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High‐Efficient Deep‐Blue Light‐Emitting Diodes by Using High Quality Zn x Cd 1‐ x S/ZnS Core/Shell Quantum Dots
Author(s) -
Shen Huaibin,
Bai Xianwei,
Wang Aqiang,
Wang Hongzhe,
Qian Lei,
Yang Yixing,
Titov Alexandre,
Hyvonen Jake,
Zheng Ying,
Li Lin Song
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201302964
Subject(s) - materials science , quantum dot , light emitting diode , quantum yield , optoelectronics , full width at half maximum , quantum efficiency , diode , luminous efficacy , core (optical fiber) , nanotechnology , optics , fluorescence , physics , layer (electronics) , composite material
High‐quality violet‐blue emitting Zn x Cd 1‐ x S/ZnS core/shell quantum dots (QDs) are synthesized by a new method, called “nucleation at low temperature/shell growth at high temperature”. The resulting nearly monodisperse Zn x Cd 1‐ x S/ZnS core/shell QDs have high PL quantum yield (near to 100%), high color purity (FWHM) <25 nm), good color tunability in the violet‐blue optical window from 400 to 470 nm, and good chemical/photochemical stability. More importantly, the new well‐established protocols are easy to apply to large‐scale synthesis; around 37 g Zn x Cd 1‐ x S/ZnS core/shell QDs can be easily synthesized in one batch reaction. Highly efficient deep‐blue quantum dot‐based light‐emitting diodes (QD‐LEDs) are demonstrated by employing the Zn x Cd 1‐ x S/ZnS core/shell QDs as emitters. The bright and efficient QD‐LEDs show a maximum luminance up to 4100 cd m −2 , and peak external quantum efficiency (EQE) of 3.8%, corresponding to 1.13 cd A −1 in luminous efficiency. Such high value of the peak EQE can be comparable with OLED technology. These results signify a remarkable progress, not only in the synthesis of high‐quality QDs but also in QD‐LEDs that offer a practicle platform for the realization of QD‐based violet‐blue display and lighting.