Synthetic History Matters: Understanding the Structure-Property Evolution in CsSnxGe1-xBr3 Perovskites

Abstract

Metal halide perovskites and related perovskite-inspired materials continue to attract attention for next-generation photovoltaic applications. Compositional synthetic design remains the preferred method for exploring property manipulation and for gaining new insights into material stability and behaviour. This study explores the CsSn_xGe_1−xBr₃ perovskite series to elucidate how composition and preparation method, including solvent, mechanochemical, and high-temperature synthesis, influence the chemical structure and optoelectronic properties. Various analytical techniques, including solid-state nuclear magnetic resonance (NMR) spectroscopy, nuclear quadrupole resonance (NQR) spectroscopy, powder X-ray diffraction (XRD), diffuse reflectance spectroscopy, and electron microscopy, have been employed to characterise the local atomic environment, long-range crystallographic structure, morphology, and optical properties of the produced CsSn_xGe_1−xBr₃ perovskites. NMR and NQR reveal unique chemical environments and electric field gradients, and how the atomic structure responds to different synthetic conditions across these perovskite materials. Paired with long-range diffraction and microscopy-based techniques, these methods provide detailed insight into crystallographic phase, B-site mixing, and domain formation across different compositions and syntheses.