Comprehensive study on the impact of A-site cation engineering on crystallite growth, strain, and defect dynamics in lead bromide perovskite nanostructures and thin films

In this work, we present a comprehensive investigation of the structural and defect properties of hydrazinium (HA) substituted MAPbBr 3 perovskite nanoparticles and thin films. The incorporation of HA at the A-site was systematically examined to evaluate its influence on crystallite growth, lattice strain, dislocation density, stacking faults, and overall structural stability. X-ray diffraction (XRD) line profile analysis using Debye–Scherrer (DS), Monshi–Scherrer (MS), Williamson–Hall (WH), Size–Strain Plot (SSP), and Halder–Wagner (HW) methods revealed that HA substitution induces lattice expansion while maintaining the cubic phase, with thin films exhibiting larger crystallite sizes compared to nanoparticles. The incorporation of HA effectively reduced lattice strain, dislocation density, and stacking fault concentrations, resulting in enhanced crystallinity and structural stability. Among the applied models, the HW method provided the most reliable estimates due to its ability to account for strain effects.