High-efficiency blue and white electroluminescent devices based on non-Cd I−III−VI quantum dots

• Published in: Nano energy Vol. 63; p. 103869
• Main Authors: Yoon, Suk-Young, Kim, Jong-Hoon, Kim, Kyung-Hye, Han, Chang-Yeol, Jo, Jung-Ho, Jo, Dae-Yeon, Hong, Seungki, Hwang, Jun Yeon, Do, Young Rag, Yang, Heesun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2019
• Subjects: Bicolored; High-efficiency; Non-Cd quantum dots; White electroluminescence; White electroluminescence; High-efficiency; Bicolored; Non-Cd quantum dots
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2019.103869

Research direction of colloidal quantum dot (QD)-based LEDs (QLEDs), whose performance has substantially progressed over last two decades, has been oriented mostly to the fabrication of next-generation, high-color gamut display devices particularly based on Cd-containing QDs, while their extension to solid-state planar lighting application remains nearly unexplored. In this work, we report on all-solution-processed fabrication of group I–III–VI chalcogenide, non-Cd QDs-based high-efficiency white lighting electroluminescent (EL) devices. For this, using Zn–Cu–Ga–S (ZCGS) QD emitters having a high photoluminescence quantum yield (PL QY) of 80% a multilayered blue QLED consisting of poly(9-vinylcarbazole) hole transport layer (HTL) and Mg-alloyed ZnO nanoparticle electron transport layer (ETL) is first fabricated, showing a maximum external quantum efficiency (EQE) of 7.1%. Then, white QLEDs containing a mixture of blue ZCGS and yellow Cu–In–S QDs as a single emitting layer (EML) are constructed with the same HTL/ETL combination as above. White EL spectral distribution is facilely tunable simply by varying ZCGS-to-CIS QD content ratio in the EML of white EL device. The optimum white QLED not only generates the peak quantities of 2172 cd/m2 in luminance and 4.6% in EQE, corresponding to the record values ever reported in non-Cd white EL devices, but exhibits high color rendering index up to 82. [Display omitted] •Highly fluorescent non-Cd I−III−VI emitters of blue ZCGS and yellow CIS QDs were synthesized.•ZCGS QD-based blue EL device yielded the maximum EQE of 7.1%.•Bichromatic white QLED integrated purely with I−III−VI QD emitters exhibited the maximum EQE of 4.6%.