title: High-Power Genuine Ultraviolet Light-Emitting Diodes Based On Colloidal Nanocrystal Quantum Dots.
abstract: Thin-film ultraviolet (UV) light-emitting diodes (LEDs) with emission wavelengths below 400 nm are emerging as promising light sources for various purposes, from our daily lives to industrial applications. However, current thin-film UV-emitting devices radiate not only UV light but also visible light. Here, we introduce genuine UV-emitting colloidal nanocrystal quantum dot (NQD) LEDs (QLEDs) using precisely controlled NQDs consisting of a 2.5-nm-sized CdZnS ternary core and a ZnS shell. The effective core size is further reduced during the shell growth via the atomic diffusion of interior Cd atoms to the exterior ZnS shell, compensating for the photoluminescence red shift. This design enables us to develop CdZnS@ZnS UV QLEDs with pure UV emission and minimal parasitic peaks. The irradiance is as high as 2.0-13.9 mW cm(-2) at the peak wavelengths of 377-390 nm, several orders of magnitude higher than that of other thin-film UV LEDs.
authors.affiliation: †Department of Electronic Engineering, Dong-A University, Busan 604-714, Korea.
authors.forename: Jeonghun
authors.initials: J
authors.lastname: Kwak
authors.affiliation: §School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea.
authors.forename: Jaehoon
authors.initials: J
authors.lastname: Lim
authors.affiliation: ∥Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University, Seoul 151-744, Korea.
authors.forename: Myeongjin
authors.initials: M
authors.lastname: Park
authors.affiliation: ⊥Department of Chemistry, Seoul National University, Seoul 151-747, Korea.
authors.forename: Seonghoon
authors.initials: S
authors.lastname: Lee
authors.affiliation: §School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea.
authors.forename: Kookheon
authors.initials: K
authors.lastname: Char
authors.affiliation: ∥Department of Electrical and Computer Engineering, Inter-university Semiconductor Research Center (ISRC), Seoul National University, Seoul 151-744, Korea.
authors.forename: Changhee
authors.initials: C
authors.lastname: Lee
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D003102:Colloids; D053758:Nanoparticles / Q000737:chemistry*; D045663:Quantum Dots / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D014466:Ultraviolet Rays; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D003102:Colloids; D013440:Sulfides; D017967:Zinc Compounds; C034939:cadmium sulfide; C031238:zinc sulfide
keywords: quantum dot light-emitting diodes; quantum dots; ultraviolet; ultraviolet light-emitting diodes