64 research outputs found
One-step Preparation of ZnO Electron Transport Layers Functionalized with Benzoic Acid Derivatives
We present a "one-step" approach to modify ZnO electron transport layers
(ETLs) used in organic solar cells. This approach involves adding benzoic acid
(BZA) derivatives directly to the ZnO precursor solution, which are then
present at the surface of the resulting ZnO film. We demonstrate this approach
for three different BZA derivatives, namely benzoic acid, chlorobenzoic acid,
and 4-hydrazinobenzoic acid. For all molecules, improved device performance and
stability is demonstrated in solar cells using an active layer blend of PTQ10
(donor) and ITIC-Br (non-fullerene acceptor) compared to such cells prepared
using untreated ZnO. Furthermore, similar or improved device performance and
stability is demonstrated compared to conventional PEIE treatment of ZnO. The
presence of the BZA derivatives at the surface after processing is established
using X-ray photoelectron spectroscopy and near-edge X-ray absorption
fine-structure spectroscopy. From atomic force microscopy analysis and X-ray
diffraction studies, the addition of BZA derivatives appears to restrict ZnO
grain growth; however, this does not negatively impact device performance. ZnO
layers treated with BZA derivatives also exhibit higher water contact angle and
lower work function compared to untreated ZnO. This approach enables
simplification of device manufacture while still allowing optimization of the
surface properties of metal oxide ETLs. Keywords: electron transport layers,
zinc oxide, organic solar cells, surface modificationComment: Manuscript: 25 pages, 8 figures, 5 tables. Supplementary Material: 36
pages, 22 figures, 13 tables. Submitted to Solar Energy Materials and Solar
Cell
Polyolefin composition for medium/high/extra high voltage cables comprising benzil-type voltage stabiliser
The present invention relates to a polyolefin composition comprising (A) a polyolefin, (B) a benzil derivative comprising, preferably consisting of, the structural unit according to the following formula (I) wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 independently from each other are hydrogen, or a hydrocarbyl group which may contain heteroatoms or at least two of said R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 together with the ring atoms of the ring system of formula (I) they are attached to, form a further aromatic or non-aromatic ring fused to the ring system of formula (I) and at least R1 or R2 is an ester group. The invention also relates to a wire or cable, in particular a medium, high or extra high voltage cable, comprising such a composition, and to the use of such a composition for the production of a wire or cable, in particular a medium, high or extra high voltage cable
Study of the possibility to measure the root-mean-square roughness of a shaded rough surface
Thioxanthone Derivatives as Stabilizers Against Electrical Breakdown in Cross-Linked Polyethylene for High Voltage Cable Applications
In the search of voltage stabilizers for high voltage underground cables the chemical synthesis and electrical tree inhibiting effect of a series of thioxanthone derivatives in cross-linked low-density polyethylene (XLPE) is reported. The strongest increase in electrical tree initiation field under high-voltage alternating current (HVAC) conditions was 55% compared to reference XLPE after the addition of 0.3 wt% 9-oxo-9H-thioxanthen-2-yl methacrylate. Thermal analysis, small angle X-ray scattering and gel content measurements showed that the addition of the stabilizers did not significantly influence the microstructure and gel fraction of XLPE. A comparison between the stabilizing effects of the thioxanthone derivatives and previously reported photophysical properties revealed that a short lifetime of the triplet excited state can be related to a good voltage-stabilizing effect
Tailored Side-Chain Architecture of Benzil Voltage Stabilizers for Enhanced Dielectric Strength of Cross-Linked Polyethylene
The synthesis and physico-chemical properties of seven benzil-type voltage stabilizers are reported. The benzil core is substituted with alkyl chains of different length that are linked to the benzil core via an ester, ether, or tertiary amine group. All additives can be melt-processed with low-density polyethylene (LDPE). Fourier-transform infrared spectroscopy confirms that benzil compounds are not affected by the LDPE cross-linking reaction induced by dicumyl peroxide. Moreover, a combination of gel content measurements, thermal analysis, and small-angle X-ray scattering indicates that the presence of benzil voltage stabilizers does not significantly alter the microstructure of cross-linked polyethylene (XLPE). Electrical tree inhibition experiments under high-voltage alternating current conditions show that all investigated additives substantially enhance the dielectric strength of the insulating material at a concentration of only 10 mmol kg−1. The highest improvement in dielectric strength, of more than 70% with respect to reference XLPE, is obtained with voltage stabilizers, which carry short (methyl) side chains that are linked to the benzil core via an ester or tertiary amine group
Reassessing the significance of reduced aggregation and crystallinity of Naphthalene diimide-based copolymer acceptors in all-polymer solar cells
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