Nozzle-printed and fabric-based organic light-emitting diodes

Abstract

The werable organic light emitting diodes (OLEDs) with fabric substrate can be most promising candidates for next generation display or lighting source because of their advantages of light weight, free-form design, flexible and werable applications. The sheet resistance of ITO films without PVA layer by roll-to-roll sputtering method were varied from 10k to 25 kΩ/sq, which are due to rough fabric surface morphology. The ITO films with PVA layer exhibits a low sheet resistance values from 60 to 80 Ω/sq, which is about 1000 times better than the ITO film without the PVA layer. The fabric surface without PVA layer was very rough, and it was not improved after ITO film coating on it. On the other hand, the fabric substrate with planarization layer showed a uniform and smooth surface with twisted patterns of polyester fabric, which can be confirmed that the PVA layer was uniformly coated on the cross-section of the fabric. These results are well agreed with the sheet resistance values of ITO films deposited on fabrics without and with the planarization layer. The current density and luminance values versus applied voltages of the printed OLEDs with planarization layer showed lower turn-on voltage and higher luminance values of about 1000 cd/m2 than the device without planarization layer. We firstly demonstrated the nozzle-printed OLEDs on the fabric subtrates for wearable display. The fabric substrate as well as ITO-coated fabric substrate with PVA layer showed a uniform and wavy surface with unique fabric patterns as a whole, which can be confirmed that the PVA layer was uniformly coated on the cross-section of the fabric.