Mapping of Perovskite Nanocrystal Assemblies Inside Nanoarchitected Membranes with Scanning SAXS and Micro-PL

Abstract Three-dimensional nanoarchitected materials provide tunable confined environments for organizing colloidal nanocrystals. However, little is known about how nanocrystals organize inside them across extended areas. Here, we map the infilling of CsPbBr3 nanocrystals within nanoarchitected SU-8 sheets of around 30 μm thickness with a characteristic pore size of ∼500 nm across millimeter-scale areas. Nanocrystals dispersed in hexane or toluene were deposited into these uncoated and TiO2-coated nanoarchitected materials. Scanning small-angle X-ray scattering (scanning SAXS) resolved nanometer-scale packing across the material, while microphotoluminescence (micro-PL) mapped the corresponding optical response. Hexane produced comparatively uniform nanocrystal-nanocrystal spacing with broad SAXS features, indicating weak structural order. In contrast, toluene produced narrower diffraction features and, in the TiO2-coated material, a radial gradient in nanocrystal-nanocrystal spacing. A correlated PL shift supported the assignment of this gradient to nanocrystal size segregation. Measurements of the uncoated material further showed that wall chemistry modifies the spatial nanocrystal packing pattern. By enabling millimeter-scale mapping of nanometer-scale organization, this approach reveals how solvent choice influences nanocrystal packing and highlights the importance of multimodal mapping for understanding complex nanomaterials for emerging applications.