Enhanced luminance in polymer composite light emitting devices

Carter, S. A.; Scott, J. C.; Brock, Phillip J.

doi:10.1063/1.119848

Cited by 223 publications

(129 citation statements)

References 11 publications

(14 reference statements)

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“…Similar phenomena obtained for nanohybrid layers were explained due to the TiO 2 /polymer boundaries causing differences in band gap between oxide nanoparticles and the conjugate polymer [17]. Based on these results we take an explanation for the improved performance which supports the suggestion by Carter et al [16]. It is suggested by the change in device morphology caused by the incorporation of nanoparticles into the solution.…”

Section: Resultssupporting

confidence: 77%

“…For instance, in [15] the authors attributed this enhancement to stimulated emission of optically-pumped MEH-PPV films when TiO 2 particles were embedded in. Whereas, in [16] by their obtained results the author indicates that no evidence of line narrowing or changes in the line shape are observed at different voltages implying that the mechanism for improved performance is distinctly different from that found in optically-pumped TiO2/MEH-PPV films. The authors concluded that optical scattering phenomenon is not causing the increase in performance.…”

Section: Resultsmentioning

confidence: 61%

“…The authors concluded that optical scattering phenomenon is not causing the increase in performance. Another possible explanation is that the nanoparticle surfaces increase the probability of electron-hole recombination; however, again this would result in a change in the external quantum efficiency, rather than the current density as is observed [16].…”

Section: Resultsmentioning

confidence: 86%

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Preparation and characterization of nanostructured composite films for organic light emitting diodes

Định

Hà

Long

et al. 2009

J. Phys.: Conf. Ser.

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 86%

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Preparation and characterization of nanostructured composite films for organic light emitting diodes

Định

Hà

Long

et al. 2009

J. Phys.: Conf. Ser.

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“…These results indicate that the Aucapped TiO 2 nanocomposite incorporated in the EL polymer facilitates the increase in charge carriers by roughness assisted tunneling, as reported by Park et al 15 It is believed that the nanocomposite adhere to the ITO anode by electrostatic forces; thereby, the nanomorphologically roughened EL layer causes a larger interfacial contact area between the cathode ͑Ca͒ and EL polymer that can be responsible for the enhanced electrical performance of HPLED. 8,16 Moreover, the nanocomposite adhered on the ITO layer behaves like field emitters and thus the charges are gathered around the sharp clusters of nanocomposite. The charges can easily tunnel into the MEH-PPV EL layer facilitating a current flow into HPLED.…”

Section: -mentioning

confidence: 99%

“…6,7 This goal was realized by blending the electron transporting nanoparticles into luminescent polymers, thereby enhancing performance without use of complicated structures. 8 The purpose of the present study was to increase the brightness of HPLED by using hybrid nanocomposite polymer systems. We employed titanium oxide ͑TiO 2 ͒ capped with gold ͑Au͒, which has potential for use in energy-conversion devices.…”

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confidence: 99%

Improved performance of polymer light-emitting diodes with nanocomposites

Hussain

Neppolian

Kim

et al. 2009

Applied Physics Letters

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The characteristics of a hybrid polymer light-emitting diode (HPLED) with an active layer of poly [2-methoxy,5-(2-ethylhexoxy)-1,4-phenylenevinylene] blended with Au-capped TiO2 nanocomposites are reported. Both the increased current in the active layer and low turn-on voltage were attributed to incorporation of Au-capped TiO2 in the electroluminescent polymer. The maximal brightness of 11 630 cd/m2 was observed in HPLED with a 1:1 ratio of Au-capped TiO2. The enhanced performance was attributed to the roughness assisted charge transport induced by the Au-capped TiO2 nanocomposites in the active polymer.

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Self-Assembled Nanocomposite Polymer Light-Emitting Diodes with Improved Efficiency and Luminance

et al. 1999

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Hybrid organic and nanoparticle-based systems have been recently studied as prospective materials for optoelectronics applications because they combine the advantages of organic polymers with those of inorganic clusters. For photonic applications, nanoparticles enable a wider variation of the dielectric constant (refractive index) and charge transport properties than polymers. [1] The mesoscale character of nanoparticle dimensions, corresponding to the wavelength of visible light, allows for the assembly of superlattice structures with possible optical band gap properties [2] or with microcavity effects for polymer lasing. [3] Highly efficient photovoltaics can be made through organic dye sensitization of TiO 2 and related nanoparticles. [4,5] More recently, dielectric oxide nanoparticles have been shown to modify the charge transport in polymer light-emitting diodes, resulting in an increase in both the current density and light emission. [6] In this paper, we show that nanoparticles assembled at a semiconducting polymer/electrode interface can also affect charge injection into polymer lightemitting diodes. For the case of negatively charged dielectric SiO 2 monolayers assembled at the anode interface, external electroluminescence quantum efficiencies approaching theoretical limits for radiative singlet decay can be achieved. Moreover, nanoparticle monolayers result in enhanced luminances at lower drive voltages, similar to what has been achieved with conducting polymer layers. These results indicate that interfacial nanoparticle layers offer a general method for enhancing the local electric field across the polymer/anode interface, providing versatility for improving performance of polymer optoelectronic devices.Since the discovery of electroluminescence in polymers, [7] charge transport and injection in semiconducting polymers has been actively studied with the goal of achieving bright and highly efficient polymer light-emitting diodes operating at low electric fields. A key requirement for high electroluminescent efficiencies is balanced injection of holes and electrons at the anode and cathode interfaces, respectively. Such balance can be dramatically affected by controlling injection through modification of the interface between the semiconducting polymer and the electrodes. Although both electrode surfaces can be modified in principle, the modification of the indium tin oxide (ITO) anode is more common due to the atmospheric stability of the ITO surface that enables ªwetº preparation stages (cleaning, chemical modification, and spinning) before the vacuum stages such as evaporation of a metal cathode and protective coatings. For materials limited by holeinjection, the device efficiency can be improved by inserting a hole transporting layer that enables smaller tunneling barriers, or Ohmic injection, from the anode into the highest occupied molecular orbital (HOMO) of the polymer. [8± 11] For electron-limited materials, the quantum efficiency can be improved by inserting a layer that effectively blocks el...

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Enhanced luminance in polymer composite light emitting devices

Cited by 223 publications

References 11 publications

Preparation and characterization of nanostructured composite films for organic light emitting diodes

Preparation and characterization of nanostructured composite films for organic light emitting diodes

Improved performance of polymer light-emitting diodes with nanocomposites

Self-Assembled Nanocomposite Polymer Light-Emitting Diodes with Improved Efficiency and Luminance

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