Three-dimensional printing technology is constantly evolving. Some people believe that in the near future 3D-printers will be able to compete with production companies, giving them the course in the performance, but dramatically outperforming them in the customization of the final product. A significant limitation for existing devices is that they work with monomaterial. Michael McAlpine, a professor at Princeton University, an expert in mechanical engineering, he decided to change the situation. He and his team managed to print the 3D-printer LED current with multilevel structure of the crystal. Six months of hard work in university laboratories and from $ 10,000 to $ 20,000 cost it took to create a three-dimensional printer that can print a crystal of 5 layers of dissimilar metals and polymers.
The output of the innovators got a fully functional LED Spot similar to those used for LED-backlight monitor TVs and smartphones. The contact layer is formed as a ring of silver nanoparticles. It is located in the substrate formed by two ultrathin layers of complex polymer (PEDOT: PSS, and Poly-TPD). Anode-hole quantum layer is implemented as a film of cadmium selenide, CdSe cores in a coating of zinc sulfide ZnS. In this layer are emitted photons of light when bombarded with electrons holes. The upper (cathode) layer of the LED is made of eutectic alloy of gallium indium.
MacAlpin, describing the outcome, stresses that the resulting LED is the first object in the world printed on a 3D-printer and containing so many completely different materials in a single object. In progress, researchers are not going to stop. The next objective of the team of Princeton University — to teach 3D-printer prints a fully functional semiconductor transistors.