Low-cost RFID tags would enable automated inventory and checkout in retail stores by replacing the ubiquitous UPC barcode. In this work the fabrication of the passive components for RFID tags is achieved primarily by inkjet printing, using a gold nanoparticle ink to generate conductive lines on plastic substrates. After considering the performance requirements of 13.56 MHz RFID passive devices, the all-printed devices are improved by using a combination of inkjet patterning with an electroless copper deposition. The results of this hybrid approach are shown to be far superior to printing alone, generating inductors with quality factors above 20.
The concept of solution-processing is then expanded to cover semiconductor and insulator materials, with a focus on transparent TFTs for active-matrix OLED displays. Zinc oxide TFTs are fabricated using chemical bath deposition followed by an anneal in oxygen ambient. Electron mobility as high as 3.5 cm^2/Vs is achieved, and mobility of 1.5 cm^2/Vs is achieved at low anneal temperatures (450 C), enabling the use of cheap glass substrates. These results present a significant improvement over amorphous silicon, and will allow the development of low-power high-resolution OLED displays.