Abstract
Semiconductor quantum dots (QDs) are a promising luminescent phosphor for next-generation lightings and displays. In particular, QD-based white light-emitting diodes (WLEDs) are considered to be the candidate light sources with the most potential for application in displays. In this work, we synthesized quaternary/ternary core/shell alloyed CdZnSeS/ZnSeS QDs with high bright emission intensity. The QDs show good thermal stability by performing high temperature-dependent experiments that range from 295 to 433 K. Finally, the WLED based on the CdZnSeS/ZnSeS QDs exhibits a luminous efficiency (LE) of 28.14 lm/W, an external quantum efficiency (EQE) of 14.86%, and a warm bright sunlight close to the spectrum of daylight (Commission Internationale de l'éclairage (CIE) coordinates 0.305, 0.371). Moreover, the photoluminescence (PL) intensity, LE, EQE, and correlated color temperature (CCT) of as-prepared QD WLED remained relatively stable with only slight changes in the luminescence stability experiment.
Highlights
Semiconductor quantum dots (QDs) have shown emerging significant promise as solid-state lightings and displays (Li et al, 2020; Zvaigzne et al, 2020), sensors (Koeppel et al, 2007; Liang et al, 2021), biomedicine (Zvaigzne et al, 2016; Pashazadeh-Panahi and Hasanzadeh, 2019), biological labeling (Bai et al, 2020), solar cell (Xu T. et al, 2021; Ostadebrahim and Dehghani, 2021), and laser physics (Nautiyal et al, 2021; Tsuji et al, 2021) owing to their superior optoelectronic properties such as high photoluminescence (PL) quantum yield (QY) (PLQY), narrow emission bandwidth, size-controlled tunable emission wavelength, and high photochemical stability and durability (Zhang et al, 2015; Li Q. et al, 2016; Harris et al, 2016; Leach and Macdonald, 2016; Giansante and Infante, 2017; Owen and Brus, 2017; Ghosh and Manna, 2018)
We demonstrate the superior optical properties of quaternary/ ternary alloyed CdZnSeS/ZnSeS QDs and show the prospect as white light-emitting diodes (WLEDs) luminescent material
Long time operation of the QD WLED at a stable voltage of 3 V reveals that the external quantum efficiency (EQE) increased from a maximum of 6.81% to 6.85%, which only increased by 0.5% (Figure 6B)
Summary
Semiconductor quantum dots (QDs) have shown emerging significant promise as solid-state lightings and displays (Li et al, 2020; Zvaigzne et al, 2020), sensors (Koeppel et al, 2007; Liang et al, 2021), biomedicine (Zvaigzne et al, 2016; Pashazadeh-Panahi and Hasanzadeh, 2019), biological labeling (Bai et al, 2020), solar cell (Xu T. et al, 2021; Ostadebrahim and Dehghani, 2021), and laser physics (Nautiyal et al, 2021; Tsuji et al, 2021) owing to their superior optoelectronic properties such as high photoluminescence (PL) quantum yield (QY) (PLQY), narrow emission bandwidth, size-controlled tunable emission wavelength, and high photochemical stability and durability (Zhang et al, 2015; Li Q. et al, 2016; Harris et al, 2016; Leach and Macdonald, 2016; Giansante and Infante, 2017; Owen and Brus, 2017; Ghosh and Manna, 2018). The emission peaks of the ternary CdZnS or CdZnSe QDs are limited from 400 to 620 nm, which restricts them from achieving high color rendering index (CRI) for a white LED (WLED). The quaternary/ternary alloyed CdZnSeS/ZnSeS QDs with two different emission colors were synthesized by the thermal injection method. The WLED based on the prepared CdZnSeS/ZnSeS QDs exhibits excellent optical performances and high luminous stability. We demonstrate the superior optical properties of quaternary/ ternary alloyed CdZnSeS/ZnSeS QDs and show the prospect as WLED luminescent material. The solutions were taken at different times to record UV–Vis absorption and PL emission spectra of the QDs. After the alloyed core QDs were achieved, a solution of ZnO, S/TOP, and Se/TOP precursors was added swiftly for the overcoating of the ternary ZnSeS shell layer. The PLQY, luminous efficiency (LE), external quantum efficiency (EQE), emission spectrum, correlated color temperature (CCT), and Commission Internationale de l’éclairage (CIE) of QD WLED were studied systematically
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