Designing highly conductive and stable silver nanocrystal thin films with tunable work functions through solution-based surface engineering with gold coating process

We fabricated highly conductive and stable silver nanocrystal (Ag NC) thin film electrodes with tunable work functions using an all-solution-based method involving sequential ligand exchange and gold (Au) coating processes. We studied the effect of the Au coating process on the ligand-exchanged Ag NC thin films and successfully demonstrated the formation of a thin Au layer on the surface of the Ag NCs. We investigated the morphological, structural, optical, chemical, and electrical properties of the Ag NC thin films before and after Au coating. The work function of the electrodes was precisely controlled by varying the treatment time and concentration of gold chloride trihydrate (HAuCl₄·3H₂O) solutions. The thermal stability of the Au coated Ag NC thin films in air was greatly enhanced, and an extremely low resistivity of 3.4 μΩcm was achieved. Taking advantage of this solution-based low-temperature process and using a minimal amount of Au for cost reduction, we fabricated all-NC-based high-performance flexible photodetectors.