Multimode Highly Tunable Photoluminescence of Eu³⁺ Ions Induced by Surface Photovoltage of Bi₉V₂O₁₈Cl Perovskite Oxychloride Nanosheets and Application for Advanced Anticounterfeiting Agents

Abstract

As most trivalent lanthanides are hypersensitive, surface photovoltage (SPV) that is associated with charge separation in a space charge region of a semiconductor might become a new method for harvesting the photoluminescence of rare earth (RE) ion-doped optical materials. To confirm this new technology, the highly tunable photoluminescence of Eu3+-doped Bi9V2O18Cl layered perovskite and its anticounterfeiting application are reported. It shows that under the spontaneous inter electric field of Bi9V2O18Cl, the SPV signals with significant wavelength and concentration dependence are photogenerated along the sheet crystals. Consequently, changing the excitation wavelength from visible to ultraviolet light, the dominant emission of Eu3+ ions vary from 5D0 → 7F2 to 5D0 → 7F4 transition by the increasing SPV, accompanying with a greatly extended radiative rate; meanwhile, the SPV of the layered host enables an emission modification of Eu3+ ions similarly via changing its doping level, offering a different and multimode luminescence anticounterfeiting method. Besides enriching the understanding of the RE-doped optical materials, the results of this work can offer a novel luminescent anticounterfeiting pigment that is designable through control of the excitation wavelength and the tagged composition is expected to provide high-level security.

Unveiling the Local Structure and Luminescence Mechanism of Er3+-Doped LiYF4: A Promising Near-Infrared Laser Crystal

“…The typical luminescence of rare-earth nanoparticles has attracted extensive interest in recent years due to their many advantages, such as narrow band emission, high quantum efficiency, spectral sharpness, and long emission lifetimes. − Owing to this fantastic advantage related to f–f internal transitions, these optical properties have potential applications in lasing, bioimaging, quantum technologies, security technologies, highly reliable all-fiber temperature sensors, etc. − Among rare-earth ions, Er 3+ ions have received the most attention for long-lived states in the yttrium lithium fluoride crystal (a low phonon lattice), for example, the 4 I 13/2 multiplet has a radiative lifetime of up to 10 ms . In this case, a great many of radiative transitions of Er 3+ ions in the fluoride scheelite crystal can be easily obtained, which could be used in lasing action.…”

Locking Energy Transfer of Rare Earth Ions via an “Electron Jam” Caused by Vertical Photocarrier Separation of a Layered Semiconductor

“…To form an energetically stable state, internal screening in the format of a space-charge region will form close to the surface. The surfaces where the positive potential and negative potential are produced by the polarization are termed as C + face and C – face, which facilitates the separation of electron–hole pairs, as schematically shown in Figure (f). , Owing to the roughness and irregular geometric shapes of the prepared sheet crystals, we used piezoresponse force microscopy (PFM) to detect the polarization property of the Bi 3 O 4 Cl layered crystals, which is shown in Supporting Information (Figure S4).…”

Current Developments in Emerging Lanthanide‐Doped Persistent Luminescent Scintillators and Their Applications

“…Therefore, it is urgent to develop safe and reliable anti‐counterfeiting technologies and the necessary information coding means. Due to the unique optical properties of lanthanide‐doped PersLSs, they have been widely used in the field of optical security, such as information encryption, anti‐counterfeiting, etc [182,183] . In addition, PersL can also provide additional time‐dimensional luminescence for information alteration and encryption, further enhancing the anti‐counterfeiting properties [184,185] .…”

“…Due to the unique optical properties of lanthanide-doped PersLSs, they have been widely used in the field of optical security, such as information encryption, anti-counterfeiting, etc. [182,183] In addition, PersL can also provide additional time-dimensional luminescence for information alteration and encryption, further enhancing the anti-counterfeiting properties. [184,185] In turn, sophisticated and highly secure anti-counterfeiting strategies with multiple luminescent modes further increase the security level of the evolving information storage and information encryption.…”