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Researchers Boost Flexible Electronics Sustainability With Water-Based Inks

February 09, 2024 by Jake Hertz

The team leveraged ground-state electron transfer to develop water-based conductive ink for use in flexible electronics.

A major trend in electronics has been the emergence of flexible electronics in devices such as solar cells and energy storage. The technology enabling these devices to be flexible and lightweight is organic electronics. However, concerns about the sustainability of producing organic electronics are growing.

Recently, researchers in Sweden tackled the sustainability challenges head-on by developing water-based conductive inks in organic electronics. 

 

Flexible solar panel for military use.

Flexible solar panel for military use. Image used courtesy of NASA

 

Organic Electronics Challenges

Organic electronics use conductive polymers and carbon-based compounds. These materials make organic electronics lightweight and flexible and can be manufactured at lower costs than traditional electronics. 

However, the environmental impact of producing organic electronics may impede their widespread development and adoption. The processing of conjugated polymers often requires using environmentally hazardous, toxic, and flammable solvents. This reliance on harmful chemicals poses significant obstacles to the sustainable and environmentally responsible manufacturing of organic electronic devices. The toxicity and volatility of these solvents present environmental hazards and health risks to those involved in the manufacturing process.

 

Conjugated polymers are a key part of organic electronics

Conjugated polymers are a key part of organic electronics. Image used courtesy of Wang et al.

 

Additionally, factors such as lower electrical conductivity can limit the performance of organic electronic devices compared to traditional inorganic materials. Overcoming these performance limitations while maintaining organic electronics's environmental and cost benefits is a key area of ongoing research and development.

 

Water-Insoluble Conductive Inks

To solve sustainability challenges facing the use of conjugated polymers in organic electronics, a research team recently developed an innovative approach for processing water-insoluble conjugated polymers in an environmentally friendly manner. 

The team’s technique hinges on the principle of ground-state electron transfer (GSET) between donor and acceptor polymers. They discovered when a water-soluble donor polymer is mixed with a high-electron-affinity, water-insoluble acceptor polymer, spontaneous GSET occurs. This phenomenon significantly enhances the dispersion of the acceptor polymer in water.

 

The structure and J-V curve of the organic solar cell based on waterborne conductive films.

The structure and J-V curve of the organic solar cell based on waterborne conductive films. Image used courtesy of Liu et al.

 

The team's methodology led to the formation of macromolecular charge-transfer salts. These salts exhibited remarkable improvements in electrical conductivity and stability compared to their pristine polymer counterparts. Specifically, the resultant waterborne conductive films demonstrated electrical conductivity 10,000 times that of pristine polymers. 

Further cementing the importance of their discovery, the researchers applied these water-processable conductive inks to the fabrication of devices, including organic solar cells. The resulting device performed remarkably well, with efficiencies of 16.03% and the ability to retain ~90% of its performance after 123 hours of continuous use. 

 

A More Sustainable Future for Organic Electronics

The research has potential to facilitate the broader adoption and sustainable development of organic electronics. By enabling the eco-friendly processing of conjugated polymers, this study paves the way for more sustainable manufacturing practices in the electronics sector. It represents a significant stride toward mitigating the environmental impact of electronic device production and, hence, knocks down some barriers to the widespread adoption of organic electronics.