Research on Simulation Design of MOS Driver for Micro-LED

Micro-LED is a new technology applied in the display field, which has the advantages of self-illumination, low power consumption, high brightness, long life and ultra-high resolution, and has broad application prospects. Using MOS devices to drive micro-LED can enable each unit to have its own drive, thus improving the yield and reducing the subsequent repair processes. In this paper, Sentaurus TCAD simulation software is used to design and simulate NMOS/PMOS devices and their driving circuits. For the first time, CMOS inverters are used to directly drive Micro-LED. Three kinds of driving circuits are compared and analyzed according to their simulation results in output characteristics and transient characteristics. In terms of switching characteristics caused by output characteristics, a CMOS inverter driving a micro-LED circuit has no problems of incomplete turn-off and has greater advantages. In the switching characteristics aspect caused by transient characteristics, PMOS driving a micro-LED circuit has the shortest turn-on time and greater advantages. When compared with a micro-LED driven by an access current-limiting resistor, a micro-LED driven by a direct drive has a smaller on-time value and greater advantages

Effects of Die-Attach Quality on the Mechanical and Thermal Properties of High-Power Light-Emitting Diodes Packaging

The reliability of high-power light-emitting-diode (LED) devices strongly depends on the die-attach quality because voids may increase junction temperature and total thermal resistance of LED devices. Die-attach material has a key role in the thermal management of high-power LED package by providing low-contact thermal resistance. Thermal and mechanical analyses were carried out by experiments and thermal simulation. The quantitative analysis results show that thermal resistance of die-attach layer (thermal resistance caused by die-attach material and voids in die-attach layer) plays an important role in total thermal resistance of high-power LED packaging according to the differential structure function of thermal transient characteristics. The increase of void fraction in die-attach layer causes the increases of thermal resistance of die-attach layer; the thermal resistance increased by 1.95 K/W when the void fraction increased to 62.45%. The voids also make an obvious influence on thermal stress and thermal strain of chip; the biggest thermal stress of chip was as high as 847.1 MPa compared to the 565.2 MPa when the void fraction increases from being void-free to 30% in the die-attach layer

Design and Implementation of Multi-Channel Readout Circuits for Low-Temperature Environments

Infrared sensors and focal plane imaging arrays are among the most important types of devices in the field of aerospace applications. To effectively amplify the small signals collected by infrared sensors and focal plane imaging arrays for subsequent processing, a new multi-channel preamplifier circuit based on ultra-low temperatures was designed in this study to read the acquisition signals of such devices. The technology of an SMIC 180 nm CMOS with 1.8 V power was adopted to realize the circuit. Meanwhile, an eight-level adjustable gain switch was used to increase the selectivity of signal processing. According to the simulation’s results, the single-channel power consumption of the circuit in the 77 K ultra-low temperature environment was only 5.17 mW. The circuit could drive a large load of 200–400 pF with an open-loop gain of 131.4 dB, which showed excellent performance in driving large loads, providing high gain and consuming less power. Additionally, the circuit exhibited good aspects for front-end signal reading and processing of infrared sensors and focal plane arrays in extreme environments

Monoclinic Lu_2–<i>x</i>Sm_<i>x</i>WO₆‑Based White Light-Emitting Phosphors: From Ground–Excited-States Calculation Prediction to Experiment Realization

Through ground state and constrained density function calculations, Sm³⁺ ions luminescence in self-activated monoclinic Lu₂WO₆ was originated from intra 4f → 4f transitions, not inter 5d → 4f transitions. Theoretically the white luminescence was obtained by combining red and blue-green emissions of 4f energy levels and W–O charge transfer transitions. Experimentally, pure and Sm³⁺ doping Lu₂WO₆ powders were synthesized using solid phase reaction calcined in air atmosphere. By the analysis of X-ray photoelectron spectroscopy and Rietveld refinement, element Sm charge state was trivalent, and Sm³⁺ doping was concentration-dependent selectively doping in three Lu sites. With the increase of Sm³⁺ concentrations, the color coordinates changed gradually from blue (0.17, 0.17) through white light (0.33, 0.25) toward orange (0.44, 0.32) in the visible spectral under 325 nm excitation. On the basis of the theoretical prediction and experimental preparation, a white emission LED lamp was produced using a 365 nm ultraviolet chip and Lu_1.99Sm_0.01WO₆ phosphor. The present design method can be applied to select excellent activators from a large number of rare-earth (Re) ions like Sm³⁺ and Eu^3+/2+ or non-Re ions like Bi³⁺ and Mn⁴⁺ in various matrixes

Multifunctional semitransparent organic photovoltaics with high-throughput screened infrared reflector

Multifunctional semitransparent organic photovoltaics (ST-OPVs) combining power generation, light transparency, and heat rejection have emerged as a promising technology for application in building-integrated photovoltaic systems, but maximizing all of these features simultaneously is challenging. Herein, we show that high-throughput optical screening is essential to guide the design of infrared reflectors and enhance their synergy with organic absorbers. Taking advantage of a volatile additive, 1,3,5-trichlorobenzene, to improve the crystallinity of the binary PM6:L8-BO active layer, we developed an optimized infrared reflector, consisting of a Na3AlF6 (160 nm)/ZnSe (190 nm) bilayer, which concomitantly increases all of the key parameters of the reflector-free device. High-performance multifunctional ST-OPVs with a power conversion efficiency of 15.19%, an average photopic transmittance of 30.57%, a color rendering index of 81.86, and an infrared rejecting rate over 90% are demonstrated, providing practical prospects for future sustainable building-integrated photovoltaic systems