Highly Stable, New, Organic-Inorganic Perovskite (CH₃ NH₃ )₂ PdBr₄ : Synthesis, Structure, and Physical Properties

Lead halide perovskites have attracted striking attention recently, due to their appealing properties. However, toxicity and stability are two main factors restricting their application. In this work, a less toxic and highly stable Pd-based hybrid perovskite was experimentally synthesized, after exploring different experimental conditions. This new hybrid organic-inorganic perovskite (CH₃ NH₃ )₂ PdBr₄ was found to be an orthorhombic crystal (Cmce, Z=4) with lattice parameters a=8.00, b=7.99, c=18.89 Å. The Cmce symmetry and lattice parameters were confirmed using Pawley refinement and the atoms positions were confirmed based on DFT calculation. This perovskite compound was determined to be a p-type semiconductor, with a resistivity of 102.9 kΩ cm, a carrier concentration of 3.4 ×10¹²  cm^-3 , and a mobility of 23.4 cm²  (V s)^-1 . Interestingly, XRD and UV/Vis measurements indicated that the phase of this new perovskite was maintained with an optical gap of 1.91 eV after leaving in air with a high humidity of 60 % for 4 days, and unchanged for months in N₂ atmosphere; much more stable than most existing organic-inorganic perovskites. The synthesis and various characterizations of this work further the understanding of this (CH₃ NH₃ )₂ PdBr₄ organic-inorganic hybrid perovskite material.