Single‐Step Assembly of Large‐Area, Transparent Conductive Patterns Induced Through Edge Adsorption of Template‐Confined Au‐Thiocyanate

Abstract

been applied for creating microscale surface organization.[ 8 ] Related metal patterning technologies based upon evaporationinduced self-alignment, [9][10][11] direct laser sintering, [12][13][14] and micro-(or nano-) transfer molding have been also reported. [15][16][17][18][19][20][21] However, these techniques also generally require that metallic nanostructures (i.e., nanorods, nanowires, etc.) are prepared prior to surface deposition and patterning. Methodologies combining top-down and bottom-up approaches have been also introduced. [ 22 ] We present a novel, versatile "chemical lithography" strategy for fabricating largearea, organized conductive gold micropatterns. The technology employs a simple single-step process in which a gold complex undergoes slow crystallization/reduction in a confi ned environment. Specifi cally, we demonstrate that diverse patterns of well-defi ned, uniform Au microwires are spontaneously formed through incubation of gold thiocyanate [Au(SCN) 4 − ] dissolved in an organic-solvent/water mixture within confi ned spaces at the interface between polymer molds and surfaces underneath them. The patterning technology is generic in nature as Au organization is only determined by the mold employed. Importantly, the entire patterning process-Au reduction and crystallization, control of microwire size, shape, and organization-occurs spontaneously without any nanostructure pre-synthesis steps. Furthermore, neither stabilizing or shape-directing ligands, nor reducing agents are required for assembly of the Au patterns, as the reducing electrons originate from the thiocyanate ligands. The Au microwires are electrically conductive and produce optically transparent surfaces, pointing for practical uses of the technology as a platform for creation of diverse optoelectronic assemblies and devices. Results and DiscussionThe experimental scheme is illustrated in Figure 1 . An organicsolvent/water solution containing KAu(SCN) 4 is spread upon a solid substrate (Figure 1 A). A polydimethylsiloxane (PDMS) mold having pre-designed pattern is then placed upon the fi lm, effectively confi ning the Au(SCN) 4 − solution into the spaces determined by the stamp (Figure 1 B). Incubation of the gold complex solution within the confi ned areas prevents rapid evaporation of the solvent mixture, instead resulting in slow deposition of Au microwires following crystallization and reduction of the Au 3+ ions by the thiocyanate residues. Recent studies have shown that

Recent progress of patterned electrodes in wearable electronics: fabrication and application

“…Efficient fabrication methods which are not only simple and economical but also not limited to the kinds of substrates have gotten a lot of attention. In this review, the patterning methods contain traditional micromachining methods such as lithography or etching [10][11][12][13][14][15][16][17][18][19][20][21], soft lithography [22][23][24][25][26][27][28][29][30][31][32][33][34][35], printing process [36][37][38][39][40][41][42][43][44][45][46], laser direct writing (LDW) [47][48][49][50][51], and self-assembly [52][53][54][55][56][57]…”

Porous Gold Nanotubes for Enhanced Methanol Oxidation Catalysis

“…We have recently introduced a new strategy for fabrication of complex Au nanostructures using spontaneous crystallization and reduction of gold thiocyanate [Au(SCN) 4 − ] . Specifically, it has been shown that KAu(SCN) 4 forms diverse Au nanoparticle morphologies in aqueous and organic solutions, including nanoribbons, nanowires, and patterned NPs, which have been employed as platforms for transparent electrodes,, nanowires, piezoresistive sensors, catalysts, and surface‐enhanced Raman scattering (SERS)‐active substances . Importantly, in all these systems, the Au(SCN) 4 − gold precursor undergo distinctive self‐assembly via spontaneous crystallization and reduction processes, without co‐addition of reducing agents nor templates.…”

Microstructured Hydrogel Templates for the Formation of Conductive Gold Nanowire Arrays

“…They are of high interest, e.g., in the fields of optoelectronics or sensors . To meet the need in surface functionalization, many approaches have been developed to produce 1D structures on the micro‐ and nanoscale, utilizing techniques which can be classified into lithography techniques (top‐down) and self‐assembly processes (bottom‐up), respectively. In case of top‐down processes, electron beam lithography (EBL) techniques are capable of generating defined nanostructures.…”