Researchers led by Assistant Professor Michael McAlpine at Princeton University have fabricated the world's first fully 3D printed light-emitting diodes. The process involves interweaving printable electrodes, polymers, and semiconductors, all of which are suspended in solvents to prevent the materials from bleeding into each other, during the printing process. The technology could be used to make smart contact lenses, electronics-embedded implants, and much more.
"To date, 3D printing has been limited to specific plastics, passive conductors, and a few biological materials. Here, we show that diverse classes of materials can be 3D printed and fully integrated into device components with active properties. Specifically, we demonstrate the seamless interweaving of five different materials, including (1) emissive semiconducting inorganic nanoparticles, (2) an elastomeric matrix, (3) organic polymers as charge transport layers, (4) solid and liquid metal leads, and (5) a UV-adhesive transparent substrate layer. As a proof of concept for demonstrating the integrated functionality of these materials, we 3D printed quantum dot–based light-emitting diodes (QD-LEDs) that exhibit pure and tunable color emission properties. By further incorporating the 3D scanning of surface topologies, we demonstrate the ability to conformally print devices onto curvilinear surfaces, such as contact lenses."