Pentavalent Manganese Luminescence: Designing Narrow-Band Near-Infrared Light-Emitting Diodes as Next-Generation Compact Light Sources
Veeramani Rajendran, Kuan‐Chun Chen, Wen‐Tse Huang, Natalia Majewska, Tadeusz Leśniewski, Maciej Grzegorczyk, Sebastian Mahlik, Grzegorz Leniec, S.M. Kaczmarek, Wei Kong Pang, Vanessa K. Peterson, Kuang‐Mao Lu, Ho Chang, Ru‐Shi Liu
Abstract
Manganese in the pentavalent state (Mn5+) is both rare and central in materials exhibiting narrow-band near-infrared (NIR) emission and is highly sought after for phosphor-converted light-emitting diodes as promising candidates for future miniature solid-state NIR light source. We develop the Ca14Zn6Ga10-xMnxO35 (x = 0.3, 0.5, 1.0, 1.25, 1.5, and 3.0) series that exhibit simultaneous Mn4+ (650-750 nm) and Mn5+ (1100-1250 nm) luminescence. We reveal a preferential occupancy of Mn in regular octahedral and tetrahedral environments, with the short bond length between these responsible for luminescence. We present a theoretical spin-orbital interaction model in which breaking the spin selection rule permits the luminescence of Mn4+ and Mn5+. A total photon flux of 87.5 mW under a 7 mA driving current demonstrates its potential for real-time application. This work pushes our understanding of achieving Mn5+ luminescence and opens the way for the design of Mn5+-based narrow-band NIR phosphors.