Effectively Leveraging Solar Energy through Persistent Dual Red Phosphorescence: Preparation, Characterization, and Density Functional Theory Study of Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺

Abstract

To effectively leverage and convert cheap, abundant, and environmentally friendly solar energy is still an unaccomplished endeavor. In this work, we prepare and characterize the long-lasting red-light-emitting, singlephase Ca 2 Zn 4 Ti 16 O 38 phosphor by the sol-gel method with nonstoichiometry or addition of H 3 BO 3 as flux. Excitation and emission mechanisms are proposed and supported by the computational results from density functional theory. Phase identification of powders was performed by X-ray powder diffraction analysis, confirming the existence of single-phase Ca 2 Zn 4 Ti 16 O 38 crystals in samples of every series. Unit cell parameters of the crystal were subsequently determined, together with its excitation spectra in the blue-green region with the maximum peak at 474 nm monitored by 644 nm light. The corresponding emission spectra showed a wide emission range with two narrow bands at 614 nm ( 1 D 2 f 3 H 4 ) and 644 nm ( 3 P 0 f 3 F 2 ) after the addition of H 3 BO 3 . If excited at 474 nm, the phosphor displays a superlong afterglow with the emission peak at 614 nm, enabling it to be a novel persistent red long phosphor for visible-light conversion. Luminescent properties of the phosphor were thoroughly examined. The mechanism of the dual persistence phosphorescence originated at 614 and 644 nm wavelengths induced by two separate kinds of doping defects was proposed. Density functional theory calculations under the periodic boundary condition provide insights about their excitation, emission, and long-lasting phosphorescence mechanisms.

Visible‐Light‐Excited Ultralong‐Lifetime Room Temperature Phosphorescence Based on Nitrogen‐Doped Carbon Dots for Double Anticounterfeiting

“…Contrary to ultraviolet light, visible light is safer to use and can penetrate deeper into biological analysis and imaging; hence easily used in practical applications. Besides, visible light is more superior than ultraviolet light and has received widespread applications 7. Thus, enormous efforts have been devoted to discovering novel RTP materials that can be excited by visible light.…”

Enhanced photoluminescence of the Ca0.8Zn0.2TiO3:0.05% Pr3+ phosphor by optimized hydrothermal conditions

“…However, there is controversy on how to attribute the other two bands . A previously published paper has detailed discussion on the attribution of bands A, B and C, which accords with Boutinaud's conclusion . The diffuse reflection spectrum (black solid line) of sample 32EGE‐235(2)‐6.8 is shown in Figure (a).…”

“…Under monitoring at 612 nm, each excitation spectrum mainly consisted of two strong broad bands (A and B) and a weaker broad band that ranged from 450 to 500 nm (labeled as C). There have been many studies on the photoluminescence of Ca 2 Zn 4 Ti 16 O 38 :Pr 3+, CaTiO 3 :Pr 3+, and Ca 0.8 Zn 0.2 TiO 3 :Pr 3+. For the three excitation bands A, B and C of the CaTiO 3 :Pr 3+ phosphors, it is generally accepted that band C results from the 4 f → 4 f ( 3 H 4 → 3 P 0, 1, 2 + 1 I 6 ) transition of Pr 3+ .…”

Phosphorescence behavior and photoluminescence mechanism of Dy 3+ sensitized β-Zn 3 (PO 4 ) 2 : Mn 2+ phosphor

“…Over the past decades, rare-earth (especially Eu) ions activated LPP materials have been widely studied and applied in safety indication, graphic arts, road signs, interior decoration, radiation detection, structural damage sensors and optical storage media [3][4][5][6]. Up to now, more and more realms such as solar energy utilization and in vivo bio-imaging have used long-lasting phosphors to solve correlative questions [7,8]. LPP can exhibit variety of colors in the darkness, most especially blue (CaAl 2 O 4 : Eu 2+ , Nd 3+ ) and green (SrAl 2 O 4 : Eu 2+ , Dy 3+ ) [9][10][11].…”