Spatially confined luminescence process in tip-modified heterogeneous-structured microrods for high-level anti-counterfeiting

Abstract

Recent years have witnessed the progress of lanthanide-doped materials from fundamental material synthesis to targeted practical applications such as optical applications in photodetection, anti-counterfeiting, volumetric display, optical communication, as well as biological imaging. The unique compositions and structures of well-designed lanthanide ion-doped materials could expand and strengthen their application performances. Herein, we report dual-mode luminescent crystalline microrods that spatially confine upconversion and downconversion photophysical process within defined regions using the specially designed heterogeneous structure. Through an epitaxial growth procedure, downconversion tips have been conjugated with the parent upconversion microrods in oriented directions. This spatially confined structure can effectively depress the deleterious energy depletion in lanthanide ions homogeneously doped materials, and as a result, the red, green, and blue upconversion intensities have been enhanced by 334, 225, and 22 times, respectively. Moreover, the induced tips hardly disturb the upconversion process of the microrod seeds. Upon 980 nm laser or ultraviolet lamp excitation, tunable emission colors were realized in the single tip-modified microrod, indicating potential applications of these microrods for high-level dual-mode anti-counterfeiting.

Morphology Manipulation and Upconversion Luminescence Enhancement of β-NaLuF4: Er3+ Hexagonal Microtubes via Sr2+ Doping

“…In the past few decades, countless scientific researches about trivalent lanthanide ion-(Ln 3+ -) doped UC materials have aroused widespread attention owing to their applications in many promising fields, such as photovoltaic cells, biological detection, temperature sensing, DNA detection, and photodynamic therapy (PDT) [2][3][4][5][6][7][8][9][10]. As a typical upconversion matrix material, NaYF 4 crystal has attracted much attention due to its low phonon energy (<350 cm -1 ), long luminescence lifetime, and high thermal stability and has been widely studied [6,[10][11][12][13][14]. The crystal structure of NaLuF 4 is similar to NaYF 4 , with a smaller ion radius (Y 3+ = 0:89 Å, Lu 3+ = 0:86 Å), and it is also considered an ideal substitute for the ideal UC matrix [15][16][17][18][19][20].…”

Physical Manipulation of Lanthanide‐Activated Photoluminescence

“…In contrast to other types of luminescent materials such as organic fluorescent materials and semiconducting quantum dots, lanthanide-activated luminescence shows distinctive advantages, such as sharp multi-peak emission, large Stokes/anti-Stokes shift, long lifetime, and excellent photostability. [3] The unique luminescent characteristics and energy transfer variety impart lanthanide materials great potentials in a wide range of fields, including but not limited to display and lighting, [4,5] laser, [6] information security, [7][8][9][10] sensing and detection, [11][12][13][14][15] biological imaging and therapy, [16][17][18] photocatalysis, and optoelectronic device. [2] Downshifting and quantum cutting belong to the conventional Stokes process where the emission energy is lower than the excitation energy.…”

Simultaneous Dual-mode Emission and Tunable Multicolor in the Time Domain from Lanthanide-doped Core-shell Microcrystals

“…Lanthanide (Ln 3+ )-doped luminescent materials with various compositions and properties have been well studied for the last few decades. Compared with traditional luminescent materials, such as quantum dots (QDs) and organic dyes, the lanthanide-doped nano- and micro-crystals show more superior optical features including narrow bands widths, stable energy levels, low toxicity and long lifetime [1,2]. In addition, these materials have attracted a great deal of attention owing to their magnetic and thermal properties.…”

“…In addition, these materials have attracted a great deal of attention owing to their magnetic and thermal properties. These properties lead to widespread applications in various areas, such as volumetric display [3,4], solar cell [5], optical data storage [3,6,7], photothermal therapy [8,9], temperature sensing [10], laser [11,12], bioimaging [13,14] and anti-counterfeiting [2,15,16]. Ln 3+ -doped materials with tunable emission colors as security inks have been one of most commonly utilized methods for high-level anti-fake due to its difficult duplication and tunable luminescence properties [15,17,18].…”