The use of sterically hindered N,N′-diisopropylbenzene-1,2-diamine (DIBA) for aminophosphine-based InP QDs synthesis in an oleylamine (OLAm) medium is evidenced as a powerful tool to finely control their size in a reproducible way. This diamine forms in situ a P(DIBA)(OLAm) species accounting for the observed size-tuning effect because the QDs crystallize as tetrahedra with an edge length (3.5 to 6.6 nm) depending on the DIBA concentration (0 to 7 eq./indium). This kinetically controlled size-tuning mechanism is proposed by combining 31 P NMR and UV−vis spectroscopy. A proof-of-concept is established by coating the InP cores with ZnS shells. The luminescence of the as-synthesized InP/ZnS QDs is tunable over the 480−620 nm range, with photoluminescence internal quantum efficiencies of 45 to 60% suitable for applications as phosphors in LED lighting systems and LED displays.
The architecture of Zn‐Al layered double hydroxides (LDHs), organo‐modified with bola‐amphiphiles molecules, is matching its interlayer space to the size of narrow‐band red‐emitting InP/ZnS core–shell quantum dots (QDs) to form original high‐performance functional organic–inorganic QD‐bola‐LDH hybrids. The success of size‐matching interlayer space (SMIS) approach is confirmed by X‐ray diffraction, small angle X‐ray scattering (SAXS), TEM, STEM‐HAADF, and photoluminescence investigations. The QD‐Bola‐LDH hybrid exhibits a photoluminescence quantum yield three times higher than that of pristine InP/ZnS QDs and provides an easy dispersion into silicone‐based resins, what makes the SMIS approach a change of paradigm compared to intercalation chemistry using common host structures. Moreover, this novel hybrid presents low QD–QD energy transfer comparable to that obtained for QDs in suspension. Composite silicone films incorporating InP/ZnS (0.27 wt%) QD‐bola‐LDH hybrids further show remarkable improved photostability relative to pristine QDs. An LED overlay consisting of a blue LED chip and silicone films loaded with QD‐bola‐LDH hybrids and YAG:Ce phosphors exhibits a color rendering index close to 94.
Over the last decade, upconversion nanoparticles (UCNP) have been widely investigated in nanomedicine due to their high potential as imaging agents in the near-infrared (NIR) optical window of biological tissues....
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