Cycloaliphatic epoxy resin (3–4-epoxycyclohexane) methyl 3–4-epoxycyclohexyl-carboxylate (ECC) was formulated with flexible hydrogenated bisphenol A diglycidyl ether (HBADGE) to inspect the influence of chain flexibility on the performance and reliability of epoxy packaged Light-emitting Diode (LED). The properties of epoxy encapsulants were characterized by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), ultraviolet visible (UV–vis) spectrophotometer, thermomechanical analyzer (TMA), scanning acoustic microscopy (SAM), and scanning electron microscopy (SEM). With the incorporation of flexible HBADGE, favorable properties were obtained, such as decreased thermal expansion coefficient (CTE), lowered storage modulus at reflow temperature, and depressed equilibrium water uptake for the epoxy packaging materials. The light transmittance of encapsulants differed after thermal and UV aging. Compared with Neat ECC and Neat HBADGE, the HBADGE-modified encapsulants endowed LED devices with good performance and high reliability.
Dingyan Xu,Qun Wan,Siyao Wu,Yu Zhao,Xinglei Xu,Liang Li,Gufeng He
Lead halide perovskites have been considered promising materials for optoelectronic applications owing to their superior properties. CsPbBr3 nanocrystals (NCs) with a narrow particle size distribution and a narrow emission spectrum are synthesized by ligand-assisted re-precipitation (LARP), a low-cost and facile process. In inverted CsPbBr3 NC LEDs, a dual hole injection layer (HIL) of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN)/MoO3 is introduced to enhance hole injection and transport, because HAT-CN can extract electrons easily from the hole transport layer and leave a large number of holes there. The current and power efficiencies of the optimized device with a dual HIL are 1.5- and 1.8-fold higher than those of the single HIL device. It is believed that the dual HAT-CN/MoO3 HIL effectively promotes hole injection and has promise for application in many other devices.
Hua Wu,Yu Zhang,Min Lu,Xiaoyu Zhang,Chun Sun,Tieqiang Zhang,Vicki L. Colvin,William W. Yu
Cesium lead halide perovskite nanocrystals (NCs) possess excellent optical properties at visible wavelengths with great promise for applications in luminous display fields. We demonstrate a method to modify the surface ligand passivation of perovskite NCs for enhanced colloidal stability and emitting properties by incorporating didodecyl dimethyl ammonium bromide (DDAB). The photoluminescence quantum yield of the NC solution was improved to 96% from 70% and the perovskite film showed fewer trapped sites and enhanced carrier transport ability. The thus fabricated electroluminescent perovskite NC-LEDs exhibited a bright luminance of 11 990 cd m−2, corresponding to 4-times improved external quantum efficiency (EQE), compared to the control device using regular NCs without DDAB.
危险品化学品经营许可证（带存储）