‐ray diffraction, neutron reflectivity, variable angle...

Positronium annihilation lifetime spectroscopy is used to determine the pore-size distribution in low-dielectric thin films of mesoporous methylsilsesquioxane. A physical model positronium trapping and annihilating isolated pores presented. The systematic dependence deduced on pore shape/dimensionality sample temperature predicted using a simple quantum mechanical calculation rectangular pore. comparison with an electron microscope image

An ensemble of H(CH2OCH2)12H chains has been studied by molecular dynamics simulations as both melt and unperturbed phantom a model system to investigate condensed phase effects on chain conformations poly(oxyethylene) (POE). In addition, high weight POE in the have determined small-angle neutron scattering (SANS) experiments over temperature range 347−459 K. Our show that are more extended than which represent ϑ solution. Moreover, exhibit negative coefficient dimensions contrast positive...

We have investigated the dynamic structure factor for single-chain relaxation in a polyethylene melt by means of molecular dynamics simulations and neutron spin echo spectroscopy. After accounting 20% difference chain self-diffusion coefficient between simulation experiment we find perfect quantitative agreement intermediate over whole range momentum transfer studied. Based on this one can test experimental results deviations from standard Rouse behavior reported so far only computer polymer...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTForce field for simulations of 1,2-dimethoxyethane and poly(oxyethylene) based upon ab initio electronic structure calculations on model moleculesGrant D. Smith, Richard L. Jaffe, Do Y. YoonCite this: J. Phys. Chem. 1993, 97, 49, 12752–12759Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOff-lattice Monte Carlo simulations of polymer melts confined between two plates. 2. Effects chain length and plate separationSanat K. Kumar, Michele Vacatello, Do Y. YoonCite this: Macromolecules 1990, 23, 8, 2189–2197Publication Date (Print):April 1, 1990Publication History Published online1 May 2002Published inissue 1 April 1990https://pubs.acs.org/doi/10.1021/ma00210a012https://doi.org/10.1021/ma00210a012research-articleACS PublicationsRequest...

We present in this work results from atomistic molecular dynamics simulations of a n-C100H202 melt. This represents first effort to simulate fully equilibrated ensemble chains sufficient length follow Gaussian statistics and hence Rouse-like chain dynamics, employing well-validated, realistic potentials. In order allow full equilibration the were performed at experimental densities high temperatures (≥450 K). Here we report on static dynamic properties melt obtained two models, united atom...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConformation of 1,2-dimethoxyethane from ab initio electronic structure calculationsRichard L. Jaffe, Grant D. Smith, and Do Y. YoonCite this: J. Phys. Chem. 1993, 97, 49, 12745–12751Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://pubs.acs.org/doi/10.1021/j100151a020https://doi.org/10.1021/j100151a020research-articleACS PublicationsRequest reuse permissionsArticle...

Extending the novel method of Eich et al. [J. Appl. Phys. 66, 3241 (1989)] to prepare highly stable second-order nonlinear optical (NLO) polymers via chemical cross-linking under electric field, we have obtained a new polymer exhibiting large and nonlinearities after relaxation at 80 °C. This was achieved by forming network from two NLO-active monomers, bifunctional N,N-(diglycidyl)-4-nitroaniline trifunctional N-(2-aminophenyl)-4-nitroaniline. Here, every NLO moiety is connected single...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of a New Crystal Form (αp) Poly(vinylidene fluoride) under Electric FieldD. Naegele, D. Y. Yoon, and M. G. BroadhurstCite this: Macromolecules 1978, 11, 6, 1297–1298Publication Date (Print):November 1, 1978Publication History Published online1 May 2002Published inissue 1 November 1978https://pubs.acs.org/doi/10.1021/ma60066a051https://doi.org/10.1021/ma60066a051research-articleACS PublicationsRequest reuse permissionsArticle...

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTComparison of Ring and Linear Polyethylene from Molecular Dynamics SimulationsKahyun Hur, Roland G. Winkler, Do Y. YoonView Author Information Department Chemistry, Seoul National University, 151-747, Korea, Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Germany Cite this: Macromolecules 2006, 39, 12, 3975–3977Publication Date (Web):May 17, 2006Publication History Received6 February...

The dynamical characteristics of ring and linear polyethylene (PE) molecules in the melt have been studied by employing atomistic molecular dynamics simulations for PEs with carbon atom numbers N up to 500 rings 1500. single-chain dynamic structure factors S(q,t) from entangled PE chains, which show strong deviations Rouse predictions, exhibit quantitative agreement experimental results. Ring chains also a transition Rouse-type dynamics, as indicated mean-square monomer displacements g1(t)....