In this work, we present an experimental setup for the in situ and ex situ study of the optical activity of samples, which can be prepared under ultra‐high vacuum (UHV) conditions by second‐harmonic generation circular dichroism (SHG‐CD) over a broad spectral range. The use of a racemic mixture as a qualified reference for the anisotropy factor is described and, as an example, the chiroptical properties of 1.5 μm thick (multilayers) as well as sub‐monolayer thin films of the R‐ and S‐enantiomer of 1,1′‐Bi‐2‐naphthol (BINOL) evaporated onto BK7 substrates were investigated.
The
performance of semiconducting polymers strongly depends on
their intra- and intermolecular electronic interactions. Therefore,
the morphology and particularly crystallinity and crystal structure
play a crucial role in enabling a sufficient overlap between the orbitals
of neighboring polymers. A new solution-based in situ polymerization
for the fabrication of native polythiophene thin films is presented,
which exploits the film formation process to influence the polymer
crystal structure in the resulting thin films. The synthesis of the
insoluble polythiophene is based on an oxidative reaction in which
the oxidizing agent, iron(III)
p
-toluenesulfonate
(FeTos), initially oxidizes the monomers to enable the polymer chain
growth and secondly the final polymers, thereby chemically doping
the polythiophene. To exploit the fact that the doped polythiophene
has a different crystal packing structure compared to the undoped
polythiophene, we investigate the structural effect of this inherent
doping process by varying the amounts of FeTos in the reaction mixture,
creating polythiophene thin films with different degrees of doping.
The structural investigation performed by means of grazing incidence
wide-angle X-ray scattering (GIWAXS) suggests that the strongly doped
polymer chains aggregate in a π-stacked manner in the film formation
process. Moreover, this π-stacking can be maintained after the
removal of the dopant molecules. GIWAXS measurements, molecular dynamics
simulations, and spectroscopic analysis suggest the presence of polythiophene
in a novel and stable crystal structure with an enhanced intermolecular
interaction.
In this work, we apply supported ionic liquid phase (SILP) catalysts to hydrogenate 1-alkenes in a continuous fixed-bed reactor. SILP catalyts were prepared using the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide...
The use of multilayer, solution‐processed organic thin film devices can benefit strongly from the controlled deposition of insoluble thin films. Here, a solution‐based in situ polymerization technique for semiconducting polythiophene thin films based on nonchlorinated solvents forming a range of large‐scale structured or homogeneous, insoluble thin films is systematically developed. The high‐quality nature of the resulting polythiophene thin films is demonstrated by successfully implementing the films in the active layer of bilayer heterojunction solar cells. It is possible to transfer this protocol to large‐scale processing without additional changes to the material system.
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