Surface morphology modulation in chlorine-doped diisopropylammonium bromide film via Cl-induced domain refinement

Diisopropylammonium bromide (DIPAB) has great potential in the field of flexible electronics. However, its room temperature ferroelectricity needs thermal treatment above the irreversible phase-transition temperature (T₁), which limits its application. Therefore, chlorine-doped DIPAB (DIPAB-C, C₆H₁₆NBr_1-x Cl _x ) was prepared by spin-coating in this study. XPS confirmed successful Cl incorporation into DIPAB. DSC revealed that Cl doping significantly reduces the T₁ by up to 41°C, expanding the ferroelectric phase stability window. This doping-induced phase evolution was further confirmed by temperature-dependent XRD analysis. PFM was employed to confirm the ferroelectricity of the DIPAB-C film. XRD and EDS systematically indicated intensified lattice distortion and elemental distribution with increasing doping concentration. Polarized light microscopy (PLM) observations showed Cl doping reduces domain width from 100 μm to 3 μm, substantially enhancing domain wall density. This domain-dominated surface engineering provides a strategy for concurrent manipulation of microstructures and thermal stability in molecular ferroelectrics.