High‐resolution and high‐brightness full‐colour “Silicon Display” for augmented and mixed reality

Abstract

High‐brightness micro‐LED display bonded onto silicon backplane has been successfully demonstrated. The 0.38‐inch full‐colour active matrix LED microdisplay system consists of 352 × 198 pixels. Each pixel is 24 μm square composed of red, green, and blue (RGB) subpixels corresponding to a pixel resolution of 1053 ppi. Quantum‐dot materials are formed on III‐nitride blue micro‐LED array to convert blue light into red and green for full‐colour operation. We have confirmed that this microdisplay, which we call “Silicon Display” has wide colour gamut exceeding 120% of sRGB. We describe the advantage of this colour‐converting approach for the full‐colour micro‐LEDs. Progress toward higher resolution is also described. Brightness of more than 30 000 cd/m2 has been confirmed at a driving current density of 4 A/cm2 for 3000 ppi blue monochrome micro‐LED prepared for full‐colour Silicon Display. We believe our “Silicon Display” is ideally suited for near‐to‐eye displays for augmented and mixed reality.

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

“…In parallel, μLED microdisplays with PPI > 5000 have also been developed. 160,161 In comparison with OLED, μLED has advantages in high peak luminance 162 and long lifetime. Thus, it is more suitable for AR applications.…”

Luminescent Nanomaterials for Energy-Efficient Display and Healthcare

“…To achieve full-color, one can laminate a QDCC layer onto the blue micro-LED array, as Figure c (upper part) depicts . Compared to the mass transfer process that transfers RGB micro-LED chips from the fabrication wafers to a display substrate, which has a limited resolution density (normally <1500 pixels per inch, ppi), the color-converted micro-LED display can achieve a higher pixel density (∼3000 ppi) through the wafer bonding process . In addition, as shown in the lower part of Figure c, the color-converted micro-LED display exhibits a wider color gamut (∼97% Rec.2020) than that of a RGB micro-LED display (∼75–80% Rec.2020) because the green LED has a broader emission spectrum (∼40 nm).…”

“…In addition to quantum efficiency drop, the high-concentration QDCC films still suffer from two optical loss mechanisms: inadequate absorption of the excitation light and low light extraction efficiency of the converted photons. The trapped converted light in the color-conversion layer could be reabsorbed by the QD materials or absorbed by the sidewall bank, which is usually formed between each sub-pixel to prevent color crosstalk,, . The severe color crosstalk in the QDCC layer results from its large aspect ratio (the ratio of QDCC’s thickness to sub-pixel width).…”

19‐3: Crucial Effect of Aspect Ratio of Quantum‐Dot Color‐Conversion Pixels on the Performance of High‐Resolution Full‐Color MicroLED Microdisplays

“…This will lead to the sub-pixel size below 5 m. 2 Considering the thickness of QDCC with a satisfied optical density is generally above 5 m, the aspect ratio (the width to thickness ratio) of the sub-pixel is smaller than 1. Under this condition, the bank will remove most of the source light due to the high light absorption of black bank.…”