The varied magnetic polarons and related photoluminescence behaviors of layer PA ₂ CdCl ₄ : Fe(III) structures

Abstract Ferromagnetic polaron (FMP) coupling and antiferromagnetic polaron (AMP) coupling have been extensively studied in zero-dimensional and three-dimensional structures. However, studying their electronic structures and photophysical processes in layer structures still faces significant challenges. In this work, we synthesized minor and rich Fe ion-doped PA 2 CdCl 4 layer structures by slow-cooling crystallization and adjusting the Fe ion concentration. In minor Fe ion-doped PA 2 CdCl 4 , the Fe–Fe ion pair easily replaces the Cd–Cd pairs in the corner-sharing octahedra layer to form a FMP and promote a red emission (618 nm) from localized exciton-magnetic polarons (LEMPs). In the rich Fe ion doping, AMPs can be easily formed when Fe ions obtain electrons from NH 2 and convert into a low-spin state, coexisting with FMPs. The increasing number of AMPs promote the formation of a new Fe-aniline charge-transfer band; the co-work of AMPs and the Fe-aniline charge-transfer band result in a blue emission (466 nm). The result of the magnetic field-dependent photoluminescence (PL) measurement indicates that the population, energy and the spin direction of AMPs and FMPs can have a direct impact on the luminescence behavior of Fe ion-doped PA 2 CdCl 4 layered structures. The density functional theory (DFT) calculation result indicates that Fe–Fe pairs under ferromagnetic (FM) coupling interact via d x 2 – y 2 and d z 2 orbitals. Fe–Fe pairs under antiferromagnetic (AFM) coupling on the d xy and d z 2 orbitals. This work provides new insights into the varied magnetic polarons of layer structures and their effect on PL behavior.