TY  - JOUR
A1  - Tomczyk, Jaroslaw
A1  - Sobolewska, Anna
A1  - Nagy, Zsuzsanna T.
A1  - Guillon, Daniel
A1  - Donnio, Bertrand
A1  - Stumpe, Joachim
T1  - Photo- and thermal-processing of azobenzene-containing star-shaped liquid crystals
JF  - Journal of materials chemistry : C, Materials for optical and electronic devices
N2  - A new class of star-shaped, liquid crystalline, low-molecular weight compounds functionalized with photochromic azobenzene and mesogenic groups was investigated in terms of light-induced anisotropy. The behaviour of the materials under the action of light with simultaneous or subsequent thermal treatment was examined with respect to the induction of anisotropy. The unconventional UV light treatment prior to the irradiation with linearly polarized light allowed induction of very high values of anisotropy (D = 0.77) at room temperature. Moreover, the simultaneous action of light and temperature led to the induction of higher values of dichroism in comparison with anisotropy generated by the standard procedure. Subsequent thermal treatment led to dewetting and the formation of 3D macroscopic stripe- and dome-like structures for one of the investigated compounds. Despite photoinduction of anisotropy by a single beam, the formation of polarization and surface relief gratings by two-beam interference pattern was also investigated.
Y1  - 2013
U6  - https://doi.org/10.1039/c2tc00627h
SN  - 2050-7526
VL  - 1
IS  - 5
SP  - 924
EP  - 932
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Heydari, Esmaeil
A1  - Pastoriza-Santos, Isabel
A1  - Flehr, Roman
A1  - Liz-Marzan, Luis M.
A1  - Stumpe, Joachim
T1  - Nanoplasmonic enhancement of the emission of semiconductor polymer composites
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - We report on the influence of localized surface plasmon resonance excitation of Au@SiO2 core-shell nanoparticles on the amplified spontaneous emission of a semiconductor polymer composite (F8BT/MEH-PPV). Au@SiO2 nanoparticles are compatible with the donor-acceptor polymer matrix and get uniformly distributed within the whole polymer film. The plasmon resonance band of the nanoparticles correlates with both the emission and excitation spectra of the polymer composite, as well as with the donor emission and acceptor excitation spectra. We demonstrate that resonantly excited Au@SiO2 nanoparticles enhance the amplified spontaneous emission and the modal gain of the polymer films. The measurement of influential factors reveals that the emission is enhanced predominantly by the increase of acceptor excitation rate, which is accompanied by depletion of the FRET efficiency and increase of quantum yield. The enhancement factor is increased by both introducing a higher loading of plasmonic nanoparticles in the polymer film and increasing the excitation energy. This work shows that these plasmonic nanoantennas are able to enhance the stimulated emission of semiconductor polymers by improving the size mismatch between the excitation light and the emitting polymer.
Y1  - 2013
U6  - https://doi.org/10.1021/jp404068m
SN  - 1932-7447
VL  - 117
IS  - 32
SP  - 16577
EP  - 16583
PB  - American Chemical Society
CY  - Washington
ER  -