Organic-soluble CQDs with long-wavelength fluorescent colors were produced, and have been investigated in nonpolar and polar solvents, films, and LED devices.

Graphene quantum dots (GQDs) and a metal–organic framework were assembled to form a nanocomposite for solving the GQDs’ fluorescence quenching problem in WLEDs.

With rapid developments in display technology and high-speed communication, augmented reality (AR) and virtual reality (VR) are emerging as next-generation display platforms for human–machine interactions. Recently, many significant strides have been made for the micro-light-emitting diodes (Micro-LEDs) display. However, to satisfy the requirements of AR/VR application, the size and resolution density of display have become extremely important. In this article, a 0.39-in 1024 $\times$ 768 blue and green active-matrix Micro-LED display with 3400 PPI featuring a pixel size of 5.5 $\mu$ m and a pixel pitch of 7.5 $\mu$ m was designed and fabricated. The blue and green Micro-LED displays exhibit excellent electrical and optical characteristics, including the low forward voltage of 3.3 and 3.2 V, and the brightness reach 7.2 $\times$ 105 and 1.7 $\times$ 106 cd/m $^{\text{2}}$ (nits) at 1 mA, respectively. These microdisplays demonstrated 8-bit grayscale images and videos vividly through the control of PWM frame generated by the FPGA board. We expect that the presented method could pave the way toward high-performance Micro-LED displays for AR and smart glasses.

Recently, many significant strides have been made for the integration of micro-light-emitting diodes (Micro-LEDs) in display. However, the reflow process is usually accomplished under formic acid or hydrogen ambient, which is irritating, flammable, explosive, and very expensive. For reliable micro bumps in the flip-chip package, it is essential that the correlations among mechanical properties, fracture mechanisms, and interfacial reactions of micro bumps formed on a silicon substrate be understood. In this article, a novel under bump metallurgy (UBM) structure based on SiO ₂ openings was described, as a result of which the indium micro bump arrays with a pitch of 40 $\mu \text{m}$ and a diameter of 15 $\mu \text{m}$ were successfully fabricated by the reflow process via glycerol. The effect of reflow time and reflow temperature on the reliability of indium micro bumps was also investigated. Experimental results showed that the average shear strength of indium micro bumps peaked at the reflow conditions of 200 °C for 180 s and decreased with further increasing reflow time and temperature. It was considered that the stable AuIn ₂ intermetallic compounds (IMCs) formed toward the solder joint improved the shear strength after reflowed at 200 °C for 180 s. As the reflow time and temperature increased, the grain size of IMCs increased, which weakened the interfacial connection. In addition, the transfer and bonding reliability of Micro-LED chips through the flip-chip bonding process have also been discussed.

In this article, a 0.39-in $512\times384$ monochrome micro-light-emitting diode (Micro-LED) array was demonstrated using GaN epi-wafers on sapphire. The array, with a pixel size of $13~\mu \text{m}$ and a pixel pitch of $15~\mu \text{m}$ , is connected to the sapphire substrate by Au–Sn flip-chip bonding. A single pixel of Micro-LED shows an extremely low leakage current of 0.2 pA at −5 V and a low threshold voltage of 2.5 V. In the optical aspect, it has a maximum brightness of 10591.8 cd/ $\text{m}^{{2}}$ (50.79%) at 700 mA, uniformity of 52.88% (4213.185 cd/ $\text{m}^{{2}}{)}$ at small current 180 mA and 54.43% (10225.35 cd/ $\text{m}^{{2}}{)}$ at high current 550 mA. The full width at half maxima (FWHM) of the array ranges from 14.5 to 18.4 nm and the peak wavelength variation is 2.1 nm. And it shows a deep-blue emission with CIE coordinates of (0.1506, 0.0289) at 100 mA. The use of high density Au–Sn flip-chip bonding in this work demonstrates a promising solution for the future bonding technology of Micro-LEDs with CMOS, as well as a new direction for the study of high resolution microdisplays.