TY  - JOUR
A1  - Wong, J. E.
A1  - Detert, H.
A1  - Brehmer, Ludwig
A1  - Schrader, Sigurd
T1  - Green light-emitting devices based on soluble oligo(phenylenevinylenes)
N2  - In this work, we report our investigations on the film-forming properties as well as the optical and electroluminescent characterisations of a series of lateral-substituted soluble oligo(phenylenevinylenes) of various conjugation length. Preliminary investigations show that these materials are potential candidates for use in organic light-emitting devices (OLEDs). Two types of OLEDs were fabricated: single layer (SL) and single heterostructure (SHS), with poly(p-phenylenevinylene) (PPV) as hole transporting layer. Our best results were obtained with single layer device emitting green light with a luminance of 0.18 cd m(-2) and 0.24 cd m(-2) at a driving voltage of 10 V. (c) 2004 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0169-4332
ER  - 
TY  - BOOK
A1  - Smertenko, P.
A1  - Fenenko, L.
A1  - Brehmer, Ludwig
A1  - Schrader, Sigurd
T1  - Differential approach to the study of integral characteristics in polymer films
N2  - The differential approach is based on the determination of dimensionless differential slope, for instance, of current-voltage characteristics (IVC), I=f(V). This slope (a) is given by formula alpha=d(lgI)/d(lgV). With such definition the ranges of constancy of the a(V) dependency correspond to the part of IVC characterized by the power behaviour (I similar to V-alpha). The differential slope of alpha(V) dependency gamma = d(lg alpha)/dlgV determines the exponent behaviour of curve (I similar to exp {eV(y)/kT}). Processing by the differential approach of the investigated theoretical or experimental characteristics permits us to determine the peculiarity of charge flow mechanisms, temperature behaviour of conductivity, etc. The theoretical base and some applications of differential approach to the investigation of the current-voltage, temperature and degradation characteristics of the polyaniline and poly(p- phenilenevinilene) based structures have been shown. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Holzer, Wolfgang
A1  - Penzkofer, Alfons
A1  - Schrader, Sigurd
A1  - Grimm, Bernhard
T1  - Photo-physical and lasing characterisation of a polyparaphenylenevinylene (PPV) neat film
N2  - The wave-guided travelling-wave laser action (amplified spontaneous emission) of a neat film of poly(p- phenylenevinylene) (PPV) on a quartz glass substrate prepared by a sulfinyl precursor technique is studied. The samples are transversally pumped with picosecond excitation pulses (wavelength 347.15 nm, duration 35 ps). Lasing occurs at 550 nm. The optical constants of the neat films are determined by transmittance measurements exploiting the multiple beam interference in the transparency region. A fluorescence spectroscopic characterisation is carried out determining the fluorescence quantum distribution, fluorescence quantum yield, degree of fluorescence polarisation, and fluorescence lifetime. The emitting chromophore size (emitting singlet exciton extension) is determined by the ratio of exciton radiative lifetime to repeat-unit based radiative lifetime. The obtained size of about two repeat units is discussed in a disordered solid-state polymer model
Y1  - 2005
SN  - 0306-8919
ER  - 
TY  - JOUR
A1  - Breu, J.
A1  - Stossel, P.
A1  - Schrader, Sigurd
A1  - Starukhin, A.
A1  - Finkenzeller, W. J.
A1  - Yersin, H.
T1  - Crystal structure of fac-Ir(ppy)(3) and emission properties under ambient conditions and at high pressure
N2  - Solution and refinement of the crystal structure of fac-Ir(ppy)(3) is severely hampered by systematic twinning and pseudo-symmetry.fac-Ir(ppy)(3) Crystallizes in the centrosymmetric space group P (3) over bar as has been deduced from single-crystal structure refinement and investigations of the second harmonic generation (SHG) of fac-Ir(ppy)(3) powder as compared to two standard materials. The topology of the molecular packing of fac-Ir(ppy)(3) is identical to the packing observed for [Ru(bpy)(3)](0), however, the site symmetry of all Ir(ppy)(3) molecules is necessarily lowered from D-3 to C-3. Packing motifs with intermolecular "pi-pi interactions" of T-shaped and "shifted pi stack" geometry are realized. The systematic twinning leads to the occurrence of crystalline domains with rigorously alternating chirality within the bulk of the domains but with homochiral fac-Ir(ppy)(3) contacts at the domain interfaces. These differences in packing motifs are displayed in the emission spectra and in the high-pressure-induced shifts of the emission. The emission maximum of the bulk material at 18 350 cm(-1) (545 nm) and of the domain interfaces at 19 700 cm-1 (507 nm) experience for p < 25 kbar and T = 295 K red shifts of Delta nu/Delta p = -(12 +/- 2) cm(-1)/kbar, and -(22 +/- 4) cm(- 1)/kbar, respectively
Y1  - 2005
SN  - 0897-4756
ER  -