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

Abstract

Charge and energy transfers among Mn2+ ions determine the excited-state dynamics in Mn2+-based phosphors, which modulate the luminescence properties in various applications. However, in crystals with dense Mn2+ ions, luminescence is often quenched by antiferromagnetic interactions between adjacent Mn2+ 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 (CH3NH3)2MnCl4 is reported. Specifically, antiferromagnetic ordering and spin flopping reduce the bright optical transitions from coupled Mn2+ 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 Mn2+-based perovskites but also provides new insights into the development of high-performance lead-free light-emitting devices.