Semiconductors are essential for all modern electronics.
Now, researchers at Linköping University in Sweden have developed a new method to make organic semiconductors more conductive using air as a dopant.
This study, published in the journal Nature, is a big step towards creating cheap and sustainable organic semiconductors.
“We believe this method could greatly change how we dope organic semiconductors.
All the components are affordable, easily accessible, and potentially environmentally friendly, which is important for future sustainable electronics,” says Simone Fabiano, associate professor at Linköping University.
Organic semiconductors, which are made from conductive plastics instead of silicon, have many potential uses. They can be used in digital displays, solar cells, LEDs, sensors, implants, and energy storage devices.
To improve conductivity and change the properties of semiconductors, special additives called dopants are typically added.
These dopants help electrical charges move within the semiconductor material and can be designed to add either positive (p-doping) or negative (n-doping) charges.
However, the most common dopants used today are often very reactive (unstable), expensive, or difficult to manufacture.
Now, researchers at Linköping University have developed a doping method that works at room temperature, using oxygen as the main dopant and light to activate the process.
“Our approach was inspired by nature, similar to photosynthesis. In our method, light activates a photocatalyst, which then helps transfer electrons from a typically weak dopant to the organic semiconductor material,” says Fabiano.
The new method involves dipping the conductive plastic into a special salt solution—a photocatalyst—and then shining light on it for a short time. The amount of light exposure determines how much the material is doped.
Afterward, the solution can be reused, leaving behind a p-doped conductive plastic where the only substance consumed is oxygen from the air.
This works because the photocatalyst acts as an “electron shuttle,” taking or donating electrons to the material in the presence of weak oxidants or reductants. While common in chemistry, this has not been used in organic electronics before.
“It’s also possible to combine p-doping and n-doping in the same reaction, which is unique. This simplifies the production of electronic devices that need both types of semiconductors, like thermoelectric generators,” says Fabiano.
With this new method, all parts can be manufactured and doped simultaneously, making the process more scalable.
The doped organic semiconductor has better conductivity than traditional semiconductors, and the process can be scaled up.
Fabiano and his research group at the Laboratory of Organic Electronics had already shown earlier in 2024 that conductive plastics could be processed from environmentally friendly solvents like water; this new method is their next step.
“We are just beginning to understand the mechanism behind this and exploring other potential applications. But it’s a very promising approach that shows photocatalytic doping could become a new cornerstone in organic electronics,” says Fabiano, a Wallenberg Academy Fellow.
Source: Linköping University.
