3D printing of inorganic materials with nanoscale resolution offers a different materials processing pathway to explore devices with emergent functionalities. However, existing technologies typically involve photocurable resins that reduce material purity and degrade properties. We develop a general strategy for laser direct printing of inorganic nanomaterials, as exemplified by more than 10 semiconductors, metal oxides, metals, and their mixtures. Colloidal nanocrystals are used as building blocks and photochemically bonded through their native ligands. Without resins, this bonding process produces arbitrary three-dimensional (3D) structures with a large inorganic mass fraction (~90%) and high mechanical strength. The printed materials preserve the intrinsic properties of constituent nanocrystals and create structure-dictated functionalities, such as the broadband chiroptical responses with an anisotropic factor of ~0.24 for semiconducting cadmium chalcogenide nanohelical arrays.

Among the leading energy materials, metal tri-halide perovskite quantum dots (PQDs) with outstanding optoelectronic properties are at the forefront of current research. However, enormous challenges remain to be addressed, including hazardous components and poor stability, before achieving practical applications of PQDs. Although there are diverse methods to improve the stability of PQDs, it is of central importance to avoid damage during operation. Herein, we develop a pre-protected strategy in which the coating combines the advantages of doping with sodium ions to jointly improve stability. Because the stable Na-rich surface acts as a defence, it protects the PQDs from damage during the coating process; therefore, they retain their initial fluorescence. When employing these Na-rich PQDs as core materials of a coating, the highly fluorescent Na: CsPb(Br,I)₃@Al₂O₃ nanocomposites can maintain good stability even when directly immersed in water or exposed to illumination. Clearly, the combination of these features sheds light on the stabilization and applications of PQDs.