Efficient red and broadband near‐infrared luminescence in Mn²⁺/Yb³⁺‐doped phosphate phosphor

Abstract

Nowadays, human beings are facing the challenge of deteriorating natural environment and depleting resources with the rapid growth of population and the advancement of modernization process. The exploration of energy-saving and environment-friendly technologies and the development of advanced functional materials are expected to alleviate this crisis. [1][2][3][4] Recently, pc-WLEDs have attracted extensive attention as a new generation of solid-state lighting equipment, which is displacing the traditional incandescent, mercury, and fluorescent lamps due to their advantages of low energy consumption, high efficiency, environment friendly, and long service time. [5][6][7][8][9][10][11] Currently, the main commercial WLEDs are to combine a 460 nm emitting LED chip and a yellow-emitting YAG:Ce 3+ phosphor. [12][13][14][15][16] However, this combination suffers from the disadvantages of high correlated color temperature (CCT) and low color rendering index (Ra) because of insufficient red light components. [17][18][19][20] Another alternative means for obtaining white light is by combining near ultraviolet LED (n-UV-LED) chips with tricolor phosphors. [21][22][23][24] Either way, the red light component is essential for obtaining high-quality white light. Therefore, many researchers are committed to developing red phosphors with excellent properties. There are some reports on red emitters, such as Sr [LiAl 3 N 4

Ni2+-activated MgTi2O5 with broadband emission beyond 1200 nm for NIR-II light source applications

“…In previous reports, research on NIR phosphors for NIR-LEDs is mainly focused on trivalent rare earth (RE) ions (Tm 3+ , Pr 3+ , and Nd 3+ ); 10–13 however, RE-activated phosphors have certain drawbacks such as low efficiency and a narrow excitation/emission bandwidth, which hinder their application for NIR-II pc-LEDs. 14,15 Cr 3+ and Eu 2+ doped phosphors are another research hotspot in the field of inorganic NIR luminescent materials, 3,16–18 such as X 3 Sc 2 Ga 3 O 12 :Cr (X = Lu, Y, Gd, and La) (from 600 to 1000 nm), 19 CaAlSiN 3 :Eu 2+ (from 500 to 800 nm), 20 and K 3 ScSi 2 O 7 :Eu 2+ (from 600 to 1100 nm).…”

Broad luminescence tuning in Mn2+-doped Rb2Zn3(P2O7)2via doping level control based on multiple synergies

“…The peak at 590 nm should be ascribed to the Mn 2+ –Mn 2+ dimers (peak3, abbreviated as P3), which is reported in the SrGa 2 Si 2 O 8 :Mn 2+ systems by Wang et al 15 In general, the Mn 2+ –Mn 2+ dimers are formed at a high doping concentration due to the critical distance of about 5 Å. 18 For example, through heavy doping of Mn 2+ into the MgAl 2 O 4 host, the distance between the super-exchange coupled IV Mn 2+ – VI Mn 2+ pair is 3.14 Å, leading to broad-band NIR emission. 19 However, in the RZPO: x Mn 2+ system, the Mn 2+ –Mn 2+ dimers are formed at a low doping concentration ( x = 0.01), and this is proved by the electron paramagnetic resonance (EPR) analysis.…”

Enhanced and Broadened NIR Emission of CaZnGe2O6:Cr3+ by Yb3+ Codoping for NIR Applications

“…Therefore, it is urgent to improve their emission efficiency and broaden their emission band for deep-red and NIR phosphors. Many phosphors have been reported to realize deep-red and NIR emission including rare earth (RE) (Pr 3+ , Nd 3+ , Tm 3+ , Yb 3+ , Eu 2+ ), transition metal (Ni 2+ , Mn 2+ , Mn 4+ , Fe 3+ , Cr 3+ ), and major group element (Bi + , Bi 0 ) ion activated phosphors. − Compared with other activated phosphors, though Cr 3+ activated phosphors have broader emission bands, their emission intensity is not enough and their emission spectra are still not as broad as expected, so they are still difficult to apply in portable NIR spectroscopy and night vision lighting. Because of the outermost 3d 3 electronic configuration of Cr 3+ , the octahedrally coordinated Cr 3+ activated phosphors often have a linear emission peak around 700 nm in a strong crystal field, which can be ascribed to the 2 E g → 4 A 2g transition, or broadband emission in the NIR range at a weak crystal field, which originates from the 4 T 2g → 4 A 2g transition.…”