3200 ppi Matrix-Addressable Blue MicroLED Display

Abstract

In this article, an active matrix (AM) micro light-emitting diode (MicroLED) display with a resolution of 1920 × 1080 and a high pixel density of 3200 pixels per inch (ppi) is reported. The single pixel with a diameter of 5 μm on the MicroLED array exhibits excellent characteristics, including a forward voltage of 2.8 V at 4.4 μA, an ideality factor of 1.7 in the forward bias of 2–3 V, an extremely low leakage current of 131 fA at −10 V, an external quantum efficiency of 6.5%, and a wall-plug efficiency of 6.6% at 10.2 A/cm2, a light output power of 28.3 μW and brightness of 1.6 × 105 cd/m2 (nits) at 1 mA. The observed blue shift in the electroluminent peak wavelength is only 6.6 nm from 441.2 nm to 434.6 nm with increasing the current from 5 μA to 1 mA (from 10 to 5 × 103 A/cm2). Through flip-chip bonding technology, the 1920 × 1080 bottom-emitting MicroLED display through the backside of a sapphire substrate can demonstrate high-resolution graphic images.