Largely Enhanced Surface Flashover Voltage of Poly(ether Imide) by Scalable and Durable ZnO Coating: A Gift from In Situ Growth

Abstract

Dielectric materials with high surface electric insulation strength are in great demand in a high-power space solar cell array (SSCA). A moderately conductive surface is favorable to inhibit charge accumulation and mitigate electric field distortion, thus improving the surface flashover voltage. Although numerous modification methods have been proposed to achieve this goal, the facile, efficient, scalable, and environmentally friendly modification strategy remains a critical challenge to date. Considering the excellent charge modulation ability of ZnO and its mild preparation conditions, a facile and economical hydrothermal strategy was proposed to fabricate in situ a durable poly­(ether imide)/zinc oxide (PEI/ZnO) coating with a high charge decay rate. The blooming flower-like ZnO in the coating is proved to play a key role in enhancing lateral charge dissipation on the surface of PEI, thereby suppressing surface charge accumulation. It was also shown that the shielding effect of ZnO on high-energy photons during flashover and the catalytic effect of Zn2+ on PEI molecular chains during hydrothermal treatment had a facilitating and suppressing effect on outgassing, respectively, and consequently affected the flashover. Excitingly, the synergistic effects of both accelerated charge dissipation and suppressed outgassing helped to improve the flashover voltage of PEI by up to 36.7%. The strategy selected here is efficient, scalable, and facile, and the coating is durable, which makes sense for commercial promotion.

Customizing superior surface insulation properties of polymeric dielectric via in-plane molecular chain orientation

“…Surface flashover, a ubiquitous surface electrical breakdown phenomenon that occurs at the interface of vacuum and dielectric surface, is usually triggered before the bulk breakdown of both vacuum and solid. Poor surface insulation property often leads to premature surface flashover, which has been the main factor severely constraining the operating voltage and durability of vacuum devices [1][2][3][4]. Clarifying the underlying mechanism of surface flashover and developing targeted methods * Authors to whom any correspondence should be addressed.…”

“…This is because the reverse electric field formed by the accumulated charge can further inhibit primary charge injecting from cathode triple junction. However, it must be noted that when charge migration properties are changed by such mentioned composition-modulated modification methods, it is likely that other flashover-related factors are also changed [2,4,8]. Hence, the improvement of surface insulation strength shows variability and poor controllability.…”