Fabrication of OLEDs without photolithography patterning

We report on a new cost-cutting fabrication process for organic light-emitting diodes (OLEDs), requiring no photolithography patterning for indium-tin-oxide (ITO). We formed the patterned ITO electrodes using a sputtering deposition system. However, sputter-patterned ITO-based OLEDs caused leakage current on the slope of the ITO edges due to spike-like surface. To suppress it, an organic molecule was thermally evaporated as an insulating layer that covers the sputter-patterned ITO edges. Such an insulating organic molecule demands low carrier mobility. We found that the reverse current density of OLEDs based on this scheme was comparable to that of photolithography-patterned ITO-based OLEDs.

Images of green light emission from sputter-patterned and insulator-coated ITO-based OLED (SP/IC-OLED), insulator-uncoated ITO-based OLED (SP/IU-OLED), and sputter-patterned ITO-based and insulator-evaporated OLWD (SP/IE-OLED), and measured reverse current density of those devices versus bias voltage.Figure optionsDownload as PowerPoint slideResearch highlights
► We report on a new cost-cutting fabrication process for OLEDs.
► We formed the patterned ITO electrodes using a sputtering deposition system.
► Sputter-patterned ITO-based OLEDs caused leakage current due to spike-like surface.
► An organic molecule was thermally evaporated as an insulating layer.
► The reverse current density of OLED based on this scheme was much reduced.