Perovskite Anion Exchange: A Microdynamics Model and a Polar Adsorption Strategy for Precise Control of Luminescence Color

Abstract

Inorganic perovskite quantum dots (QDs) have natural advantages in the field of light-emitting diodes (LEDs) because of their high color purity and tunability in a wide range. However, when manufacturing efficiently mixedanion perovskite QDs (CsPbBr x I 3−x ) to meet the requirements of the pure red color standard in the display field (≈630 nm), results are difficult to control accurately due to the lack of exploration of its microscopic mechanism. Here, a microdynamics model is constructed for anion exchange dominated by vacancies which revealed the key role of polar solvent in reducing the surface energy barrier of anions through first-principle calculations. Besides, a polar solvent construct in situ anion exchange channels method is proposed. Then, the precise control of anion exchange is demonstrated, and the precise regulation spectrum of the whole red-light range (600-680 nm) is achieved. Finally, various QD LEDs (QLEDs) based on these tunable QDs are fabricated and exhibit excellent photoelectric performance in the main red range (620-680 nm). Among them, the champion QLEDs, have peak external quantum efficiency (EQE) of 16.3% at 633 nm and peak EQE of 18.2% at 646 nm, showing potential in meeting the requirements of display standard.

Enriched‐Bromine Surface State for Stable Sky‐Blue Spectrum Perovskite QLEDs With an EQE of 14.6%

“…[ 1–7 ] By virtue of tunable emission peaks across visible spectrum photoluminescence quantum yield (PLQY), narrow half‐width, wide color gamut (≈140%), and the high photoluminescence quantum yield, organic PeQD light‐emitting diodes (PeQLEDs) have attracted significant attention. [ 8–12 ] Recently, great breakthroughs have been achieved in the synthesis and performance of green‐ and red‐emitting PeQLEDs in recent years, [ 13–22 ] whereas the low performance of blue‐emitting PeQLEDs (wavelength range: 460–490 nm) impedes the development of commercial display applications for PeQLEDs. [ 23–27 ]…”

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performance of green-and red-emitting PeQLEDs in recent years, [13][14][15][16][17][18][19][20][21][22] whereas the low performance of blue-emitting PeQLEDs (wavelength range: 460-490 nm) impedes the development of commercial display applications for PeQLEDs. [23][24][25][26][27] The entire blue spectra are expected to be obtained by controlling the Br/Cl ratio in inorganic blue-emitting PeQDs (CsPb(Br x /Cl 1−x ) 3 ).

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Stable and large-scale organic–inorganic halide perovskite nanocrystal/polymer nanofiber films preparedviaa greenin situfiber spinning chemistry method

“…9 On the other hand, the slow decay τ 2 of the PAN/ MAPbBr 3 nanofiber film associated with the radiation composite is 262.64 ns, which is larger than that of MAPbBr 3 PNCs at 179.16 ns. 38 Therefore, it is clear that the PAN polymer in the PAN/MAPbBr 3 nanofiber film enhances the fluorescence lifetime of MAPbBr 3 . We speculated that the enhanced fluorescence lifetime may be attributed to the limited ion migration and energy transfer of MAPbBr 3 PNCs in the polymer matrix.…”

Anion Exchange in Cesium Lead Halide Perovskite Nanocrystals via Radiation Chemistry of Halohydrocarbons

“…Cesium lead halide (CsPbX 3 , X = Cl, Br, and I) perovskite nanocrystals (NCs) have attracted great attention due to their outstanding photoelectric properties and promising applications in illumination, photo­(electro)­catalysis, and solar cells. − Interestingly, CsPbX 3 NCs’ band gaps and thus optical and electrical properties can be modulated by adjusting the proportion of halide atoms (Cl, Br, and I), − which can be easily achieved by anion exchange in the postsynthesis process via mixing CsPbCl 3 , CsPbBr 3 , and CsPbI 3 NCs in appropriate ratios or mixing the solutions of NCs with halide anion precursors. − Many halide precursors have been utilized and investigated, including hydrohalic acids or halide gas precursors, , halide ammonium salts, ,,, trimethylsilyl halide reagents, , tetrafluoroborate halide salts, and inorganic metal halides. ,, Unfortunately, perovskite NCs are unstable in polar solvents. , These precursors for anion exchange and polar solvents needed for dissolving them, usually aliphatic alcohols or N , N -dimethylformamide (DMF), often cause decomposition or undesired deformation of perovskite NCs. Therefore, using inert halide precursors, for example, haloalkanes, is of high interest.…”