MoS₂ has attracted significant attention as a next-generation semiconductor material to overcome the physical scaling limits of silicon-based devices due to its atomic thinness and excellent electrical properties. However, high contact resistance and the formation of Schottky barriers resulting from interface defects during the metal deposition process remain major bottlenecks that degrade overall device performance and reliability. In this study, we fabricated MoS₂ FETs by employing Sb₂Te₃, van der Waals (vdW) contacts. Minimized interface inhomogeneity was achieved through a hemispherical stamp-based dry transfer of h-BN for device encapsulation. h-BN encapsulation decreased the hysteresis window in the ±25 V gate voltage range from 17 V to 11.5 V compared to un-capped devices, confirming that charge trapping phenomena induced by external environmental factors were suppressed. Consequently, the dry transfer technique of h-BN using a hemispherical stamp demonstrated in this study provides a potential solution for securing the long-term reliability of MoS₂ devices with vdW contact by minimizing interface contamination.

Metal halide perovskite materials have emerged as promising candidates for next-generation optoelectronic applications owing to their outstanding optical properties and tunable emission characteristics. However, their practical application is hindered by poor environmental stability, especially under conditions of heat, moisture, and UV exposure, necessitating effective encapsulation strategies. This review summarizes recent progress in enhancing the environmental stability of perovskite nanocrystals through polymer matrix embedding, inorganic oxide encapsulation, and compositionally matched core-shell structures using homogenous perovskite derivatives. We discuss how polymers enhance the environmental and moisture stability of perovskite nanocrystals, how oxide-based shells (e.g., SiO₂, TiO₂) contribute to thermal robustness and barrier protection, and how homostructural core-shells provide lattice-matched defect passivation with improved long-term durability. A comprehensive understanding of the advantages and limitations of each encapsulation strategy, along with their rational integration, can accelerate the commercialization of perovskite-based technologies in various applications such as highcolor- purity displays, color conversion filters, and flexible optoelectronic devices.

Abstract: To study the encapsulation method for heat dissipation of high brightness organic light emitting diode (OLEI)), red emitting OLED of ITO (150 nm) / 2 TNATA (50 rim) / NPB (30 rim) / A1q3 1 vol.% Rubrene (30 nm) / Alq3 (30 nm) / LiF (0.7 nm) / Al (200 nm) structure was fabricated, which on Alq3 (150 nm) / LiF (ISo nm) as buffer layer and Al as protective layer was deposited to protect the damage of OLED, and subsequently it was encapsulated using attaching film and metal sheet. The current density, luminance and power efficiency was improved according to thickness of Al protective layer. The emission spectrum and the Commission International de L`Eclairage (CIE) coordinate did not have any effects on encapsulation process using attaching film and metal sheet The lifetime of encapsulated OLED using attaching film and metal sheet was 307 hours in 1,200 nm Al thickness, which was increased according to thickness of Al protective layer, and was improved 7% compared with 287 hours, lifetime of encapsulated OLEI) using attaching film and flat glass. As a result, it showed the improved current density, luminance, power efficiency and the long lifetime, because the encapsulation method using attaching film and metal sheet could radiate the heat on OLED effectively.

Encapsulant curing in terms of convection oven leads to thermal induced stress due to nonuniform thermal conductivity in LED package. We have adopted infrared (IR) light for silicone curing in order to release the stress. The light uniformity irradiated on an encapsulant surface is confirmed to be uniform by optical simulation. Shear strength of die paste using IR compared to convection oven is increased 19.2% at the same curing time, which indicates curing time can be shortened. The indentation depth difference between center and edge of silicone encapsulant in terms of convection oven and IR are 14.8% and 3.4%, respectively. Curing by IR also shows 2.3% better radiant flux persistency rate of LED at 85℃ after 1,000 h reliability test compared to convection curing.

Chip on board type white light emitting diode on metal core printed circuit board with high thixotropy silicone is fabricated by vacuum printing encapsulation system. Encapsulant is chosen by taking into account experimental results from differential scanning calorimeter, shearing strength, and optical transmittance. We have observed that radiant flux and package efficacy are increased from 336mW to 450mW and from 11.9 lm/W to 36.2 lm/W as single dome diameter is varied from 2.2 mm to 2.8 mm, respectively, Double encapsulation structure with 2.8 mm of dome diameter shows further significant enhancement of radiant flux and package efficacy to 667mW and 52.4 lm/W, which are 417mW and 34.8 lm/W at single encapsulation structure, respectively.

To study encapsulation method for large-area organic light emitting diodes (OLEDs), red emitting OLEDs were fabricated, on which Alq3 as organic buffer layer and LiF and Al as inorganic protective layers were deposited to protect the damage of OLED by epoxy. And then the OLEDs were attached to flat glass by printing method using epoxy. The basic structure of OLED doped with rubrene of 1 vol.% as emitting layer is ITO(150 ㎚)/2-TNATA(50 ㎚)/α-NPD(30 ㎚)/Alq3:Rubrene(30 ㎚)/Alq3(30 ㎚)/LiF(0.7 ㎚)/Al(100 ㎚). In case of depositing Alq3, LiF and Al and then attaching of flat glass onto OLED, current density, luminance, efficiency and driving voltage were not changed and lifetime was increased according to thickness of Al as inorganic protective layers. The lifetime of OLED/Alq3/LiF/Al_4/glass structure was 139 hours increased by 15.8 times more than bare OLED of 8.8 hours and 1.6 times more than edge sealed OLED of 54.5 hours.

To study encapsulation method for large-area organic light emitting diodes (OLEDs), red emitting OLEDs were fabricated, on which LiF and Al were deposited as inorganic protective films. And then the OLED was attached to flat glass by printing method using epoxy. In case of direct coating of epoxy onto OLED by printing method, luminance and current efficiency were remarkably decreased because of the damage to the OLED by epoxy. In case of depositing LiF and Al as inorganic protective films and then coating of epoxy onto OLED, luminance and current efficiency were not changed. OLED lifetime was more increased through inorganic protective films between OLED and flat glass than that without any encapsulation (8.8 h), i.e., 47 (LiF/Al/epoxy/glass), 62 (LiF/Al/LiF/epoxy/glass), and 84 h (LiF/Al/Al/epoxy/glass). The characteristics of OLED encapsulated with inorganic protective films (attached to flat glass) showed the possibility of application of protective films.