Water-Triggered Transformation of Ligand-Free Lead Halide Perovskite Nanocrystal-Embedded Pb(OH)Br with Ultrahigh Stability

Abstract

Lead halide perovskite (LHP) nanomaterials have attracted tremendous attention owing to their remarkable optoelectronic properties. However, they are extremely unstable under moist environments, high temperatures, and light illumination due to their intrinsic structural lability, which has been the critical unsolved problem for practical applications. To address this issue, we propose a facile and environmentally friendly ligand-free approach to design and synthesize rod-like CsPb 2 Br 5 -embedded Pb(OH)Br with excellent stability under various harsh environments such as soaking in water, heating, and ultraviolet (UV) illumination. Plate-like CsPbBr 3 -and Cs 4 PbBr 6 -embedded Pb(OH)Br powders are first formed by evaporating the solvent in a dispersion of ethanol (or methanol, isopropanol), Cs 2 CO 3 , and PbBr 2 . Upon soaking in water, the plate-like sample undergoes phase transformation from CsPbBr 3 and Cs 4 PbBr 6 to CsPb 2 Br 5 and shape conversion from nanoplate to a microrod, leading to the formation of rod-like CsPb 2 Br 5 -embedded Pb(OH)Br. The stable Pb(OH)Br coating effectively prevents the luminescent CsPb 2 Br 5 nanocrystals from reacting with water, leading to extremely high aqueous stability of the CsPb 2 Br 5 -embedded Pb(OH)Br. The photoluminescence (PL) intensity of the representative CsPb 2 Br 5 -embedded Pb(OH)Br sample can maintain 92.2% of the initial PL intensity value even after soaking in room-temperature water for 165 days; in the meantime, the phase and shape are preserved. The typical sample also shows outstanding stability under hot water, UV illumination, and annealing conditions. The ultrahigh aqueous stability, thermal stability, and photostability of the CsPb 2 Br 5 -embedded Pb(OH)Br nanomaterials suggest an effective, facile, and environmentally friendly technique to grow perovskite-based nanomaterials for promising practical applications in the optoelectronic field.

Integration of Highly Luminescent Lead Halide Perovskite Nanocrystals on Transparent Lead Halide Nanowire Waveguides through Morphological Transformation and Spontaneous Growth in Water

“…CsPb 2 Br 5 platelets were first synthesized using the same method as before by simply dropping CsPbBr 3 micro-cubes (or powders) in a large quantity of pure water (>20 times in mass) in a flask or bottle at room temperature. [27] Similar watertriggered phase transformation has also been reported, [44][45][46][47][48] the transformation is due to a high solubility of CsPbBr 3 and a much lower solubility of CsPb 2 Br 5 in water, CsPb 2 Br 5 can be formed in seconds and become a white precipitate from the initial yellow CsPbBr 3 powders. This rapid structural conversion in water can be verified by in situ Raman spectroscopy.…”

CsPbBr3@SiO2 Core–Shell Nanoparticle Films for Superhydrophobic Coatings

“…55 It is noteworthy that the formation of the Pb(OH)Br layer can effectively stabilize perovskite-based nanomaterials. 55,56 In the meantime, the surface morphology preserved the hierarchical and porous structure (Figure S14 in the Supporting Information), and surface wettability maintained superhydrophobicity (inset of Figure 5a). These analyses indicate that the interesting enhancement of PL performances and the long-term stability in the ambient environment are due to the synergetic contribution from phase conversion, protection by SiO 2 , and surface modification by methyl groups.…”

“…The transformation from CsPbBr 3 to CsPb 2 Br 5 is due to the very slow reaction of CsPbBr 3 with water molecules in the ambient environment. This proposed mechanism can be supported by the previously reported phase conversion from the as-synthesized CsPbBr 3 sample to the CsPb 2 Br 5 phase either through water vapor treatment or directly soaking CsPbBr 3 - and Cs 4 PbBr 6 -based nanoplates in water . It is noteworthy that the formation of the Pb­(OH)­Br layer can effectively stabilize perovskite-based nanomaterials. , In the meantime, the surface morphology preserved the hierarchical and porous structure (Figure S14 in the Supporting Information), and surface wettability maintained superhydrophobicity (inset of Figure a).…”

Hexamethyldisilazane-assisted Mn2+ doping of perovskite nanocrystals under ambient conditions

“…Lead halide perovskite (LHP) nanomaterials have attracted widespread attention in optoelectronic fields such as light-emitting diodes (LEDs), 1–3 lasers, 4 luminescent solar concentrators 5 and photodetectors 6 due to their many advantages, such as high photoluminescence quantum yield (PLQY), large carrier mobility, narrow full width at half maxima (FWHM), high light absorption coefficient and tunable bandgap. 7–9 However, the toxic Pb 2+ ion component and the intrinsic poor stability against oxygen, moisture, light irradiation, etc.…”