Chemical Group Substitution Enables Highly Efficient Mn⁴⁺Luminescence in Heterovalent Systems

Abstract

detection due to their rich and tunable luminescence properties. [1][2][3][4] To obtain high luminescence efficiency, the activator ions are commonly introduced into the equivalent cationic site to avoid the generation of charge compensation defects (i.e., quenching sites), where the excitation energy is lost non-radiatively (as heat). [5][6][7] On the other hand, as evidenced by many types of research, the incorporation of activators into a heterovalent site can also be regarded as a powerful approach to developing a high-performance phosphor, namely the heterovalent doping scheme. [8][9][10][11] Compared with the equivalent doping, heterovalent doping can induce some abnormal local environments around the activators, leading to the emergence of new fascinating luminescent properties (e.g., new emission band, zero thermal quenching, and shortened fluorescence lifetimes). [12][13][14] However, the inevitable co-existence of defects to maintain the charge balance is detrimental to the overall performance of phosphors, particularly in terms of quantum efficiencies (QEs). Therefore, the design principle to avoid the generation of charge compensation defects is urgently required for the heterovalent doping phosphors.Mn 4+ -doped fluoride phosphors have received enormous attention in display and lighting due to the broadband

A Na2MoO2F4:Mn4+ phosphor with red luminescence peaking at 625 nm and a ZPL/v6 intensity ratio of 243%

“…35 The severe thermal quenching could possibly be attributed to the larger ionic radius of Mo 6+ compared to Mn 4+ , resulting in a reduction of the structural rigidity, enhanced non-radiative transitions, while the presence of defects simultaneously hinders the transfer of energy to the next luminescence center. 35–38…”

“…35 The severe thermal quenching could possibly be attributed to the larger ionic radius of Mo 6+ compared to Mn 4+ , resulting in a reduction of the structural rigidity, enhanced non-radiative transitions, while the presence of defects simultaneously hinders the transfer of energy to the next luminescence center. [35][36][37][38] The Tanabe-Sugano diagram illustrates the effect of the octahedral crystal field where the 3d 3 electrons of Mn 4+ are located on each of the energy levels (Fig. 5(c)).…”

Exploring dual-emission properties in Mn4+ distinctively activated BaTaF7 red emitting phosphor

“…During liquid-phase synthesis, Mn 4+ forms MnF 6 2− anionic groups instead of ions, leading to group substitution, as seen in various examples like Mn 4+ -doped Rb 2 MoO 2 F 4 , 29 (TMA) 2 XF 6 (X = Ge, Ti, Zr), 38 (TMA) 2 WO 2 F 4 , 39 and (TMA) 2 MoO 2 F 4 . 39 Mn 4+ ions maintain v 6 , v 4 , and v 3 vibrational modes in an octahedral environment, producing characteristic emission peaks, indicating that Mn remains in an octahedral environment in our work. Therefore, DFT calculations were utilized to investigate the nature of Mn 4+ dopant substitution in BaTaF 7 further.…”

Optical enhancement of highly efficient organic–inorganic oxyfluoride red phosphors via the cation co-doping strategy

“…Nowadays, luminescent materials based on lanthanide or transition metal ion activation have been used as stable and effective inorganic luminescent materials in the fields of lighting, displays, information security and information storage. 1–6 Typically, Mn 4+ activated red phosphors, due to their inherent d–d transition, have long been used as effective luminescent centers, with strong excitation bands in the ultraviolet and blue regions. 4–7 They are ideal for many applications, including warm WLED lighting, indoor plant cultivation, backlighting, and information security.…”

“…1–6 Typically, Mn 4+ activated red phosphors, due to their inherent d–d transition, have long been used as effective luminescent centers, with strong excitation bands in the ultraviolet and blue regions. 4–7 They are ideal for many applications, including warm WLED lighting, indoor plant cultivation, backlighting, and information security. For warm white lighting and backlighting, appropriate excitation/emission wavelengths, remarkable luminescence intensity, high quantum efficiency (QE) and excellent thermal/chemical stability are particularly important.…”