Concurrent self-assembly of RGB microLEDs for next-generation displays.

MicroLED displays have been in the spotlight as the next-generation displays owing to their various advantages, including long lifetime and high brightness compared with organic light-emitting diode (OLED) displays. As a result, microLED technology1,2 is being commercialized for large-screen displays such as digital signage and active R&D programmes are being carried out for other applications, such as augmented reality3, flexible displays4 and biological imaging5. However, substantial obstacles in transfer technology, namely, high throughput, high yield and production scalability up to Generation 10+ (2,940 × 3,370 mm2) glass sizes, need to be overcome so that microLEDs can enter mainstream product markets and compete with liquid-crystal displays and OLED displays. Here we present a new transfer method based on fluidic self-assembly (FSA) technology, named magnetic-force-assisted dielectrophoretic self-assembly technology (MDSAT), which combines magnetic and dielectrophoresis (DEP) forces to achieve a simultaneous red, green and blue (RGB) LED transfer yield of 99.99% within 15 min. By embedding nickel, a ferromagnetic material, in the microLEDs, their movements were controlled by using magnets, and by applying localized DEP force centred around the receptor holes, these microLEDs were effectively captured and assembled in the receptor site. Furthermore, concurrent assembly of RGB LEDs were demonstrated through shape matching between microLEDs and receptors. Finally, a light-emitting panel was fabricated, showing damage-free transfer characteristics and uniform RGB electroluminescence emission, demonstrating our MDSAT method to be an excellent transfer technology candidate for high-volume production of mainstream commercial products.

Evaluation of LABType® SSO HLA Typing using the Luminex Platform: Cord Blood Registry Typing for the Korean Population.

BACKGROUND: The performance of a new intermediate-resolution method using a PCR-Luminex platform and LABType® SSO A, B DRB1 kits as an HLA typing method for the cord blood (CB) registry of the Korean population was investigated. METHODS: A total of 1,413 cord blood units (CBUs) were enrolled - 1,382 from Koreans and 31 from non-Koreans or mixed-ancestry individuals. HLA-A, -B, and -DRB1 typing was performed using the LABType® SSO typing kits. HLA typing with the DNA method and 2-digit results are mandatory for the public CB bank in Korea according to the "CB Act." RESULTS: The proportions of ambiguous results in the 2-digit assignment were 14.6% (206/1,413) and 14.8% (205/ 1,382) among the total subjects and the Korean donors, respectively. In the 2-digit resolution, 3 different HLA-A types (69 CBUs), 31 HLA-B types (124 CBUs), and 3 HLA-DRB1 types (13 CBUs) showed ambiguous results. The 'most probable type' to the ambiguous results based on the reported Korean HLA allele frequencies were able to be assigned. The most probable results were 100% consistent with the confirmed types as determined by the HD kits (DRB1) and additional PCR-SBT or PCR-SSP tests (A and B). Luminex technology is more automated and less labor intensive than the conventional SSO typing method, and the results are less affected by differences between inspectors. CONCLUSIONS: Although it is not satisfactory as a sole confirmation test and cannot be used as a replacement for the PCR-SBT test, the combination of Luminex technology with LABType® SSO kits and population frequency data provides a proper typing platform that can be used as a qualifying test for CB registries.

Synergistic effects of SPR and FRET on the photoluminescence of ZnO nanorod heterostructures.

Solution-grown ZnO nanorods (NRs) were successfully conjugated with CdSe/ZnS quantum dots (QDs) and Ag nanoparticles (NPs) to suppress intrinsic defect emission and to enhance band-edge emission at the same time. First, high-density and high-crystallinity ZnO NRs of diameter 80­90 nm and length 1.2­1.5 µm were grown on glass substrates using a low-temperature seed-assisted solution method. The as-synthesized ZnO NRs showed sharp photoluminescence (PL) band-edge emission centered at ∼377 nm together with broad defect emission in the range of ∼450­800 nm. The ZnO NRs were decorated with CdSe/ZnS QDs and Ag NPs, respectively, by sequential drop-coating. The PL of CdSe/ZnS QD||ZnO NR conjugates showed that ZnO band-edge emission decreased by 73.8% due to fluorescence resonance energy transfer (FRET) and charge separation between ZnO and CdSe/ZnS by type II energy band structure formation. On the other hand, Ag NP||CdSe/ZnS QD||ZnO NR conjugates showed increased band-edge emission (by 25.8%) and suppressed defect emission compared to bare ZnO NRs. A possible energy transfer mechanism to explain the improved PL properties of ZnO NRs was proposed based upon the combined effects of FRET and surface plasmon resonance (SPR).