Printed electronics; Conductive ink; Silver nanoparticles (AgNPs); Chemical reduction synthesis

Printed electronics are a new generation of electronic devices, which have characteristics, such as, low manufacturing cost, long-time endurance, environmentally sustainable production methods, recycling, lower energy consumption, and higher efficiency. The main component of printed electronics is conductive ink. Silver nanoparticles (AgNPs) are commonly used as the conductive material in conductive ink due to its low electrical resistivity (high conductivity) and resistance to oxidation. AgNPs can be obtained by various methods which have both advantages and disadvantages. Among different methods to synthesize AgNPs, the chemical reduction method is the most common method for preparing AgNPs due to its simple production method and the ability to control the shape and size of NPs by varying the reaction parameters. In this method, AgNPs are obtained by reduction of silver nitrate using a reducing agent. Stabilizers are used to prevent aggregation and agglomeration of AgNPs. During chemical reduction, the reducing agent donates electrons to the silver ions (Ag+), causing silver to revert to its metallic form (Ag0). Many parameters such as temperature, reaction time, type and content of reducing agent, and pH have affected the size and shape NPs. In this paper, at first, synthesis of AgNPs by chemical reduction method is investigated with a focus on the effective parameters in the process and in the final section, a review on the preparation of conductive ink containing AgNPs for printed electronics applications is done.