Researchers from China have created a novel 3D printing method that takes advantage of what they call ‘molecular glue’ that allows engineers to print precise, high-quality structures, such as semiconductors.
Developed by a research unit from Beijing’s Tsinghua University and published in the peer-reviewed scientific journal, Science, the technique, dubbed 3D pinning, could facilitate the creation of numerous hi-tech designs, including high-performance, cost-effective semiconductors.
3D-printing semiconductors typically involve bonding layers of materials like copper, graphene or carbon, with a polymer agent. How well the semiconductor performs depends on the integrity of the bond, as the inclusion of polymers in the semiconductor mix alters the inherent characteristics of the semiconductor material.
To improve upon this, Tsinghua University associate professor, Zhang Hao, and his colleagues, professors Lin Linhan, Li Jinghong and Sun Hongbo, set out to create the world’s first 3D-printed semiconductor featuring nanometre-level structures.
The team’s work marks the first time semiconductors or inorganic functional materials have been 3D-printed without polymer bonding at a nanoscale resolution – a breakthrough that could pave the way for significant technological leaps in the relatively new field, according to the South China Morning Post.
The absence of a binding agent means 3D-printed semiconductors have a significantly higher purity and retain nearly 100 percent of their electromagnetic properties, added the team.
Zhang and his peers first created semiconductor nanocrystals suspended in colloidal ink. The semiconductor mixture was combined with the molecular glue that, when subjected to laser treatment, formed stable bonds throughout the 3D-printed structure.
With the versatile ink formula, the technique could be used to print a variety of structures, including semiconductors, metals, semiconductor oxides and even heterogeneous designs, like mussel shells, that combine different substances, including silicon oxide, calcium carbonate and protein molecules.
Materials printed with Tsinghua University’s 3D pinning method had a significantly higher purity content than standard 3D printing, with a recorded mass fraction of inorganic components of more than 90 percent – this is almost 40 percent higher than traditional printing methods.
Compared to widely used integrated circuit manufacturing methods that can only print two-dimensional structures and then stack the layers to form 3D objects, 3D pinning can achieve an incredibly accurate resolution of 150 nanometres, printing detailed 3D structures like the Eiffel Tower and human faces.
Although their method is highly efficient and could be a cost-effective alternative for the production of 3D-printed semiconductors, the team says 3D pinning is not necessarily a direct replacement for standard techniques. Rather it should be seen as something that could supplement the industry, especially where printing 3D designs are required.
Because 3D pinning is nanometre-accurate, it is an excellent candidate for the production of quantum dots, some of the most minute components present in nanotechnology. These dots are used in several medical applications, such as tissue engineering and theranostics, and can be found in many modern LED televisions and solar panels.
Zhang and his team’s next goal is to refine their method to hopefully reach a purity level closer to 100 percent, as well as improve the method’s precision and speed.
