Crystal Structure of Individual CsPbBr₃ Perovskite Nanocubes

Abstract

The atomic structure\nof CsPbBr₃ nanocubes (NCs) was studied at the single-particle\nlevel via a high-resolution transmission electron microscopy (HRTEM)\ndefocus-series analysis. The technique entails acquiring lattice-resolved\nHRTEM images of individual NCs over progressive defocus values. CsPbBr₃ NC atomic structure was evaluated by comparing acquired experimental\ndata to simulated lattice-resolved images and corresponding Fourier\ntransform patterns of both orthorhombic (<i>Pnma</i>) and\ncubic (<i>Pm</i>3̅m) CsPbBr₃ polymorphs.\nHerein, CsPbBr₃ NCs with average edge lengths (<i>l</i>) of <i>l</i> ∼ 10 and 5 nm are analyzed\nusing the aforementioned technique. In the former, we find evidence\nfor the coexistence of both cubic and orthorhombic lattices. In the\nlatter, solely cubic character is observed, illustrating a potential\nsize dependency to the crystal symmetry of CsPbBr₃ NCs.\nSuch structural measurements provide critical insight into elucidating\nthe structure/(optical and electrical) function relationship of CsPbBr₃ NCs.