Patterning Complex Line Motifs in Thin Films Using Immersion‐Controlled Reaction‐Diffusion

Abstract

The discovery of self‐organization principles that enable scalable routes toward complex functional materials has proven to be a persistent challenge. Here, reaction‐diffusion driven, immersion‐controlled patterning (R‐DIP) is introduced, a self‐organization strategy using immersion‐controlled reaction‐diffusion for targeted line patterning in thin films. By modulating immersion speeds, the movement of a reaction‐diffusion front over gel films is controlled, which induces precipitation of highly uniform lines at the reaction front. A balance between the immersion speed and diffusion provides both hands‐on tunability of the line spacing () as well as error‐correction against defects. This immersion‐driven patterning strategy is widely applicable, which is demonstrated by producing line patterns of silver/silver oxide nanoparticles, silver chromate, silver dichromate, and lead carbonate. Through combinatorial stacking of different line patterns, hybrid materials with multi‐dimensional patterns such as square‐, diamond‐, rectangle‐, and triangle‐shaped motifs are fabricated. The functionality potential and scalability is demonstrated by producing both wafer‐scale diffraction gratings with user‐defined features as well as an opto‐mechanical sensor based on Moiré patterning.

Designing Complex Tapestries with Photography‐Inspired Manipulation of Self‐Organized Thin‐Films

“…To produce uniform MPF's, we steadily immerse a gelatin thin film (0.3 mm) into a solution of silver nitrate (0.4 M), yielding silver chloride (AgCl) nanoparticles arranged in tunable uniform microscopic (d = 10 − 30 μm) stripe patterns (Figure 2A,B I). [26,35] To make these patterns compatible with subsequent photographic processes and to increase the contrast of the pattern, we immerse the MPF into a photographic developer solution that reduces and converts all (AgCl) particles to Ag/Ag 2 O. Analysis with optical microscopy reveals a stark increase in contrast, and, importantly, shows that the original stripe pattern and spacing are preserved (Figure 2A,B II).…”

“…Additionally, we foresee new functionalities that exploit the unique combination of tunable long-range ordering with local customization. For instance, already layer stacking allows the formation of Moiré patterns, [26] which combined with local customization could now be designed for information processing, sensing, and advanced optical devices. Furthermore, if self-organized patterns are scaled one order of magnitude, these structures could exhibit structural coloration.…”

“…[22][23][24][25] Recently, we have developed a self-organization strategy based on reaction-diffusion to structure silver nanoparticles into well-defined micropatterned thin films (MPF's, Figure 1A). [26] By steadily immersing a gel thin-film into a solution with silver ions, we induce precipitation of silver nanoparticles in the gel. These nanoparticles order in highly uniform stripes, regulated by a reaction-diffusion process.…”

Light-controlled morphological development of self-organizing bioinspired nanocomposites

“…We also project that other self-organization processes such as Liesegang-inspired patterning or chemical gardens can be controlled using light-driven reactions. [48][49][50] As next step, integration of these self-organization and conversion principles are currently being developed.…”