Princeton team prints quantum dot LEDs
3D printing has so far been limited to specific plastics, passive conductors, and a few biological materials. But a team at Princeton has now successfully printed quantum dot-based LEDs, showing that diverse classes of materials can be 3D printed and fully integrated into devices with active properties.
In their report in Nano Letters, the researchers describe the seamless interweaving of five different materials: emissive semiconducting inorganic nanoparticles; an elastomeric matrix; organic polymers as charge transport layers; solid and liquid metal leads, and a UV-adhesive transparent substrate layer.
Having produced 3D printed quantum dot-based LEDs (based on CdSe nanoparticles wrapped in ZnS with a top layer of GaIn) as a proof of concept, they went on to show that it was possible to conformally print the LEDs onto curved surfaces, such as contact lenses.
A third example described in the paper was a 2x 2x 2 cube of encapsulated LEDs, in which every component of the cube and electronics was 3D printed. This was to demonstrate that 3D printing can make novel architectures not easily achieved using standard microfabrication techniques.
Overall, the team says that the results suggest that 3D printing is more versatile than has been demonstrated to date and is capable of integrating many distinct classes of materials.
"˜3D Printed Quantum Dot Light-Emitting Diodes' by Y. L. Kong et al, appears in Nano Lett. (2014). DOI: 10.1021/nl5033292