Scalable Noninvasive Organic Fiber Lithography for Large-Area Optoelectronics

Abstract

The development of precise, chemical-free, and low-cost pixel patterning with high resolution and throughput instead of conventional photolithography is very important for large-area flexible organic light-emitting diode (OLED) displays or solid-state lightings with high aperture ratio. Here, a novel scalable and noninvasive lithography is reported as a pixel patterning method for OLEDs using highly aligned printed organic fiber arrays in large area. Use of electrohydrodynamic organic nanowire printing (ONP) enables highspeed large-area fabrication and precise positioning of poly(9-vinylcarbazole) (PVK) fiber pixel separator arrays without chemical damage. Due to circular cross-section of PVK fibers, clear and effective separation of organic and metal cathode layers by PVK fibers is achieved. Easy control of interfiber separation in ONP also enables the demonstration of green OLED subpixels with different pixel widths (400, 200, 100 mu m), which shows almost the same current efficiency and luminance as OLEDs without PVK fibers; i.e., PVK fiber pixel separators in OLEDs do not degrade OLED characteristics because the devices maintain almost the same electroluminescent area. Furthermore, it is demonstrated that individually well-aligned organic fibers are useful for pixel patterning of large-area, flexible OLEDs by fabricating a large-area (3 cm x 3 cm) white OLED and a flexible dot-matrix-display-type OLED.