title: Fabrication of white light-emitting diodes based on UV light-emitting diodes with conjugated polymers-(CdSe/ZnS) quantum dots as hybrid phosphors.
abstract: White light-emitting diodes (LEDs) were fabricated using GaN-based 380-nm UV LEDs precoated with the composite of blue-emitting polymer (poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(2-methoxy-5-{2-ethylhexyloxy)-1 ,4-phenylene)]), yellow green-emitting polymer (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)]), and 605-nm red-emitting quantum dots (QDs). CdSe cores were obtained by solvothermal route using CdO, Se precursors and ZnS shells were synthesized by using diethylzinc, and hexamethyldisilathiane precursors. The optical properties of CdSe/ZnS QDs were characterized by UV-visible and photoluminescence (PL) spectra. The structural data and composition of the QDs were transmission electron microscopy (TEM), and EDX technique. The quantum yield and size of the QDs were 58.7% and about 6.7 nm, respectively. Three-band white light was generated by hybridizing blue (430 nm), green (535 nm), and red (605 nm) emission. The color-rendering index (CRI) of the device was extremely improved by introducing the QDs. The CIE-1931 chromaticity coordinate, color temperature, and CRI of a white LED at 20 mA were (0.379, 0.368), 3969 K, and 90, respectively.
authors.affiliation: Department of Chemical and Biological Engineering, Korea University, 1 Anam-Dong, Sungbuk-Gu, Seoul 136-701, South Korea.
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Jung
authors.forename: Wonkeun
authors.initials: W
authors.lastname: Chung
authors.forename: Chang Hun
authors.initials: CH
authors.lastname: Lee
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Kim
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D003116:Color; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D012666:Semiconductors; D014466:Ultraviolet Rays; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D011108:Polymers; D018036:Selenium Compounds; D017967:Zinc Compounds; C058667:cadmium selenide; C044696:zinc selenide