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 high‐speed 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 μm), 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 × 3 cm) white OLED and a flexible dot–matrix‐display‐type OLED.

Recent progress on electrohydrodynamic nanowire printing

“…It is an improved method which avoids the use of H 2 gas in the reduction process. Al-NF electrodes can be produced by lithography around PVK NFs mask [13] (Fig. 6).…”

“…This review focuses on the evolution and application of the electrohydrodynamic nanowire printing (e-NWP) [1][2][3]. e-NWP can be used to precisely control the deposition of nanofibers (NFs) for use in printing of flexible electronics, micro-nanosize devices, and biological tissues [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Therefore, the deposition of NFs in orderly arrangements has achieved wide applicability in electrostatic spinning technology .…”

“…e-NWP was introduced in 2013 [1]; it overcame the demerits of traditional electrospun fibers such as disorder and poor control in position, and realized precise manipulation of single nanowires (NWs). e-NWP allows preparation of highly-ordered polymer NWs, metal doped organic NWs (ONWs) and metal-film NWs on flexible substrates with high efficiency on a large area [8][9][10]13,17,20]. By use of e-NWP, the diameter, number and position of NWs can be controlled according to the requirement of the NW array, thus avoiding the need for secondary operations to align the NWs [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

“…Electronic devices based on NWs show high integration, low energy consumption and flexibility [4][5][6][8][9][10][12][13][14][15][16][17][18]20]. e-NWP can be used to adjust the electrical properties of the device for applications in field effect transistors (FETs), sensors, memories, and bio-mimetic devices.…”

Tunable Two-Dimensional Patterning of a Semiconducting and Nanometer-Thin C60 Fullerene Film Using a Spatial Light Modulator

“…The field of organic electronics is in rapid development because of the easy tunability, soft and flexible nature, and facile processing of the constituent organic semiconductor (OSC). − However, the ability to pattern a nanometer-thin OSC layer with retained electronic properties is an additional critical requirement for the function, or improved operation, of a number of applications, including photodetectors, − sensors, , emissive devices, , and electronic circuits. , It is therefore not surprising that a plethora of different patterning methods, such as transfer stamping, , gravure printing, self-assembly, − cross-linking by electron and ion beams, , and photolithography using a sacrificial photoresist, , have been developed during recent years.…”