Electronic structure studies of conducting polymers by electron energy-loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 160-161
Author(s):  
J. Fink
Keyword(s):  
Electronic Structure ◽  
Conducting Polymers ◽  
Conjugated Polymers ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Light Emitting ◽  
One Dimensional ◽  
New Class ◽  
Electrical Conductivities ◽  
Electron Energy Loss

Conducting polymers comprises a new class of materials achieving electrical conductivities which rival those of the best metals. The parent compounds (conjugated polymers) are quasi-one-dimensional semiconductors. These polymers can be doped by electron acceptors or electron donors. The prototype of these materials is polyacetylene (PA). There are various other conjugated polymers such as polyparaphenylene, polyphenylenevinylene, polypoyrrole or polythiophene. The doped systems, i.e. the conducting polymers, have intersting potential technological applications such as replacement of conventional metals in electronic shielding and antistatic equipment, rechargable batteries, and flexible light emitting diodes.Although these systems have been investigated almost 20 years, the electronic structure of the doped metallic systems is not clear and even the reason for the gap in undoped semiconducting systems is under discussion.

Light-Emitting Diodes Based on Conjugated Polymers: Control of Colour and Efficiency

1992 ◽  
Vol 247 ◽  
Author(s):  
Paul L. Burn ◽  
A. B. Holmes ◽  
A. Kraft ◽  
A. R. Brown ◽  
D. D. C. Bradley ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Conjugated Polymers ◽  
Light Emitting Diodes ◽  
Fold Increase ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Metal Contacts ◽  
Light Emitting ◽  
Lithographic Patterning ◽  
Energy Gaps

ABSTRACTStudies of the effect of different electrode combinations on the device characteristics of simple three layer light-emitting diodes (LEDs) prepared with poly(ρ-phenylenevinylene) (PPV) as the emissive layer sandwiched between two metal contacts have shown that it is generally more difficult to inject electrons than holes. In order to improve the efficiency of such devices it is, therefore, necessary to develop methods to enhance the injection of electrons and we illustrate here one example where we have successfully achieved this by the introduction of a further, electron transport, layer. The result is an eight fold increase in efficiency over our best three layer PPV devices. The efficiency is also dependent on the details of the polymer electronic structure and using a family of copolymers we have been able to produce enhancements in efficiency to values of up to 30 times that of the corresponding PPV devices. Variations in the polymer electronic structure also affect the colour of emission and the same family of copolymers allow control of emission colour from blue/green to orange/red. Supramolecular control of the copolymer electronic structure can be achieved by lithographic patterning and we show that it is possible to produce regions within a single polymer film that possess different π-π* energy gaps.

Organic Syntheses and Characteristics of Novel Conjugated Polymers for AMOLEDs

2010 ◽  
Vol 75 ◽  
pp. 91-96
Author(s):  
Su Hee Song ◽  
Young Eup Jin ◽  
Joo Young Shim ◽  
Kwang Hee Lee ◽  
Hong Suk Suh
Keyword(s):  
Conjugated Polymers ◽  
Blue Emission ◽  
Wavelength Region ◽  
Emission Spectra ◽  
Polymer Backbone ◽  
Light Emitting ◽  
Long Wavelength ◽  
New Class ◽  
Solid Thin Films ◽  
Pl Emission

Conjugated polymers with a stabilized blue emission are of importance for the realization of large flat panel AMOLED displays using polymer light-emitting diodes. Several novel conjugated polymers using newly developed templates for the stabilized EL emission are reported. Poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) is a new class of blue-emitting polymers utilizing a new back-bone. This material emits a efficient blue EL without exhibiting any unwanted peak in the long wavelength region (green region) even after prolonged annealing at an elevated temperature of 150oC in air, or operation of the device. New electroluminescent spiro-PCPPs, poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene))) (spiro-PCPP-alt-PCPP) and poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(1,4-phenylene)) (spiro-PCPPP), have been synthesized by the Suzuki polymerization. The PL emission spectra of polymers in THF solution show a same maximum peak at 397 nm. The maximum PL emission spectra of polymers appeared at around 463 and 456 nm in solid state, respectively. The PL spectra in solid thin films show more red-shifted over 60 nm than solution conditions. The blue emissions at 400-409 nm for the π–π* transitions of conjugated polymer backbone are almost completely quenched or decreased.

scholarly journals Fast and Selective Post-Polymerization Modification of Conjugated Polymers Using Dimethyldioxirane

2019 ◽  
Author(s):  
Emmanuel Reichsöllner ◽  
Adam Creamer ◽  
Shengyu Cong ◽  
Abby Casey ◽  
Simon Eder ◽  
...  
Keyword(s):  
Solar Cells ◽  
Reaction Time ◽  
Conjugated Polymers ◽  
Functional Groups ◽  
Material Properties ◽  
Conjugated Polymer ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Side Product ◽  
Work Up

Modification of functional groups attached to conjugated polymer backbones can drastically alter the material properties. Oxidation of electron-donating thioalkyl substituents to electron-withdrawing sulfoxides or sulfones is a particularly effective modification. However, so far, this reaction has not been studied for the modification of conjugated polymers used in organic electronics. Crucial questions regarding selectivity and reaction time waited to be addressed. Here, we show that the reaction is highly selective and complete within just a few minutes when using dimethyldioxirane (DMDO) for the oxidation of thioalkyl substituents attached to the well investigated conjugated polymers poly(9-(1-octylnonyl)carbazole-alt-4,7-dithienylbenzothiadiazole) (PCDTBT) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). The selectivity was confirmed by comparison with polymers obtained from pre-oxidized monomers and by control experiments using related polymers without thioalkyl substituents. Using DMDO, the oxidation yields acetone as the only side-product, which reduces the work-up to mere evaporation of solvents and excessive reagent. Our results show that this oxidation is an exciting method for the preparation of electron-deficient conjugated polymers. It may even allow the preparation of electron acceptors for solar cells directly from the electron donors.

Electronic structure of pyrrole-based conducting polymers: An electron-energy-loss-spectroscopy study

1986 ◽  
Vol 34 (2) ◽  
pp. 1101-1115 ◽  
Author(s):  
J. Fink ◽  
B. Scheerer ◽  
W. Wernet ◽  
M. Monkenbusch ◽  
G. Wegner ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Conducting Polymers ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Spectroscopy Study ◽  
Electron Energy Loss

Poly(bithiazole)s: A New Class of Conjugated Polymers for Polymer-Based Light-Emitting Diodes

1996 ◽  
Vol 424 ◽  
Author(s):  
J. K. Politis ◽  
J. Nanos ◽  
Yi He ◽  
J. Kanicki ◽  
M. D. Curtis
Keyword(s):  
Conjugated Polymers ◽  
High Stability ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
New Class

AbstractA new class of conjugated polymers have been synthesized based on the bithiazole moiety. The photoluminescence (PL) of these polymers ranges throughout the visible, from blue-green to red. These materials also show high stability, both thermal and oxidative. Therefore, it appears that this class of polymers are good candidates for polymer-based light emitting diodes.

scholarly journals Fast and Selective Post-Polymerization Modification of Conjugated Polymers Using Dimethyldioxirane

2019 ◽  
Author(s):  
Emmanuel Reichsöllner ◽  
Adam Creamer ◽  
Shengyu Cong ◽  
Abby Casey ◽  
Simon Eder ◽  
...  
Keyword(s):  
Solar Cells ◽  
Reaction Time ◽  
Conjugated Polymers ◽  
Functional Groups ◽  
Material Properties ◽  
Conjugated Polymer ◽  
Electron Acceptors ◽  
Electron Donors ◽  
Side Product ◽  
Work Up

Modification of functional groups attached to conjugated polymer backbones can drastically alter the material properties. Oxidation of electron-donating thioalkyl substituents to electron-withdrawing sulfoxides or sulfones is a particularly effective modification. However, so far, this reaction has not been studied for the modification of conjugated polymers used in organic electronics. Crucial questions regarding selectivity and reaction time waited to be addressed. Here, we show that the reaction is highly selective and complete within just a few minutes when using dimethyldioxirane (DMDO) for the oxidation of thioalkyl substituents attached to the well investigated conjugated polymers poly(9-(1-octylnonyl)carbazole-alt-4,7-dithienylbenzothiadiazole) (PCDTBT) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). The selectivity was confirmed by comparison with polymers obtained from pre-oxidized monomers and by control experiments using related polymers without thioalkyl substituents. Using DMDO, the oxidation yields acetone as the only side-product, which reduces the work-up to mere evaporation of solvents and excessive reagent. Our results show that this oxidation is an exciting method for the preparation of electron-deficient conjugated polymers. It may even allow the preparation of electron acceptors for solar cells directly from the electron donors.

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