Study of halide gradient formation via solution-solid halide exchange in crystalline CH\u3csub\u3e3\u3c/sub\u3eNH\u3csub\u3e3\u3c/sub\u3ePbBr\u3csub\u3e3\u3c/sub\u3e thin films

In this thesis, attempts have been made to understand halide exchange and mass transport inside the solid lattice of Lead Halide Perovskites (LHPs). We aim for the transformation of MAPbBr3 using ionic solutions including 1-Butyl-3-methylimidazolium iodide (BMIMI), and 1-Butyl-3-methylimidazolium chloride (BMIMCl) as halide ion sources to observe the halide diffusion across the thin film sample and to have LHPs with a gradient of mixed halides (MAPbBr3-x (I/Cl)x, 0 ≤ x ≤ 3). Successfully, MAPbBr3 single-crystalline thin film was fabricated with different configurations. Surface analysis of the LHPs, elemental composition, halide diffusion, roughness, and size of grains in our thin film was examined using a scanning electron microscope equipped with Energy-dispersive X-ray Spectroscopy (SEM-EDX), photoluminescence (PL), and Dektak-XT stylus surface profiling system. Advisor: Yinsheng Gu