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Efficient methods for the controlled syntheses of metal nanocrystals are important for emerging electronics and catalysis applications. In this report, we present a solution-based method for the fabrication of Pt-coated Ag nanocrystal (NC) thin films through the use of ligand-exchange and electroless deposition. We successfully prepared uniform or bumpy Ag@Pt core/shell structures, as well as Ag–Pt alloy structures, through control of the reducing agents. We first report the Ag–Pt alloy structures can be synthesized by low-temperature and solution-based process of post treatment that exhibited high catalytic activity toward the hydrogen evolution reaction.

In this study, we introduce a strategy to introduce solution-processed interfacial layers in nanocrystal (NC) thin films to fabricate high-performance strain sensors. SiO2 interfacial layers are chemically introduced in ligand-exchanged Ag NC thin films to increase the tunneling gap or inter-particle distance between each Ag NC. In this way, the charge-transport mechanism is manipulated, leading to unique electromechanical properties with a high gauge factor. All solution-processed strain gauge sensors with high stability, durability, and sensitivity are fabricated. The sensor successfully measured delicate movements such as finger motions, demonstrating its possible application in electronic skin.

In this study, a highly stretchable white-light electroluminescent device is fabricated using chemically designed perovskite nanocrystals (NCs). To incorporate perovskite into a stretchable polymer matrix without any degradation, gel-type silica-coated CsPbBr3 and CsPbBrxI3-x NC inks are prepared using (3-aminopropyl) triethoxysilane (APTES) with a sacrificial solvent of hexane. The chemical, optical, and structural properties of powdered and gel-type perovskite NCs with and without APTES are investigated. Silica shell with APTES treatment improves the stability of perovskite NCs, and gel-type inks improve the dispersivity in the polymer matrix. These enable the fabrication of stretchable and luminescent NC/polymer matrices with enhanced and uniform luminescence properties. By utilizing these materials, we propose a stretchable electroluminescent device emitting strong white light that is close to the ideal white position in Commission Internationale de l'eclairage (CIE) with optical simulation. Herein, we fabricate a multi-color filter with high color reproducibility on stretchable blue electroluminescent devices for white-light generation. Furthermore, all-solution-processed, color-filterless, stretchable, white-light electroluminescence devices with excellent optical and mechanical properties are fabricated.

Herein, we introduce a unique nanomaterial chemical transformation (NCT) process whereby selenium (Se) anion is introduced to colloidal silver (Ag) nanocrystals (NCs) to create nanostructured silver selenide (Ag2Se). We present a complete suite of material characterizations, including chemical, structural, optical, and electrical characterizations to understand the details of the transformation process. The Ag2Se thin-films obtained through the NCT process exhibit degenerately-doped n-type semiconductor characteristics with high carrier mobility. We discuss the chemical mechanism that drives the material transformation and elucidates the origin of doping in these semiconducting thin-films. We also demonstrate the robustness of Ag2Se thin-films toward mechanical strain and temperature cycling stress for flexible device applications. We believed that the NCT process demonstrated here is of wide applicability to other material systems which can open up new avenues for solid-state chemistry and device engineering research.