PhD thesis defense: Engineering magnetic and optical properties in layered hybrid organic-inorganic metal-halide perovskites

 

Hybrid organic–inorganic perovskites (HOIPs) are versatile materials whose crystalline structure and chemical tunability enable direct correlations between composition, structure and physical properties. In particular, HOIPs based on metal and halides have become very relevant for optoelectronics, especially after the breakthrough of MAPbI₃ in 2009. However, growing environmental concerns have recently driven increased interest in Pb-free alternatives. Despite the potential of the latter, the influence of subtle chemical and structural variations on their physical behavior remains insufficiently understood. This thesis investigates the functional behavior of Pb-free metal-halide HOIPs through structural, magnetic, optical and chiroptical characterization across different families of compounds, employing XRD, Raman spectroscopy, VSM, PL and CD measurements. First, the influence of organic cations and perovskite phases on the magnetic properties of Cu²⁺, Mn²⁺ and Co²⁺ systems is examined, revealing tunable magnetic dimensionality and phenomena such as spin canting, spin-flop transitions and metamagnetism. The study then focuses on Mn²⁺ HOIPs, showing that variations in the organic cation modify the Mn²⁺ electronic environment and the magneto-optical response via magnetic polarons. Finally, chiral organic molecules are incorporated to introduce chiroptical functionality, with chiral Mn²⁺ HOIPs displaying robust chiral absorption and emission from bulk crystals down to exfoliated flakes. Overall, this work elucidates key parameters governing the magnetic, optical and chiroptical properties of metal-halide HOIPs and demonstrates that these functionalities can be chemically tailored, underscoring their potential for future Pb-free spintronic and optoelectronic devices.