Flexible and ultra-thin silver films with superior electromagnetic interference shielding performance via spin-coating silver metal–organic decomposition inks

Abstract

Herein, we present a clean, green and economical method to prepare flexible and ultrathin silver films for electromagnetic interference (EMI) shielding by thermal decomposition of metal–organic decomposition (MOD) inks. The non-particulate ink synthesized by complexing silver oxalate with 1,2-diaminopropane in ethanol solvent can be easily decomposed to pure silver at a quite low temperature in air. The efficient electrical transport network constructed by the interconnected nanoparticles of the silver film results in outstanding electrical properties and shielding performance, with an absorption-dominated mechanism. By curing the ink at 130 °C for 30 min, a more effective network structure for electron transport can be obtained. By the spin coating deposition method, the silver film with only a 200 nm thickness has an ultrahigh conductivity of 8.46 × 10⁶ S m⁻¹ and excellent shielding effectiveness of 51.1 dB at 10.3 GHz in the X band, which is the highest shielding effectiveness of the film with such thin thickness so far. The factors affecting the EMI shielding performance of silver films were elucidated, including the heat treatment process, ink concentration and spin coating times, and the relationship between the microstructure and the properties of the film was established. This work indicates that silver metal–organic decomposition inks will be a favorable choice for the industrial production of EMI shielding applications.