Highly luminescent, multiply passivated green‐ and red‐light‐emitting quantum dots are used as color converters in InGaN blue LEDs to achieve external quantum efficiencies of 72% and 34%, respectively. White QD‐LEDs prepared for a display backlight are shown to have an efficacy of 41 lm W−1 and color reproducibility of 100% compared to the NTSC standard in CIE 1931. Finally, a 46 inch LCD TV panel (see image) using the QD‐LED backlight is successfully demonstrated for the first time.
There
is an urgent demand to improve the efficiency and the color purity
of the environment-friendly quantum dots (QDs), which can be used
in wide color gamut (WCG) displays. In this study, we optimized the
reaction conditions for the InP core synthesis and the ZnSe/ZnS multishell
growth on the core. As a result, remarkable improvements were achieved
in the photoluminescence quantum yield (PL QY, 95%) and the full width
at half-maximum (fwhm, 36 nm), with perfectly matched wavelength (528
nm) for the green color in WCG displays. Injection of the phosphorus
precursor at a mild temperature during the InP core synthesis reduced
the size distribution of the core to 12%, and the shell growth performed
at a high temperature significantly enhanced the crystallinity of
the thick passivating layer. We also investigated the photophysical
properties, particularly the energy trap distributions and trap state
emissions of the InP-based QDs with different shell structures. The
time-resolved and temperature-dependent PL spectra clearly indicated
that the well-passivated InP/ZnSe/ZnS QDs showed nearly trap-free
emissions over a wide temperature range (77–297 K). Also, the
on- and off-time probability on single QD blinking and Auger ionization
efficiencies also showed that these QDs were hardly affected by the
surface traps.
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