Despite the exceptional optoelectronic characteristics of the emergent perovskite nanocrystals, the ionic nature greatly limits their stability, and thus restricts their potential applications. Here we have adapted a self-assembly strategy to access a rarely reported nanorod suprastructure that provide excellent encapsulation of perovskite nanocrystals by polymer-grafted graphene oxide layers. Polyacrylic acid-grafted graphene oxide (GO-g-PAA) was used as a surface ligand during the synthesis of the CsPbX perovskite nanocrystals (NCs), yielding particles (5-12 nm) with tunable halide compositions that were homogeneously embedded in the GO-g-PAA matrix. The resulting NC-GO-g-PAA exhibits a higher photoluminescence quantum yield than previously reported encapsulated NCs while maintaining an easily tunable bandgap, allowing for emission spanning the visible spectrum. The NC-GO-g-PAA hybrid further self-assembles into well-defined nanorods upon solvent treatment. The resulting nanorod morphology imparts extraordinary chemical stability toward protic solvents such as methanol and water and much enhanced thermal stability. The introduction of barrier layers by embedding the perovskite NCs in the GO-g-PAA matrix, together with its unique assembly into nanorods, provides a novel strategy to afford robust perovskite emissive materials with environmental stability that may meet or exceed the requirement for optoelectronic applications.

Creating highly stable inorganic perovskite nanocrystals (CsPbX 3 , X=Cl, Br and I) with excellent optical performance is challenging because their optical properties depend on their ionic structure and its inherent defects. Here, we present a facile and effective synthesis using a nano confinement strategy to grow Mn 2+ doped CsPbCl 3 nanocrystals embedded in dendritic mesoporous silica nanospheres (MSNs). The resulting nanocomposite is abbreviated as Cs(Pb x /Mn 1x)Cl 3 @MSNs and can serve as the orange emitter for white lightemitting diodes (WLED). The MSN matrix was prepared via a templated solgel technique as monodispersed centerradial dendritic porous particles, with a diamater of around 105 nm and an inner pore size of around 13 nm. The MSN was then utilized as the matrix to initiate the growth of Mndoped perovskite nanocrystals (NCs). The NCs in the resulting composite have an average diameter of 8 nm and a photoluminescence quantum yield (PLQY) exceeding 30%. In addition, the optical properties of the Cs(Pb x /Mn 1x)Cl 3 @MSNs composite can be tuned by varying the Mn 2+ doping level. The resulting composites presented a significantly improved resistance to UV light, temperature, and moisture compared to the bare Cs(Pb 0.72 /Mn 0.28)Cl 3. Finally, we fabricated downconverting white light emitting diodes (WLEDs) by using Cs(Pb x /Mn 1x)Cl 3 @MSNs composite as the orangeemitting phosphor deposited onto UV emitting chips, demonstrating their promising applications in solidstate lighting. This work provides a valuable approach to fabricate stable orange luminophores as replacements for traditional emitters in LED devices.

Spiro[fluorene-9,9′-xanthene]-based hole transporting materials functionalized with four-armed arylamine moieties located at different positions are synthesized for perovskite solar cells.

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