Browsing by Author "Melikov, R."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Placeholder
    ArticlePublicationMetadata only
    High quality quantum dots polymeric films as color converters for smart phone display technology
    (IOP Publishing, 2019-03) Sadeghi, S.; Mutcu, Süleyman Efdal; Srivastava, S. B.; Aydindogan, G.; Caynak, S.; Karsli, K.; Melikov, R.; Nizamoglu, S.; Mutcu, Süleyman Efdal
    Quantum dots (QDs) have high potential to fulfill the ever-increasing demands for high-quality displays due to their outstanding size-tunable optical properties, high quantum yield and reduced costs. The synthesis of efficient materials and their integration in uniform and thin polymeric films are necessary for displays. In this study, we synthesized red-and green-emitting Cd-based QDs with quantum yields of 52% and 74%, respectively. Weincorporated quantum dots into the polydimethylsiloxane (PDMS) polymer matrix by using doctor blade technique, which led to polymeric films with 123 mm x 68 mm dimensions for smart phone displays. We fabricated QD-polymeric films having thickness ranging from 100 to 500 mu m to investigate their color conversion and display application performances. By using the large-area QD-polymeric films on blue-emitting backlight unit, the NTSC and sRGB color gamut ratio was measured as 91% and 127%, respectively. Therefore, QD polymeric films show promise for smart phone applications.
  • Placeholder
    Conference paperPublicationMetadata only
    Thermal and optical performance of eco-friendly silk fibroin proteins as a cavity encapsulation over LED systems
    (ASME, 2015) Yuruker, Sevket Umut; Arık, Mehmet; Tamdoğan, Enes; Melikov, R.; Nizamoğlu, Sedat; Press, D. A.; Durak, Ilkem; Mechanical Engineering; ARIK, Mehmet; TAMDOĞAN, Enes; Yuruker, Sevket Umut; Durak, Ilkem; Tamdoğan, Enes
    The demand for high power LEDs for illumination applications is increasing. LED package encapsulation is one of most critical materials that affect the optical path of the generated light by LEDs, and may result in lumen degradation. A typical encapsulation material is a mixture of phosphor and a polymer based binder such as silicone. After LED chips are placed at the base of a cavity, phosphor particles are mixed with silicone and carefully placed into the cavity. One of the important technical challenges is to ensure a better thermal conductivity than 0.2 W/m-K of current materials for most of the traditional polymers in SSL applications. In this study, we investigated an unconventional material of the silk fibroin proteins for LED applications, and showed that this biomaterial provides thermal advantages leading to an order of magnitude higher thermal performance than conventional silicones. Silk fibroin is a natural protein and directly extracted from silk cocoons produced by Bombyx mori silkworm. Therefore, it presents a “green” material for photonic applications with its superior properties of biocompatibility and high optical transparency with a minimal absorption. Combining these properties with high thermal performance makes this biomaterial promising for future LED applications. An experimental and computational study to understand the optical and thermal performance is performed. A computational fluid dynamics study with a commercial CFD software was performed and an experimental set-up was developed to validate the computational findings to determine the thermal conductivity of the proposed material.