19‐4: Invited Paper: Emissive Displays with Transfer‐Printed Microscale Inorganic LEDs

Abstract

Major advances in flat panel displays can come from the pixel‐level integration of high performance microscale components fabricated on semiconductor wafers and transferred by advanced assembly methods onto large‐area substrates. Displays that use direct light emission from tiny inorganic light emitting diodes (µILEDs) have the potential to be very bright and power efficient. Transfer‐printing with elastomer stamps is a candidate assembly technology for making µILED displays, serving as the metaphorical bridge between the LED wafer and the display panel. This paper presents simple demonstrations of displays made from red, green, and blue µILEDs fabricated on gallium arsenide, silicon, and sapphire wafers, transferred to glass and plastic display substrates by transfer‐printing. The demonstrator displays exhibit interesting characteristics, including transparency, flexibility, repair‐ability, wide color gamut, and pulse‐width modulated active matrix driving schemes facilitated by transfer‐printed micro‐scale driver circuits.

44‐2: Invited Paper: More than microLEDs: Mass Transfer of Pixel Engines for Emissive Displays

“…In this process, the micro-components are first transferred to the non-native substrate, followed by metal redistribution layer deposition. In another embodiment involving flip-chip LEDs (as shown in Figure 2(b)), the target display substrate is pre-patterned with metal traces and during the transferprinting process, the electrodes of the microLEDs make electrical interconnection with the display substrate using a pressure activated interconnection process [11,14,15]. The pixel engines, shown in Figure 1, include conductive structures that allow formation of electrical interconnections using the pressureactivated interconnection process [13].…”

Micro Light‐Emitting Diodes for Display and Flexible Biomedical Applications

“…µLED technology will serve as a platform for large area and high performance display application due to its high contrast ratio, fast response time, and low power consumption . Researchers have suggested two strong candidates for realizing full‐color red‐green‐blue (RGB) thin‐film µLED displays: (i) color conversion from blue/UV µLEDs using quantum dots (QDs) and (ii) transfer of red, green, and blue µLEDs in three separate processes . Figure exhibits various demonstrations of µLED displays.…”

“…QD‐based color filters successfully converted the UV light of µLEDs to red, green, and blue light without color mixing. Figure b shows a process schematic of a passive‐matrix inorganic full‐color µLED (PMILED) display using stamping transfer of true RGB µLEDs . Self‐emissive full‐color µLEDs were separately transferred from the mother RGB III–V wafers to a display substrate using a patterned PDMS stamp, and interconnected by metal electrode lines.…”

“…b) Schematic illustration of passive‐matrix µLED (PMILED) full‐color display using stamping transfer method. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

32‐3: Invited Paper: 12.1‐inch 169‐ppi Full‐Color Micro‐LED Display Using LTPS‐TFT Backplane

“…However, high current driving by TFT circuits must be solved [3]. Therefore, most of the AM driving micro-LED displays adopt complementary metal-oxide semiconductor (CMOS) backplane [4][5][6][7] or a plurality of micro-CMOS ICs transferred onto the displays [8,9].…”