Conductive ink is the primary component of all printed electronic devices and circuit boards, creating the basic structure for integrated low-resistance circuits and contact electrodes. However, manufacturing a graphene-based conductive ink with good conductance and distribution stability in water remains a significant difficulty.
Study: Facile Synthesis of Ag/Carbon Quantum Dots/Graphene Composites for Highly Conductive Water-Based Inks. Image Credit: wacomka/Shutterstock.com
A recent study published in the journal ACS Applied Materials & Interfaces focuses on the production of a remarkably conductive silver/carbon quantum dots/graphene (Ag/CQD/G) nanocomposite for manufacturing water-based conductive ink.
What is a Conductive Ink?
Conductive ink is essential in the production of stretchable electronic equipment. A high-performance conductive ink must have exceptional conductance, adherence to the substrate, and durability. Depending on the substance used in its production, the conductive ink can be either metal-based or carbon-based.
Silver nanoparticles are presently the most extensively utilized materials for producing conductive ink because of their great electrical conductance and strong antioxidant characteristics. Silver materials, however, are highly costly, and silver diffusion is a severe problem that seriously affects the dependability of silver tracks.
Copper-based conductive ink is less costly and simpler to produce than silver-based conductive ink. However, it oxidizes readily, restricting its industrial applicability.
Conductive ink, made up of carbon-based nanostructures such as graphene, carbon nanotubes, carbon nanofibers, and carbon black, can solve the challenges listed above and has attracted much interest due to its excellent mechanical and electrical characteristics.
Graphene-Based Conductive Ink: Applications and Limitations
Graphene is a highly promising carbon nanostructure for manufacturing conductive ink with conductance equivalent to silver ink. Furthermore, graphene-based conductive ink provides several benefits, including cheap cost, high stability, and broad application.
As a result, the creation of high-performance graphene-based ink can aid in advancing printed microelectronics.
Water-soluble graphene oxide (GO) is often employed as a raw ingredient for manufacturing graphene-based conductive ink due to its inexpensive cost and strong water degradability. However, converting pre-printed GO patterns to conducting patterns involves high temperatures and powerful reducing chemicals, restricting their use in wearable electronic devices.
Graphene nanosheets with pristine properties have better electrical characteristics than rGO. However, they tend to agglomerate due to pi-pi stacking and van der Waals contacts, making them challenging to employ in most solvents.
Improving Conductivity of Graphene-Based Inks
From an economical and ecological standpoint, it is critical to produce graphene-based nanomaterials with high conductance and strong dispersibility in water that are cost-effective, non-toxic, and durable under normal conditions.
Different agents and hydrophilic materials, such as polyvinyl pyrrolidone and polyethyleneimine ethoxylated, have been observed to increase graphene solubility and durability in water-based solvents. However, these dispersion chemicals are difficult to remove entirely, resulting in poor conductance composites and environmental contamination.
Carbon quantum dots (CQDs), which are amphiphilic semiconductors, can be deposited on the surface of graphene and dramatically increase its conductance and solubility in water.
Another feasible method for increasing the conductance of graphene-based conductive ink is to coat it with metal nanoparticles (NPs). Many silver (Ag) nanoparticles with various morphologies operate as nanoscale connections between graphene sheets, resulting in Ag/graphene composites with low contact resistance and increased capability for manufacturing a highly conductive ink.
Highlights and Key Developments of the Study
In this study, the researchers created a unique Ag/CQDs/G composite by in-situ photo-reduction of silver nitrate and layering silver onto graphene nanosheets to produce a highly conductive ink.
This is a simple and uncomplicated method for preparing Ag/CQDs/G composites, eliminating the need to reduce chemicals or high-temperature reduction procedures.
The as-prepared Ag/CQDs/G nanocomposite demonstrated high dispersibility and durability in water for 30 days. The introduction of Ag NPs to the Ag/CQDs/G nanocomposite resulted in a 97.2 percent drop in electrical resistance compared to simple graphene sheets. In addition, the produced Ag/ CQDs/G patterns had a low contact resistivity following rolling compression.
The as-prepared nanocomposite is a suitable filler for producing water-based conductive ink because of its strong water dispersibility and high electrical conductance. Furthermore, after 5000 bending cycles, the printed patterns demonstrated exceptional structural stability, paving the way for producing a range of high-performance adaptable electronic products, such as circuit boards and radio-frequency identification devices (RFIDs).
Gao, C. et al. (2022). Facile Synthesis of Ag/Carbon Quantum Dots/Graphene Composites for Highly Conductive Water-Based Inks. ACS Applied Materials & Interfaces. Available at: https://pubs.acs.org/doi/10.1021/acsami.2c06298