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PL Spectroscopy (pl + spectroscopy)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

End-functionalization of semiconducting species with dendronized terpyridine,Ru(II),terpyridine complexes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2009
Elefterios K. Pefkianakis
Abstract Semiconducting oligomers and polymers decorated with two or one dendronized tpy-Ru(II)-tpy metallocomplexes are presented. Initially, free terpyridine end-functionalized semiconducting oligomers (distyrylanthracene, quinquephenylene, mono- and trifluorenes) were prepared while in a second approach, atom transfer radical polymerization was employed for the preparation of side-chain oligomeric and polymeric (oxadiazole)s using a terpyridine initiator. These terpyridine-bearing oligomers and polymers were complexated with a Percec-type first-generation (G1) dendronized terpyridine,Ru(III)Cl3 monocomplex, having two dodecyloxy groups. All oligomeric and polymeric metallocomplexes were characterized via NMR spectroscopies for their structural perfection and via UV-Vis and PL spectroscopies for their optical properties. The existence of the organic semiconducting blocks in combination with the terpyridine,Ru(II),terpyridine groups afforded hybrid metallo-semiconducting species presenting the optical features of both their components. Moreover, their thin-film morphologies were investigated through atomic force microscopy, revealing, in some cases, an organization tendency in the nanometer scale. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1939,1952, 2009 [source]

Amplified Spontaneous Emission of Poly(ladder-type phenylene)s , The Influence of Photophysical Properties on ASE Thresholds,

ADVANCED FUNCTIONAL MATERIALS, Issue 20 2008
Frédéric Laquai
Abstract Amplified spontaneous emission (ASE) of a series of blue-emitting poly(ladder-type phenylene)s (LPPP)s has been studied in thin film polymer waveguide structures. The chemically well-defined step-ladder polymers consist of an increasing number of bridged phenylene rings per monomer unit starting from fully arylated poly(ladder-type indenofluorene) up to poly(ladder-type pentaphenylene). The ASE characteristics of the polymers including the onset threshold values for ASE, the gain and loss coefficients as well as the photoluminescence (PL) properties, i.e., the solid state fluorescence lifetimes, decay kinetics and solid state quantum efficiencies have been studied by time-resolved PL spectroscopy. A fully arylated polyfluorene has been synthesized and its photophysical properties were compared to the step-ladder polymers. Steady-state photoinduced absorption and ultrafast transient absorption spectroscopy have been used to study excited state absorption of singlet and triplet states and polarons present in the solid state. The results demonstrate a minimum regarding the onset threshold value of ASE for a fully arylated poly(ladder-type indenofluorene) and a successive increase of the ASE threshold for the step-ladder polymers with more bridged phenylene rings. In particular, carbazole-containing step-ladder LPPPs exhibit significantly increased ASE threshold values as compared to their carbazole-free analogues due to a pronounced overlap of stimulated emission (SE) and photoinduced absorption (PA). [source]

Multilayer Thin Films by Layer-by-Layer Assembly of Hole- and Electron-Transport Polyelectrolytes: Optical and Electrochemical Properties

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2006
Kyungsun Choi
Abstract Summary: In this paper, we present the synthesis of a series of p-type and n-type semiconducting polyelectrolytes with triarylamine, oxadiazole, thiadiazole and triazine moieties. The synthesized polymeric hole and electron transport materials were examined optically and electrochemically using UV/Vis spectroscopy, PL spectroscopy and CV. Based on the optical and electrochemical data, each of the energy levels were calculated and all values suggested that they were promising hole- (p-type) or electron-transport (n-type) materials for devices. Moreover, the synthesized ionic polymers were suitable for LBL thin film deposition from dilute polymer solutions and the multilayers were fully characterized by UV/Vis, PL spectroscopy and CV. [source]

Observation of 4F3/2,4I15/2 radiative transition in Nd3+ ions in GaLaS glass using frequency-resolved PL spectroscopy

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009
Takeshi Aoki
Abstract The photoluminescence (PL) emission band corresponding to 4F3/2,4I15/2 transition has been revealed using a double lock-in technique and quadrature frequency resolved spectroscopy (QFRS) at room temperature in Nd3+ in a GaLaS glass. The band is centred around 1840 nm and has a lifetime ,77 ,s, which seems to be the same for all four radiative transitions 4F3/2,4IJ (J = 9/2, 11/2, 13/2 and 15/2). The branching ratios ,J of the four above transitions have been estimated from the PL data and agree well with the results of Judd-Ofelt (JO) analysis. In addition to the 1840 nm band, we have observed another PL band appearing around 1580 nm and having a dominant lifetime ,3.8 ,s. This band may be identified with the radiative transition from the doublet (4F5/2, 2H9/2) to the 4I15/2 manifold. The short lifetime ,3.8 ,s may be caused by effective multiphonon relaxation from the doublet to the 4F3/2 manifold. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]