High electron affinity: a guiding criterion for voltage stabilizer design

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 E HOMO -E LUMO 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 E HOMO -E LUMO 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.

Functional design of epoxy-based networks: tailoring advanced dielectrics for next-generation energy systems

“…In this work, the increased breakdown strength was suggested to be due to two factors namely, the difference between the ionisation potential of the added aromatic-alkyl molecules compared to that of the host material and the high electron affinity of such structures, which would allow aromatic-alkyl moieties to act as voltage stabilizers within the system. 56,57 While we are not aware of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d M a n u s c r i p t any theoretical studies of charge transport through epoxy resins, this is not the case for analogues of polyethylene, where the role of both chemical and structural factors have been considered 24,[58][59][60] . In the latter case, the importance of free volume on electron transport has been demonstrated and, therefore, in addition to the direct role of the functional groups of the FNM, the impact of such species on local structure and, thereby, charge transport dynamics may also be significant.…”

Enhancement of Service Life and Electrical Insulation Properties of Polymeric Cables With the Optimum Content of Aromatic Voltage Stabilizer

“…It should be noted here that the irrespective of the wt% of the voltage stabilizer, the trap energy level and trap density are increased. This is attributed to the electron affinity of the voltage stabilizers . The effect of the traps and the material properties on the electrical measurements is discussed in the following section.…”

Investigation of the Space Charge and DC Breakdown Behavior of XLPE/α-Al2O3 Nanocomposites

“…This may have been because the insulating coated α-Al 2 O 3 nanosheets were intrinsic electrical insulating nanopaticles [37]. Secondly, the redistribution of space charge in the insulation material causes electric field homogenization and decreases the free volume of XLPE [38].…”

“…This may have been because the insulating coated α-Al2O3 nanosheets were intrinsic electrical insulating nanopaticles [37]. Secondly, the redistribution of space charge in the insulation material causes electric field homogenization and decreases the free volume of XLPE [38]. More importantly, flaky Al2O3 has a blocking effect on the transport of injected charge along the thickness direction just as shown in Figure 9; the charge transport through the flakes becomes inhibited with a detour effect.…”