Highly oxidation-resistant silver nanowires by C_xF_y polymers using plasma treatment

We demonstrate plasma-treated Ag nanowires (NWs) as flexible transparent electrode materials with enhanced long-term stability against oxidation even in a high humidity environment (80% humidity, 20 °C). Through a simple fluorocarbon (C₄F₈ or C₄F₆) plasma treatment method, a C_xF_y protective polymer was sufficiently cross-linked and attached on the surface of the AgNWs strongly and uniformly. Even though C₄F₈ and C₄F₆ activate differently on the AgNW surface due to the different dissociated radicals formed in the plasma, it was found that the C_xF_y protective polymers obtained by both chemicals work similarly as a protective layer for transparent conductive electrodes; a nearly constant sheet resistance ratio (R _s/R _o) of 1.6 was found for AgNWs treated with C₄F₈ and C₄F₆ plasmas, while the AgNWs without the plasma treatment exhibited a ratio of 176.2 after 36 days in a harsh environment. It is believed that the fluorocarbon plasma treatment can be used as a key method for ensuring long-term oxidation stability in numerous electronic applications including flexible solar cells utilizing various types of metallic nanowires. (paper)