Reviving the “Schottky” Barrier for Flexible Polymer Dielectrics with a Superior 2D Nanoassembly Coating

Abstract

The organic insulator–metal interface is the most important junction in flexible electronics. The strong band offset of organic insulators over the Fermi level of electrodes should theoretically impart a sufficient impediment for charge injection known as the Schottky barrier. However, defect formation through Anderson localization due to topological disorder in polymers leads to reduced barriers and hence cumbersome devices. A facile nanocoating comprising hundreds of highly oriented organic/inorganic alternating nanolayers is self‐coassembled on the surface of polymer films to revive the Schottky barrier. Carrier injection over the enhanced barrier is further shunted by anisotropic 2D conduction. This new interface engineering strategy allows a significant elevation of the operating field for organic insulators by 45% and a 7× improvement in discharge efficiency for Kapton at 150 °C. This superior 2D nanocoating thus provides a defect‐tolerant approach for effective reviving of the Schottky barrier, one century after its discovery, broadly applicable for flexible electronics.

High-energy-density polymer dielectrics via compositional and structural tailoring for electrical energy storage

“…Therefore, the ideal Schottky barrier is hardly achieved and cannot sufficiently impede the charge injection. At present, macro-interface engineering is a useful strategy to enhance the breakdown strength by nanocoating on polymer films to eliminate surface states, resulting in reviving the injection barrier and promoting lateral dissipation of injected charges ( Zhang et al., 2021 ).…”

Scalable self-assembly interfacial engineering for high-temperature dielectric energy storage

“…Imperfections on the surface of polymer films stemming from complex morphological and conformational disorders of polymers introduce surface defect states, via which charges can inject into the bulk of the film over the lowered energy barrier ( Coelho, 1974 ; Hughes, 1980 ; Kamal et al., 2020 ; Roy et al., 2005 ). Therefore, to explore flexible dielectric materials utilizing established high-temperature polymers, an alternative strategy is to inhibit charge injection from electrodes and thus suppress the conduction current with the interface engineering technique ( Zhang et al., 2021a ). Inorganics with large bandgaps were deposited on polymer film surfaces to block the charge injection, using chemical vapor deposition (CVD) and physical vapor deposition (PVD) typically requiring high-temperature processing, complicated chemical reactions, and/or high voltage plasma assistance ( Azizi et al., 2017 ; Zhou et al., 2018 ).…”

“…We demonstrated a facile flow-induced self-assembly coating approach for re-surface engineering ( Zhang et al., 2021a ). Compared to chemical vapor or physical deposition of inorganics, solution-based coating is economically more scalable and higher throughput ( Zhu et al., 2016 ).…”

Enhancing corona resistance in Kapton with self-assembled two-dimensional montmorillonite nanocoatings

“…21 From a manufacturing point of view, such a nanoclay coating is inexpensive to process and can be applied to a wide range of polymers. 22 Unlike the microlayered polymer films achieved by coextrusion processing, this nanoclay coating can produce extremely high-density ordered organic/inorganic interfaces composed of nanosheets with a thickness of 1 nanometer, which can efficiently enhance the insulation property and long-term stability of the coated polymer films. 23 In this study, to assess the endurance life imparted by such coatings in terms of harsh condition electrical insulation, we fabricated MMT self-assembly coatings on the surfaces of polyimide (PI) film (Kapton s HN), which is widely used in electrical power apparatus and electronics as dielectric coatings for copper wires/conductors, motor slot-liners, flexible circuit substrates, and dielectric thin films and encapsulation layers.…”

“…21 From a manufacturing point of view, such a nanoclay coating is inexpensive to process and can be applied to a wide range of polymers. 22 Unlike the microlayered polymer films achieved by coextrusion processing, this nanoclay coating can produce extremely high-density ordered organic/inorganic interfaces composed of nanosheets with a thickness of 1 nanometer, which can efficiently enhance the insulation property and long-term stability of the coated polymer films. 23…”