Efficient light emitting diodes from polyfluorene copolymer blends

Çırpan, Ali
Karasz, FE
Highly efficient light emitting diodes were obtained by blending blue-emitting poly [(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(N,N'-diphenyl)-N,N-di(p-butyl-oxyphenyl)-1 ,4-diaminobenzene] (1) with green-emitting poly [(9,9-dioctyl-2,7-divinylene-fluorenylene)-alt-co-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (II). Only green emission was obtained from the films of polymer blends and from corresponding double-layer LEDs, indicating an almost complete Forster energy transfer from I to II. These devices show enhanced external quantum efficiency, higher brightness and lowor turn on voltages. Luminance and efficiency of 2.6 x 10(4) cd/m(2) and 2.55%, respectively, were obtained.


High mobility, low voltage operating C-60 based n-type organic field effect transistors
Schwabegger, G.; Ullah, Mujeeb; Irimia-Vladu, M.; Baumgartner, M.; Kanbur, Y.; Ahmed, R.; Stadler, P.; Bauer, S.; Sariciftci, N. S.; Sitter, H. (Elsevier BV, 2011-10-01)
We report on C-60 based organic field effect transistors (OFETs) that are well optimized for low voltage operation. By replacing commonly used dielectric layers by thin parylene films or by utilizing different organic materials like divinyltetramethyldisiloxane-bis(benzocyclo-butene)(BCB), low density polyethylene (PE) or adenine in combination with aluminum oxide (AlOx) to form a bilayer gate dielectric, it was possible to significantly increase the capacitance per unit area (up to two orders of magnitude)...
DOGAN, S; Akbulut, Ural; Toppare, Levent Kamil (Elsevier BV, 1992-11-01)
We describe an electrochemical synthesis of a conducting composite of polyaniline. Poly(bisphenol A carbonate) was used as the insulating polymer matrix. Composite characterization was made using FT-IR, SEM and DSC data. The conductivities of the composites seemed to be in the order of pure polyaniline as prepared by the same method. Moreover, the above-mentioned methods reveal that the resultant composites have different properties compared to a simple mechanical mixture of the two polymers.
Computational modeling of isothermal decay curves of trapping centers in TlGaSeS layered single crystals
Kucuk, Ilker; Yildirim, Tacettin; Hasanlı, Nızamı; Ozkan, Husnu (Elsevier BV, 2010-10-08)
This paper presents a new approach based on multilayered perceptrons (MLPs) to compute the isothermal decay curves of trapping centers in undoped TlGaSeS layered crystals. The MLP has been trained by a Genetic Algorithm (GA). The results obtained using the MLP model were tested with an untrained experimental data. The comparison has shown that the proposed model can predict more accurately and easily the isothermal decay curves.
Hasanlı, Nızamı; MELNIK, NN; RAGIMOV, AS (Wiley, 1983-01-01)
Measurements are made of polarized Raman scattering and infrared reflection spectra of twenty two compositions of GaS1‐xSex layer mixed crystals grown by the Bridgman method. Besides the usual one‐mode and two‐mode behaviours of phonon modes, a number of more complex dependences characterized by the appearance of additional bands in the spectra of mixed crystals are observed. Their appearance is accounted for by the uncovering of the Brillouin zone due to the disturbance of the periodicity of the crystal la...
Characteristics of HfO2 and SiO2 on p-type silicon wafers using terahertz spectroscopy
Altan, Hakan; Pham, D.; Grebel, H.; Federici, J. F. (IOP Publishing, 2007-05-01)
The effect of high-kappa dielectric HfO2 films on 200 mm diameter p-type silicon substrates was investigated and compared with conventional dielectric material, SiO2. We employed all-optical characterization methods using terahertz (THz) time-domain spectroscopy and visible cw pump/THz probe spectroscopy. Measurements were performed on two sets of samples, each set containing both HfO2 and SiO2 coated wafers with varying thickness of oxide layer. One set had a protective coating of either photoresist or Si3...
Citation Formats
A. Çırpan and F. Karasz, “Efficient light emitting diodes from polyfluorene copolymer blends,” SYNTHETIC METALS, pp. 195–198, 2005, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/35908.