Ultra-thick inkjet-printed quantum dots layer for full-color micro-LED displays.

Micro-LEDs have promising development potential in display applications because of their outstanding performance. Achieving a full-color display based on micro-LEDs is one of the most important issues in commercial applications. In this paper, an effective method based on quantum dots and blue micro-LEDs was developed. Using an etching method, a thick black matrix was fabricated to reduce crosstalk and form a thick bank for quantum dots. Quantum dots were deposited in a thick black matrix using inkjet printing technology. With blue micro-LEDs, inkjet-printed quantum dot films can realize effective color conversion. The integrated blue micro-LEDs and red/green quantum dot films can achieve full-color displays without color filters, because the blue light leakage in the color conversion film can be reduced by the quantum dots themselves. The results suggest that inkjet-printed quantum dots are a promising way to achieve full-color micro-LED displays.

Identifying the role of carrier overflow and injection current efficiency in a GaN-based micro-LED efficiency droop model.

In this paper, we investigate the efficiency droop phenomenon in green and blue GaN-based micro-LEDs of various sizes. We discuss the distinct carrier overflow performance in green and blue devices by examining the doping profile extracted from capacitance-voltage characterization. By combining the size-dependent external quantum efficiency with the ABC model, we demonstrate the injection current efficiency droop. Furthermore, we observe that the efficiency droop is induced by injection current efficiency droop, with green micro-LEDs exhibiting a more pronounced droop due to more severe carrier overflow compared to blue micro-LEDs.

Ultra-bright green InGaN micro-LEDs with brightness over 10M nits.

An investigation of electrical and optical properties of InGaN micro-scale light-emitting diodes (micro-LEDs) emitting at ∼530 nm is carried out, with sizes of 80, 150, and 200 µm. The ITO as a current spreading layer (CSL) provides excellent device performance. Over 10% external quantum efficiency (EQE) and wall-plug efficiency (WPE), and ultra-high brightness (> 10M nits) green micro-LEDs are realized. In addition, it is observed that better current spreading in smaller devices results in higher EQE and brightness. Superior green micro-LEDs can provide an essential guarantee for a variety of applications.

Monolithic integrated optoelectronic chip for vector force detection.

Sensors with a small footprint and real-time detection capabilities are crucial in robotic surgery and smart wearable equipment. Reducing device footprint while maintaining its high performance is a major challenge and a significant limitation to their development. Here, we proposed a monolithic integrated micro-scale sensor, which can be used for vector force detection. This sensor combines an optical source, four photodetectors, and a hemispherical silicone elastomer component on the same sapphire-based AlGaInP wafer. The chip-scale optical coupling is achieved by employing the laser lift-off techniques and the flip-chip bonding to a processed sapphire substrate. This hemispherical structure device can detect normal and shear forces as low as 1 mN within a measurement range of 0-220 mN for normal force and 0-15 mN for shear force. After packaging, the sensor is capable of detecting forces over a broader range, with measurement capabilities extending up to 10 N for normal forces and 0.2 N for shear forces. It has an accuracy of detecting a minimum normal force of 25 mN and a minimum shear force of 20 mN. Furthermore, this sensor has been validated to have a compact footprint of approximately 1.5 mm2, while maintaining high real-time response. We also demonstrate its promising potential by combining this sensor with fine surface texture perception in the fields of compact medical robot interaction and wearable devices.