Chemically doped three-dimensional porous graphene monoliths for high-performance flexible field emitters

Abstract

Despite the recent progress in the fabrication of field emitters based on graphene nanosheets, their morphological and electrical properties, which affect their degree of field enhancement as well as the electron tunnelling barrier height, should be controlled to allow for better field-emission properties. Here we report a method that allows the synthesis of graphene-based emitters with a high field-enhancement factor and a low work function. The method involves forming monolithic three-dimensional (3D) graphene structures by freeze-drying of a highly concentrated graphene paste and subsequent work-function engineering by chemical doping. Graphene structures with vertically aligned edges were successfully fabricated by the freeze-drying process. Furthermore, their number density could be controlled by varying the composition of the graphene paste. Al- and Au-doped 3D graphene emitters were fabricated by introducing the corresponding dopant solutions into the graphene sheets. The resulting field-emission characteristics of the resulting emitters are discussed. The synthesized 3D graphene emitters were highly flexible, maintaining their field-emission properties even when bent at large angles. This is attributed to the high crystallinity and emitter density and good chemical stability of the 3D graphene emitters, as well as to the strong interactions between the 3D graphene emitters and the substrate.

Electron Emission Devices for Energy‐Efficient Systems

“…It can be used as a tool to achieve enhanced emission current at lower electric field thresholds. Some of the recently used dopants are metals and metal oxides including Au, Pt, Al, Cu, In, boron, carbon, graphdiyne, silicon, lithium, nitrogen, and tin sulfide . In this context, introducing oxygen vacancy doping for enhanced field emission is gaining significant interest in recent years due to its easy processing.…”

“…c) Effect of gold (Au) and aluminium (Al) doping on field emission of reduced‐graphene oxide (rGO). Reproduced with permission . Copyright 2015, Royal Society of Chemistry.…”

Structure, Mechanical and Electrochemical Properties of Thermally Reduced Graphene Oxide-poly (Vinyl Alcohol) Foams

“…It is believed that three dimension (3D) graphene architecture, similar to a foam, will further expand its significance in various applications [6,7], such as electronic devices including supercapacitor, lithium-ion batteries, fuel cells, dye-sensitized solar cells, electrochemical sensors, environmental clean-up and biomedical equipments [8][9][10]. For example, 3D graphene architecture with different pore sizes from sub-micrometre to several micrometres was obtained by Kim et al [11] and exhibited excellent electrochemical performance due to the high-rate transportation network of the electrolyte ions and multidimensional electron transport pathways for a high performance field emitter.…”

Laser-Patternable Graphene Field Emitters for Plasma Displays

“…However, a requirement for the graphene utilized in field electron emission devices is that the material should be vertically aligned/protrude from the polymer substrate, providing more individual field emission sites, as flat graphene sheets lack sharp edges and require a high voltage to turn on the FEE process [10]. Several methods for synthesizing graphene nanostructures on polymer substrates, such as spin-casting, electrophoresis, self-assembly, thermal welding, and filtering, have been developed and have employed the obtained nanostructures as efficient field emitters [11,12,13,14,15,16]. A cost-effective process of synthesizing graphene nanostructures on polymers using cheap precursors is needed for the industrial production of display devices.…”