A new three-step photo-oxidative degradation mechanism of MAPbI3 is proposed. A strategy for protecting MAPbI3 by 2-(4-fluorophenyl)propan-2-amine modification is designed.
In
recent years, lead halide perovskite nanocrystals (NCs) have
attracted significant attention in both fundamental research and commercial
applications because of their excellent optical and optoelectrical
properties. However, the protective ligands on the surface of the
perovskite NCs could be easily removed after the tedious process of
centrifugation, separation, and dispersion, which greatly hampers
their stability against light, heat, moisture, and oxygen and limits
their practical applications. Here, we report a new post-processing
free strategy (i.e., without centrifugation, separation, and dispersion
process) of using an ultraviolet (UV)-polymerizable acrylic monomer
of lauryl methacrylate as the solvent to synthesize CsPbBr3 NCs, and then adding polyester polyurethane acrylate oligomer, monomer
(IBOA), and initiator for direct UV polymerization to fabricate NC–polymer
composite films. These films exhibited an improved photoluminescence
quantum yield (85–90%) than classic NC films (40–50%),
which were processed using octadecene (ODE) as the solvent for NC
synthesis and postprocessed for UV polymerization. Significantly,
the as-fabricated films by post-processing free strategy exhibited
excellent photostability against strong Xe lamp illumination; while
the other films using classic methods were quickly photodegraded.
Meanwhile, these NC–polymer composite films showed good stability
against moisture and heating when aging in water at 50 °C for
over 200 h. These films, along with K2SiF6:Mn4+ (KSF) phosphor emitters, were used as downconverters for
blue light-emitting diodes in liquid-crystal displays with a wide
color gamut of 115% in the International Commission on Illumination
(CIE) 1931 color space. This work provides a facile and effective
strategy for the preparation of ultrastable and bright color-conversion
NC films for the development of the next-generation wide color gamut
displays.
The attempts to mediate iterative RAFT polymerization of ionic monomers through visible light irradiation in water at 20 °C is reported, in which complete conversions are attained in several tens of minutes and the propagation suspends/restarts immediately for multiple times on cycling irradiation. This technique suits the one-pot synthesis of NH2 /imidazole-based polymers with tuned structures from homo to random, block, random-block, and block-random-block, thus is robust and promising to control the sequence of the ionized water-soluble reactive copolymers.
A novel triphenylphosphine (TPP) treatment strategy was developed to prepare the near‐infrared emission CsPbI3 nanocrystal (NC)‐polymer composite thin‐film luminescent solar concentrators (LSCs) featuring high absolute photoluminescence quantum yield (PLQY), low reabsorption, and high stability. The PL emission of the LSCs is centered at about 700 nm with 99.4±0.4 % PLQY and narrow full width at half maximum (FWHM) of 75 meV (30 nm). Compared with LSCs prepared with classic CsPbI3 NCs, the stability of the LSCs after TPP treatments has been greatly improved, even after long‐term (30 days) immersion in water and strong mercury‐lamp irradiation (50 mW cm−2). Owing to the presence of lone‐pair electrons on the phosphorus atom, TPP is also used as a photoinitiator, with higher efficiency than other common photoinitiators. Large‐area (ca. 75 cm2) infrared LSCs were achieved with a high optical conversion efficiency of 3.1 % at a geometric factor of 10.
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