Realization of Excitation Wavelength Independent Blue Emission of ZnO Quantum Dots with Intrinsic Defects
- Realization of Excitation Wavelength Independent Blue Emission of ZnO Quantum Dots with Intrinsic Defects
- 최원국; 김홍희; 이연주; 이윤재; 정준경; 이연진; 박철민; 임상엽; Basavarj Angadi; 고금진; 강재욱
- ZnO; ZnO-GO; excitation wavelength; blue emission
- Issue Date
- ACS photonics
- VOL 7, NO 3-734
- Ecofriendly cation metal oxide quantum dots (QDs) are one of the promising candidates to replace for QDs containing expensive indium (In) or hazardous Cd- and Pb-elements. Super-Eg excitation wavelength (λex) dependent Zni-VO complex defects related characteristic emissions of green, yellow, and orange-red from ZnO QDs are completely inhibited by reducing oxygen vacancies through the hybridization of Zn interstitials in ZnO QDs with antibonding O-states of graphene oxide (GO) QDs. Thus, only λex independent violet-purple-blue (V-P-B) emission resulting from transitions among Frenkel pairs (Zni0-VZn) and the defects Zni0-Oi in ZnO-GO QDs with a high photoluminescence quantum yield (PLQY) of 92% is successfully achieved. White-light emission from PL QD-LEDs is achieved using a mixture of ZnO and ZnO-GO QDs with CIE (0.32, 0.34) excited by a UV LEDs chip (λ = 365 nm). Further, ZnO-GO QD-based deep-blue LEDs (λ = 438 nm) with luminance of 1980 cd/m2, a luminous efficacy (LE) of 2.53 cd/A, and external quantum efficiency (EQE) of 2.78% with CIE (0.16, 0.11) are also realized.
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