Versatile van der Waals Integration through Hydrogel-Assisted Laser Printing

Van der Waals integration for two-dimensional (2D) heterostructures offers a flexible method to assemble diverse materials into customized structures without requiring lattice matching or complex processing. Successful integration hinges on utilizing an effective and consistent transfer medium and technique. Liquid media have been used in wet-transfer processes due to their simplicity and cleanliness; however, they often yield subpar transfer quality and stability. In this study, we propose the use of structured liquids, such as hydrogels, as efficient transfer media for the reliable transfer of 2D materials and beyond. The hydrogel-assisted transfer approach enables cleaner transfers, achieving uniform internal strain distribution and enhanced transfer stability. Moreover, hydrogels are well-suited for layer-by-layer laser printing, as the transparency of hydrogel allows the laser beam to pass through for precise patterning and also it offers a clean interface between layers. We demonstrate that hydrogel-based laser printing supports the stacking of a wide range of materials, extending beyond 2D structures, which opens new possibilities for hybrid van der Waals integration in device fabrication.