3D nanoprinting using semiconductor quantum dots to create optoelectric materials

Principle of operation of the PEB. (A) Schematic illustration showing 3D nano-printing of CdSe / ZnS QD with MPA cap using PEB. (B) Schematic illustration showing the mechanism behind the PEB. (C) FTIR spectra of drop-cast QDs and printed structure. Credit: Science (2022). DOI: 10.1126 / science.abo5345

A team of researchers from Tsinghua University, in collaboration with a colleague from Jilin University, has developed a new 3D nano-printing technique that uses semiconductor quantum dots. In their article published in the journal Science, the group describes their new technique and provides examples of resulting 3D objects. Jia-Ahn Pan and Dmitri Talapin with the University of Chicago provide a piece of Perspective in the same journal issue regarding the more versatile 3D printing devices and the team’s work on this new endeavor.

The use of 3D printing to make three-dimensional objects has greatly expanded over the past decade, leading to new products and faster ways to create demonstration objects. But, as the researchers note with this new effort, 3D printers mostly use polymer-based materials, limiting the type of products that can be made. Manufacturers say they would buy 3D printers that can print products with optical or electronic properties. In this new effort, researchers in China have taken a big step in that direction.

The new method involves using semiconductor quantum dots (nanocrystals made of cadmium selenide, coated with zinc sulfide and with caps made of 3-mercaptopropionic acid binders) as additions to the print material. The points are activated by a laser. Photons from the laser are absorbed by a nanocrystal, resulting in a change in chemistry that allows for bonding between quantum dots, a process known as two-photon absorption. In their configuration, the absorption of protons was possible only in places where the intensity of the light was maximum. This made it possible to create bonds smaller than the wavelength of light.

The researchers note that their technique preserves the optoelectronic properties of quantum dots, which means that 3D printed products using the ink made from them can be used in optoelectronic devices.

The researchers demonstrated the robustness of their ideas by building a 3D printer capable of absorbing two photons and then using it to create several objects, some of which were light-emitting university badges. They also showed that it could be used with a variety of materials.

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