| 1. |
- Gray, Victor, 1988, et al.
(författare)
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Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet-triplet annihilation photon upconversion
- 2015
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 3:42, s. 11111-11121
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Tidskriftsartikel (refereegranskat)abstract
- Molecules based on anthracene are commonly used in applications such as OLEDs and triplet-triplet annihilation upconversion. In future design of blue emitting materials it is useful to know which part of the molecule can be altered in order to obtain new physical properties without losing the inherent optical properties. We have studied the effect of substitution of 9,10-substituted anthracenes. Eight anthracenes with aromatic phenyl and thiophene substituents were synthesised, containing both electron donating and accepting groups. The substitutions were found to affect the UV/Vis absorption only to a small extent, however the fluorescence properties were more affected with the thiophene substituents that decreased the fluorescence quantum yield from unity to
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| 2. |
- Jarvid, Markus, 1985, et al.
(författare)
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High electron affinity: a guiding criterion for voltage stabilizer design
- 2015
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 3:14, s. 7273-7286
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Tidskriftsartikel (refereegranskat)abstract
- Voltage stabilizers are an emerging class of additives that enhance the dielectric strength of an insulating polymer such as polyethylene. Several partially conflicting reports ascribe the stabilizing effect to either a high electron affinity or low ionization potential of the additive. Here, we report a clear correlation of the electron affinity and to a lesser extent the EHOMO–ELUMO difference of various voltage stabilizers with electrical tree initiation in cross-linked polyethylene. To facilitate a fair evaluation, the voltage-stabilizing efficiency of a set of 13 previously reported voltage stabilizers, which strongly differ in their chemical composition, is compared at equal stabilizer concentration and equivalent test methodology. These results are correlated with the electron affinity and EHOMO–ELUMO difference, as obtained from density functional theory (DFT) modeling, which agreed well with available literature values. Moreover, based on the here established strong correlation between dielectric strength and electron affinity, a new molecule with exceptionally high electron affinity is selected from the extended literature on organic photovoltaics. This malononitrile–benzothiadiazole–triarylamine based molecule with a high electron affinity of 3.4 eV gives rise to a 148% increase in tree initiation field compared to 40% obtained using anthracene, one of the most efficient previously reported voltage-stabilizers, under equivalent test conditions. Thus, we here propose to use the electron affinity as a guiding criterion for identifying novel high-efficiency voltage stabilizers, which opens up the vast library of organic semiconductors as potential candidates, as well as associated synthesis routines for the design of yet unexplored materials.
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| 3. |
- Movahedi, Alireza, 1983, et al.
(författare)
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Cu(i) stabilizing crosslinked polyethyleneimine
- 2015
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 17:28, s. 18327-18337
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Tidskriftsartikel (refereegranskat)abstract
- Polyethyleneimine (PEI) is known for its metal-coordinating properties and in its crosslinked form has applications in different areas ranging from drug delivery to waste water treatment and recovery of trace metals. With the aim to regulate the coordination environment of Cu(i) and Cu(ii) ions in marine coatings, we have prepared a triazole cross-linking agent with 'soft' coordination that can crosslink PEI via indirect reductive amination. We have shown that this triazole crosslinker not only increases the Cu(ii) absorption capacity of the crosslinked PEI in comparison to the traditionally used glutaraldehyde-crosslinked PEI (PEI-GA), but also allows the crosslinked polymer network to stabilize the Cu(i) oxidation state more effectively. The Cu(ii) uptake and Cu(i) stabilization of the polymer have been determined by elemental analysis and UV-vis spectroscopy. It was found that the triazole-crosslinked polymer (PEI-TA) could coordinate up to 12 wt% of Cu(ii) before and 6 wt% Cu(ii) after imine reduction.
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