Pentavalent Manganese Luminescence: Designing Narrow-Band Near-Infrared Light-Emitting Diodes as Next-Generation Compact Light Sources

Abstract

Manganese in the pentavalent state (Mn 5+ ) is both rare and central in materials exhibiting narrow-band nearinfrared (NIR) emission and is highly sought after for phosphorconverted light-emitting diodes as promising candidates for future miniature solid-state NIR light source. We develop the Ca 14 Zn 6 Ga 10−x Mn x O 35 (x = 0.3, 0.5, 1.0, 1.25, 1.5, and 3.0) series that exhibit simultaneous Mn 4+ (650−750 nm) and Mn 5+ (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 Mn 4+ and Mn 5+ . 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 Mn 5+ luminescence and opens the way for the design of Mn 5+ -based narrow-band NIR phosphors.

Unraveling Luminescent Energy Transfer Pathways: Futuristic Approach of Miniature Shortwave Infrared Light-Emitting Diode Design

“…A shortwave infrared light (SWIR, 900–1700 nm) source in a compact size and operable with battery power is a critical need for delivering exciting answers to a wide range of spectroscopy, night surveillance, anticounterfeiting, solar cells, and bioimaging applications. − The phosphor-converted light-emitting diode (pc-LED) based on energy downshifting converter technology has been pursued as a promising energy device for infrared light and also an alternative to the well-known conventional SWIR light devices. , For example, pc-white LEDs have already revolutionized lighting and backlighting technologies by saving energy and trimming the device size, , and pc-LED devices based on Cr 3+ - and Eu 2+ -activated inorganic phosphors can emit near-infrared light around 600–1100 nm. − Obtaining emissions beyond 1100 nm using Cr 3+ , Bi 3+ , or Eu 2+ is difficult, while La 3 Ga 5 GeO 14 :Cr 3+ is the only reported super broadband (650–1200 nm) near-infrared phosphor, and its practical applications are limited. ,,, Thus, the development of SWIR-emitting luminous inorganic phosphors is a vital and urgent task.…”

Evaluation of Li2SnO3:Cr3+, Mn4+ as a dual-emitter luminescence sensor for cryogenic temperatures

“…Specifically, the EPR line with g eff = 1.999 can be attributed to the Mn 4+ ion while the lines with g eff = 3.649 and g eff = 1.38 are characteristic of Cr 3+ ions within an octahedral environment; notably these two EPR lines corresponds to a single Cr 3+ centre, 24 . 25 As temperature drops, the components of the EPR lines originating from Cr 3+ ions become more discernible along with the hyperfine interactions of Mn 4+ ions. To delve further into ion symmetry, we selected the lowest temperature of T = 80 K as this provides a clearer understanding of the structural arrangement of the ions in question.…”

Sharp-Line Near-Infrared Emission from Tetrahedron-Occupied Ni2+ in Ca2GeO4

“…Recently, pentavalent manganese has emerged as a brand-new NIR-II emitter for a luminescent thermometer and deep-issue imaging. , Mn 5+ has the 3 d 2 electron configuration, in which the 3 A 2 ground state is non-degenerate, while the first excited state 1 E could be influenced by the nephelauxetic effect. Therefore, when located in a tetrahedrally coordinated site with a strong crystal field, Mn 5+ exhibits a sharp-peak NIR-II emission of spin-forbidden 1 E– 3 A 2 transition (fwhm < 10 nm, λ em = 1100–1200 nm) .…”