Highly Water-Stable Polymer–Perovskite Nanocomposites

Abstract

The excellent performance of hybrid metal-halide perovskite nanocrystals (NCs) contrasts with their unsatisfactory stability in a high-humidity environment or water. Herein, polymer composite lead-halide perovskites (LHPs) NCs were prepared by casting or spin-coating to produce a high fluorescence yield and a fully water-resistant material. Poly(L-lactide) (PLla), polypropylene glycol (PPGly), and polysulfone (PSU) commercial polymers were used to prepare suspensions of MAPbBr 3 −HDA NCs (MA: CH 3 NH 3 ; HDA: hexadecylamine). The MAPbBr 3 −HDA@PLla suspension exhibited a maximum fluorescence quantum yield of 93% compared to 43% for the pristine MAPbBr 3 −HDA NCs. Strong emissions around 528 nm were also observed, with the same full width at half maximum value of 20 nm, demonstrating the successful fabrication of brightly luminescent LHP NCs@polymer combinations. Time-resolved photoluminescence measurements directly observed the enhanced spontaneous emission of the NCs induced by the polymeric environment. However, the cast films of MAPbBr 3 −HDA NCs mixed with PLla or PPGly did not resist water immersion. On the contrary, MAPbBr 3 −HDA@PPGly/PSU films containing well-dispersed ∼10 nm LHP NCs retained a bright green fluorescence emission even after 18 months under air conditions or water immersion up to 45 °C. From water contact angle measurements, profilometry, and X-ray photoelectron spectroscopy data, it could be assumed that the slightly hydrophobic PSU polymer is responsible for the high water stability of the fluorescent films, which avoids MAPbBr 3 −HDA NC degradation. This work shows that the LHP NC dispersion in dissolved commodity polymers holds great promise toward the long-term stability of LHP NC composites for the future development of wearable electronic devices and other waterproof applications.

Surface Restructuring of Zeolite‐Encapsulated Halide Perovskite to Activate Lattice Oxygen Oxidation for Water Electrolysis

“…It is worth mentioning that a molar ratio of 1.18:1 for Pb:Br was determined from XPS results (Figure S37a,b, Supporting Information) of the MAPbBr 3 @AlPO‐5 after OER stability testing, which also indicates that almost one‐third of the Br atoms were preserved when compared with the initial content; this result shows that the strong interactions between MAPbBr 3 NCs and AlPO‐5 matrices retain the perovskite at subsurface layers (where the dominant peak at 400.2 eV is assigned to the amine group in MA ions, Figure S37c, Supporting Information), resulting in excellent long‐term stability during water oxidation. [ 86 ] Additionally, after stability tests, Pb is partially found as Pb 4+ at the electrode surface, and the ratio of Pb 4+ :Pb 2+ is 0.4:1, validating the stable structure of MAPbBr 3 / α ‐PbO 2 . Notably, the outstanding electrocatalytic performance of the MAPbBr 3 @AlPO‐5 for overall water‐splitting is superior to those of recently reported non‐precious metal electrocatalysts (Figure 7E; Table S10, Supporting Information), [ 84 ] and given its superb stability, it holds great promise for practical applications.…”

Recent advances in synthesis of water-stable metal halide perovskites and photocatalytic applications

“…Polymer-based coating materials have several merits, such as solution processability, mechanical performance, and chemical functionalization. More importantly, polymers with abundant functional groups are good candidates to bond with surface ions of MHPs, improving both PLQYs and stability simultaneously 115–117 without compromising light absorption. 118 In addition, polymer matrices are capable of water uptake via water-induced swelling process 119 and thus alleviate the direct contact of water and MHPs to a degree.…”

Highly luminescent and stable CsPbBr3 perovskite nanocrystals coated with polyethersulfone for white light‐emitting diode applications

“…Generally, coating barrier materials on the surface of NCs is considered to be one of the most effective methods. To date, different kinds of barrier materials such as inorganic oxides [17], organic polymer [18][19][20] and metalorganic frameworks [21] were attempted. Among them, an organic polymer with excellent stability and structure tunability is regarded as an effective coating layer [19].…”