Efficient full-colour electroluminescence and stimulated emission with polyphenylenes

Leising, G.; Tasch, S.; Brandstätter, C.; Graupner, W.; Hampel, Silke; List, Emil; Meghdadi, F.; Zenz, Christian; Schlichting, P.; Rohr, U.; Geerts, Yves; Scherf, Ullrich; Müllen, Kläus

doi:10.1016/s0379-6779(97)03972-6

Cited by 66 publications

(11 citation statements)

References 45 publications

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“…[38][39][40][41][42] In addition, Me-LPPP has been shown to be a very promising material for use in organic solid-state lasers with optically pumped lasing having been observed in both waveguide and distributed feedback configurations. [43][44][45][46][47] The phenyl-substituted polymer Ph-LPPP 3c shows a similar emission to Me-LPPP with emission maxima at 460 and 490 nm, but with an additional long wavelength band with wellresolved maxima at 600 and 650 nm. [48] These proved to be emission from triplet states (phosphorescence) arising from palladium-containing centers (the polymer contains %80 ppm of palladium) bound into the polymer chain.…”

Section: Ladder-type Poly(para-phenylene)s (Lppps)mentioning

confidence: 93%

“…Blue‐green‐emitting LEDs have been constructed using Me‐LPPP with efficiencies of up to 4% 38–42. In addition, Me‐LPPP has been shown to be a very promising material for use in organic solid‐state lasers with optically pumped lasing having been observed in both waveguide and distributed feedback configurations 43–47. The phenyl‐substituted polymer Ph‐LPPP 3c shows a similar emission to Me‐LPPP with emission maxima at 460 and 490 nm, but with an additional long wavelength band with well‐resolved maxima at 600 and 650 nm 48.…”

Section: Ladder‐type Poly(para‐phenylene)s (Lppps)mentioning

confidence: 99%

See 1 more Smart Citation

Oligomers and Polymers Based on Bridged Phenylenes as Electronic Materials

Grimsdale

Müllen

2007

Macromol. Rapid Commun.

188

154

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The synthesis, properties, and application in electronic devices of ladder and step‐ladder phenylene‐based oligomers and polymers are reviewed with an emphasis on control of properties by synthetic design. Bridged polyphenylenes can be prepared with a range of different amounts and types of bridges. Fully bridged polymers suffer the problem of incomplete formation of bridges during polymer analogous reactions. This problem is surmounted by the synthesis of regular stepladder polymers in which the monomers are well‐characterized oligo(ladder‐phenylene)s. By controlling the degree of bridging and thus the planarity of the polymer, its optical properties can be tuned. The optical and electronic properties can be further controlled by means of the type of bridges used.

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Section: Ladder-type Poly(para-phenylene)s (Lppps)mentioning

confidence: 93%

Section: Ladder‐type Poly(para‐phenylene)s (Lppps)mentioning

confidence: 99%

Oligomers and Polymers Based on Bridged Phenylenes as Electronic Materials

Grimsdale

Müllen

2007

Macromol. Rapid Commun.

188

154

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“…Second, there is a huge disparity between hole and electron mobilities in semiconducting polymers, thus precluding balanced charge transport in the devices. Commonly studied EL polymers such as PPV,1a polyphenylenes, polyfluorenes, polythiophenes, and their derivatives are p-type (hole transport) polymers which have hole mobilities that are orders of magnitude larger than electron mobilities, relatively small barriers to hole injection from indium−tin oxide (ITO, Φ a ∼ 4.7−4.8 eV),19a and very large barriers to electron injection from air-stable cathodes such as aluminum ( Φ c ∼4.0−4.3 eV) 19b. Two-layer polymer/polymer heterojunction LEDs, schematically shown in Figure b, have been found to have dramatically improved EL efficiency and brightness, 8a,8b, compared to the one-layer devices (Figure a), as also found in multilayered organic/organic diodes …”

Section: Introductionmentioning

confidence: 99%

Electroluminescence of Multicomponent Conjugated Polymers. 1. Roles of Polymer/Polymer Interfaces in Emission Enhancement and Voltage-Tunable Multicolor Emission in Semiconducting Polymer/Polymer Heterojunctions

2000

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Effects of the electronic structure of polymer/polymer interfaces on the electroluminescence efficiency and tunable multicolor emission of polymer heterojunction light-emitting diodes were explored by a series of 16 n-type conjugated polymers with varying electron affinities and ionization potentials in conjunction with poly(p-phenylenevinylene). Efficiency and luminance of diodes of the type indium-tin oxide/poly(p-phenylenevinylene)/n-type polymer/aluminum were maximized and were as high as 3% photons/electron and 820 cd/m 2 , respectively, when the energetics at the polymer/polymer interface favored electron transfer while disfavoring hole transfer. Energetic barrier to electron transfer at the polymer/ polymer interface was more important to electroluminescence efficiency and diode luminance than injection barrier at the cathode/polymer interface. By a judicious choice of the relative layer thicknesses and the components of the bilayer heterojunctions, the rate of both electron and hole transfer across the polymer/ polymer interface can be regulated by the applied voltage, resulting in continuous voltage tunability of emission colors. The voltage tunable multicolor emission is exemplified by red (5 V) T yellow (9 V) T green (12 V) and other intermediate color switching in poly(p-phenylenevinylene)/poly(2,6-(4-phenyl)quinoline) (PPQ) diodes. The multicolors obtained from a single heterojunction diode by varying the applied voltage originated from the mixing of the component emission spectra in varying proportions facilitated by interfacial charge transfer and finite size effects. Electroluminescence microscopy was used to directly image the multicolor diodes. These results suggest that the electronic structure of polymer/polymer interfaces and finite size effects dominate the emission features and performance of light-emitting devices based on multicomponent polymers such as multilayered thin films, phase-separated blends, and block copolymers. The results also have implications for photovoltaic cells and other optoelectronic devices using conjugated polymers.

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“…Blue-green-emitting LEDs have been constructed using Me-LPPP with efficiencies of up to 4% [45][46][47][48][49]. In addition, Me-LPPP has been shown to be a very promising material for use in organic solid-state lasers with optically pumped lasing having been observed in both waveguide and distributed feedback configurations [50][51][52][53][54]. The phenyl-substituted polymer Ph-LPPP 2c shows emission similar to Me-LPPP with emission maxima at 460 and 490 nm, but with an additional long wavelength band with well-resolved maxima at 600 and 650 nm [55].…”

Section: Lppps With Single-atom Bridgesmentioning

confidence: 99%