Silver Nanoparticles Inks for Use of Ink-Jet Printing

초록

Silver nanoparticles ink for ink-jet printing has been successfully used in the last decade for a number of applications, such as electrode or circuit pattern of Plasma display (PDP), Radio Frequency Identification (RFID) and Photovoltaic solar cell.1,2 Recently, the most common method for the preparation of silver nanoparticles in the ink is to use stabilizer, such as alkylamines, alkylthiols, ionic or non-ionic polymers and so on.3 However, these methods have a problem not to be applied on plastic substrate for electronics, which was decomposed below 200℃, because these stabilizers are difficult to be removed at low sintering temperature. Therefore, to lower sintering temperature, we prepared the silver complex ink by dispersing silver neodecanoate in organic solvent. Also, we found that the reduction of silver complex ink could be accelerated at low sintering temperature, if an appropriate reducing agent was added. So, metallic silver nanoparticles ink were prepared by reducing the silver complex ink with a weak reducing agent. TGA curves showed the thermal reduction of silver complex ink into pure metallic silver between 140℃ and 230℃ under air conditions. Spin-coated silver complex ink film had a resistivity of 4.5?10-5 Ω?cm after sintering above 160℃. But, as a result of using reduced silver nanoparticle ink instead of silver complex ink, the sintering temperature was significantly decreased from 160℃ to 130℃. And the resistivity of silver nanoparticle ink was 1.4?10-4 Ω?cm. The structure of reduced silver nanoparticles was determined by XRD. Also, size and morphology of reduced silver nanoparticles were observed by TEM. Surfaces and cross-sections of the spin-coated films and ink-jet patterns were investigated by SEM. Finally, silver complex ink was tested by using silver complex ink for production of pure metallic films on the polyimide. The results indicated that it could be suitable for a conductive ink.