Advances in color-converted micro-LED arrays

Abstract

The development of a full-color micro-display at the Industrial Technology Research Institute (ITRI) was reviewed in this study. The blue microdisplay with 960 × 540 pixel arrays and 1984 PPI resolution is demonstrated on a CMOS active matrix addressing circuit. Different methods of fabricating such a micro-panel are developed to overcome the limitation in mass transfer. For the device size ranging from 5-100 micrometers, lowcurrent external quantum efficiency of 10%-14% can be obtained. To achieve a full-color scheme, we adapt color-conversion layer design and use colloidal quantum dots as the illuminating material. A full-color array on a transparent substrate of 170 PPI resolution was demonstrated with a large-area blue LED backlight. The red and green pixels were fabricated by a photolithography process and had a size of 30 μm. The FWHM of 21 and 28 nm and the quantum yield of 28% and 41% for the green and red pixels, respectively, were measured by a 2D spectroradiometer. With superior color provided by quantum dots, it shows a wide color gamut that can fill 87% of Rec. 2020 color space.

Colloidal Quantum Dot Enhanced Color Conversion Layer for Micro LEDs

“…In the past, many groups demonstrated similar designs like Figs. 1 (b) and (c) [10,24], and a variety of designs can be found in [25]. Some adjustments could be necessary because of the differences in details of the devices.…”

“…No mass-transfer will be needed in this scheme. Several groups (including ITRI) have also demonstrated such technologies [9][10][11]. As for the material for color conversion, a strong illuminative capability is necessary.…”

Prospects and challenges of mini‐LED, OLED, and micro‐LED displays

“…display applications, two methods have been proposed to assemble the backplane driver circuitry and LED array: flip-chip bonding and wafer bonding. [55][56][57][58] For flip-chip bonding, the μLED is fabricated on the LED substrate, and the metal bonding ball is prepared on the complementary metal-oxidesemiconductor (CMOS) substrate. After that, two wafers are aligned and bonded by thermal-compression method.…”

Full-Color Realization of Micro-LED Displays

“…Micro-LED technology was first proposed by a research team at Texas Tech University in 2000 [ 3 ]. The pixel pitch limit to distinguish Mini-LEDs and micro-LEDs is 100 μm, and those smaller than 100 μm are defined as micro-LEDs [ 4 ]. With the advancement of the manufacturing process, the pixel size and pixel pitch of micro-LEDs have gradually decreased from 100 μm.…”