Semitransparent quantum dot light-emitting diodes by cadmium-free colloidal quantum dots

• Published in: Journal of nanoscience and nanotechnology Vol. 14; no. 11; p. 8636
• Main Authors: Kim, Yohan, Ippen, Christian, Greco, Tonino, Oh, Min Suk, Chul, Jong Han, Lee, Jeongno, Wedel, Armin, Kim, Jiwan
• Format: Journal Article
• Language: English
• Published: United States 01.11.2014
• ISSN: 1533-4899
• DOI: 10.1166/jnn.2014.9975

The InP/ZnSe/ZnS multishell colloidal quantum dots (QDs) were prepared by convenient heating-up method for an emission layer of semitransparent quantum dot light-emitting diodes (QD-LEDs). The synthesized InP/ZnSe/ZnS multishell QDs exhibited an emission peak at 545 nm for clear green color with a full-width at half-maximum (FWHM) of 50 nm, and photoluminescent (PL) quantum yield (QY) of 45%. The multishell on the indium phosphide (InP) core helped increasing QY and stability by reducing interfacial defects. Using a Ca/Ag cathode, the whole QD-LEDs were semitransparent throughout the visible wavelengths. The maximum brightness and currernt efficiency of semitransparent QD-LEDs reached 587 cd/m2 and 1.52 cd/A by controlling the thickness of Ca/Ag cathode, which is comparable to the device with opaque LiF/Al cathode (1444 cd/m2 and 1.98 cd/A). The performance of our semitransparent and eco-friendly device is not matched with traditional cadmium (Cd) based QD-LEDs yet, but it shows the great potential for various window-type information displays.