Carbon Allotropes as ITO Electrode Replacement Materials in Liquid Crystal Devices

Abstract

Indium tin oxide (ITO)-free optoelectronic devices have been discussed for a number of years in the light of a possible indium shortage as demand rises. In particular, this is due to the largely increased number of flat panel displays and especially liquid crystal displays (LCDs) being produced for home entertainment TV and mobile technologies. While a shortage of primary indium seems far on the horizon, nevertheless, recycling has become an important issue, as has the development of ITO-free electrode materials, especially for flexible liquid crystal devices. The main contenders for new electrode technologies are discussed with an emphasis placed on carbon-based materials for LCDs, including composite approaches. At present, these already fulfil the technical specifications demanded from ITO with respect to transmittance and sheet resistance, albeit not in relation to cost and large-scale production. Advantages and disadvantages of ITO-free technologies are discussed, with application examples given. An outlook into the future suggests no immediate transition to carbon-based electrodes in the area of LCDs, while this may change in the future once flexible displays and environmentally friendly smart window solutions or energy harvesting building coverings become available.

Evaluating carbon-electrode dielectrophoresis under the ASSURED criteria

“…The typical fabrication method for carbonDEP relies on the carbonization of a patterned organic precursor to form glasslike carbon, which is an allotrope of carbon (24). Although the electrical conductivity of glass-like carbon depends on the carbonization process, usual values reported hover around 1 × 10 −4 Ω/m (25), which is a few orders of magnitudes less than the ideal conductor but similar to indium tin oxide (26,27). Such electrical conductivity allows implemention of DEP forces with a relatively low voltage (<20 Vpp), when the spacing between electrodes is in the order of tens of micrometers.…”

Fabrication of dual-functional electrochromic smart window based on low-cost hybrid transparent electrode coated with a solution-processable polymer

“…37 Thus, strategically bringing down the electrode cost while maintaining an uncompromised device performance is much desired. In this context, attempts are observed in the literature to design costeffective alternative TCEs, such as silver or copper nanowires, [38][39][40][41][42][43][44] graphene, [45][46][47] carbon nanotubes, 46,47 aluminiumdoped zinc oxide (AZO), 48,49 and conducting polymers. 50 However, the process complexity, low stability, high sheet resistance, inhomogeneous electric eld distribution and low transparency limit their application in EC smart window fabrication.…”

Substrate Dependent Charge Transfer Kinetics at the Solid/Liquid Interface of Carbon‐Based Electrodes with Potential Application for Organic Na‐Ion Batteries

“…[27] Carbon materials derived from biomass are widely applied in bioelectrochemical systems, [28][29][30] biosensing applications, [31] and ITO electrode replacement. [32] Additionally, their high electrical conductivity and overall stability during cycling, makes carbon based materials suitable for rechargeable electrochemical power sources, such as batteries, including stationary and large-scale systems, [10,33,34] supercapacitors, [35,36] Na-ion batteries, [37][38][39] and Na-ion capacitors. [40] For all these applications, an efficient charge transfer at the materials interfaces (solid/solid or solid/liquid) is crucial and found to be ideal for applications in combination with organic semiconductors (OSCs).…”

“…Among a multitude of applications one finds that carbon based nanomaterials are used to overcome intrinsic limitations in solar cells based on carbon nanomaterials, [19–23] and are heavily used as either active components or supports in electrocatalysis, [24–26] and fuel cells [27] . Carbon materials derived from biomass are widely applied in bioelectrochemical systems, [28–30] biosensing applications, [31] and ITO electrode replacement [32] . Additionally, their high electrical conductivity and overall stability during cycling, makes carbon based materials suitable for rechargeable electrochemical power sources, such as batteries, including stationary and large‐scale systems, [10,33,34] supercapacitors, [35,36] Na‐ion batteries, [37–39] and Na‐ion capacitors [40] .…”