Two models of the Eiffel Tower int he dark one is luminescent blue and the other is luminescent green

Source: © Zhu et al, Science 2024

Two 3D-printed light-emitting Eiffel Towers under 254nm UV excitation

By stabilising perovskites in a supramolecular assembly, US researchers have produced effective photoluminescent materials that can be formulated into thin films and 3D printer inks. The supramolecular approach simplifies the synthesis of the perovskites and could open the door to their wider use in light-emitting devices.

A research team led by Lawrence Berkeley National Laboratory and University of California, Berkeley materials scientist Peidong Yang has created supramolecular assemblies using crown ethers and hafnium and zirconium-containing perovskites. The perovskites feature octahedral metal centres of hafnium or zirconium bound to six halide anions. These materials would usually be highly air and moisture sensitive, but the use of crown ethers stabilises them, allowing for a much simpler synthesis protocol. Yang’s team developed a solution-based synthesis taking place at 200°C, in comparison to the solid-state reactions performed at 1000°C that have previously been required to produce these types of perovskites.

A diagram showing a 3d printed model being dunked into a resin vat of ink under a UV-LED lamp combined with a DMD chip

Source: © Zhu et al, Science 2024

The multimaterial 3D printing process

Depending on whether a hafnium or zirconium perovskite is used, the supramolecular assemblies emit either blue or green light. The solid powders show an impressive 96% photoluminescence efficiency with longer photoluminescence lifetimes than other halide perovskite systems. The team produced 3D printer inks using the materials by dispersing them in non-polar solvents. Dissolving polystyrene in the inks enhanced their processability. The team then used the inks to produce various structures, including miniature light-emitting Eiffel Towers.

Correction: This article was updated on 22 January 2024 to clarify Peidong Yang’s affiliation.