Effect of Mn–Mn Magnetic Ordering on Photoluminescence in 2D Layered Hybrid Perovskite (CH3NH3)2MnCl4

Abstract Charge and energy transfers among Mn 2+ ions determine the excited‐state dynamics in Mn 2+ ‐based phosphors, which modulate the luminescence properties in various applications. However, in crystals with dense Mn 2+ ions, luminescence is often quenched by antiferromagnetic interactions between adjacent Mn 2+ ions or electron‐phonon interactions, which lead to energy transfer to the defect states. Here, the modulation of photoluminescence by Mn–Mn magnetic ordering in a 2D layered hybrid perovskite (CH 3 NH 3 ) 2 MnCl 4 is reported. Specifically, antiferromagnetic ordering and spin flopping reduce the bright optical transitions from coupled Mn 2+ ions, whereas ferromagnetic ordering enhances the transitions. This magnetic effect competes with electron‐phonon interactions and determines the temperature‐ and magnetic‐field‐dependent photoluminescence, especially at low temperatures. This study not only enriches the understanding of the fundamental magneto‐optical properties of Mn 2+ ‐based perovskites but also provides new insights into the development of high‐performance lead‐free light‐emitting devices.