Stokes Luminescence Research Articles

(Invited) Manipulating Light Emission from Rare Earth Doped Nanoparticles for Applications in Theranostics

Luminescent nanomaterials that can be excited, as well as emit, in the near-infrared (NIR) have been investigated for use in a plethora of applications including nanomedicine, nanoelectronics, biosensing, bioimaging, photovoltaics, photocatalysis, etc. The use of NIR light for excitation mitigates some of the drawbacks associated with high-energy (UV or blue) excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is of course, that of penetration. As such, NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows (BW-I: 700-950, BW-II: 1000-1350, BW-III: 1550-1870 nm) where tissues are optically transparent. At the forefront of NIR excited nanomaterials are rare earth doped nanoparticles, which due to their 4f electronic energy states can undergo conventional (Stokes) luminescence and emit in the three NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton process (known as upconversion) where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions. Perhaps the biggest impact of such materials would be in the field of disease diagnostics and therapeutics, now commonly referred to as theranostics. Due to the versatility of their optical properties, it now becomes possible to generate high-energy light (UV or blue) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we present the synthesis of various NIR excited (and emitting) rare earth doped core/shell (and multishell) nanoparticles and demonstrate how their luminescence properties can be exploited for potential use in diverse biomedical applications.

Study on the mechanism of high energy transfer efficiency of blue light excited Cr3+, Nd3+ co-doped near infrared phosphors.

Although Cr3+ as activator for Near infrared (NIR) phosphors has been widely studied, the peaks of Cr3+ emission spectra in most hosts are less than 1000 nm. Nd3+ as an activator in many hosts has a wide distribution of absorption peaks in the Ultraviolet-visible-Near infrared (UV-vis-NIR) band, especially in the 650-900 nm band for effective NIR to NIR Stokes luminescence (4F3/2→4I9/2, 4F3/2→4I11/2 transitions). Therefore, Cr3+, Nd3+ co-doping to achieve the emission in the NIR II region (1000-1700nm) is very meaningful. Here, we report La2CaZrO6(LCZO): Cr3+, Nd3+ NIR phosphors with emission spectra covering an ultra-wide range of 700-1400 nm and reveal their luminescence mechanism. The energy transfer efficiency of Cr3+ for Nd3+ can be as high as 88.4% under 471 nm blue light excitation. In the same case, the integrated intensity of the emission spectra of Cr3+, Nd3+ co-doped can reach 847% of that of Nd3+ alone and 204% of that of Cr3+ alone. Finally, the combination of commercial blue light chips and Cr3+, Nd3+ co-doped NIR phosphors shows great potential for applications in face recognition, night lighting, and angiography.

Stokes and Anti-Stokes Luminescent Rare-Earth-Doped Tantalum Oxide Nanoparticles.

Doping of nano- and microparticles of oxides with rare earth elements (REEs) is used to fine-tune their structural, optical, and electrochemical properties. On the way to establish the structure-property relationship, we dope tantalum oxide (Ta2O5) particles with REEs to study their effect on the oxide structure and luminescence. Ta2O5 is highly perspective in medicine, catalysis, and optics, but its crystal structure is insufficiently studied. Two synthesis approaches (sol-gel and solvothermal) were used to obtain powders with different textures. Experimental and theoretical studies of amorphous and crystallized tantalum oxide NPs by means of X-ray powder diffraction, Rietveld analysis, EXAFS/XANES spectroscopy, and density functional theory calculations were performed. All samples (doped and undoped) crystallized in orthorhombic phase with no admixtures. It was demonstrated that Ta2O5 is a promising wide-spectrum luminescent material: by combining REEs, both Stokes and anti-Stokes luminescence in the visible region were obtained. By means of optical absorption spectroscopy, it was shown that the prepared samples could be classified as wide band gap semiconductors.

Наночастицы NaLuF-=SUB=-4-=/SUB=-: Yb-=SUP=-3+-=/SUP=-, Er-=SUP=-3+-=/SUP=-, Ce-=SUP=-3+-=/SUP=- для создания компактных волноводных усилителей и визуализации в ближнем ИК диапазоне спектра

Fluoride nanocrystals co-doped with lanthanide ions are well known due to the possibility of conversion near-infrared (NIR) radiation into photoluminescence with large anti-Stokes shift. Owing to upconversion effect, such nanomaterials have shown great potential in photonics and biomedicine. However, fluoride nanoparticles can be reconfigured to photoluminescence with a Stokes shift into the near-infrared region of the spectrum. In this work, we focused on the properties of NaRF4: Yb3+, Er3+, Ce3+ (R = Y, Lu) nanoparticles exhibiting intense stokes luminescence in the vicinity of 1530 nm at 975 nm excitation. Photoluminescence quantum efficiency of synthesized nanoparticles was evaluated as 28% at 0.6 W/cm2 excitation intensity. Based on the photoluminescent properties of nanoparticles we designed compact waveguide amplifier for C-band telecommunication and developed time gated imaging system for NIR-to-NIR biovisualization.

(Invited) Rare Earth Doped Nanoparticles

Luminescent nanomaterials that can be excited, as well as emit, in the near-infrared (NIR) have been investigated for use in a plethora of applications including nanomedicine, nanoelectronics, biosensing, bioimaging, photovoltaics, photocatalysis, etc. The use of NIR light for excitation mitigates some of the drawbacks associated with high-energy (UV or blue) excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is of course, that of penetration. As such, NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows (BW-I: 700-950, BW-II: 1000-1350, BW-III: 1550-1870 nm) where tissues are optically transparent. At the forefront of NIR excited nanomaterials are rare earth doped nanoparticles, which due to their 4f electronic energy states can undergo conventional (Stokes) luminescence and emit in the three NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton process (known as upconversion) where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions. Perhaps the biggest impact of such materials would be in the field of disease diagnostics and therapeutics, now commonly referred to as theranostics. Due to the versatility of their optical properties, it now becomes possible to generate high-energy light (UV or blue) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we present the synthesis of various NIR excited (and emitting) rare earth doped core/shell (and multishell) nanoparticles and demonstrate how their luminescence properties can be exploited for potential use in diverse biomedical applications.

Synthesis, structure, Stokes and anti-Stokes visible luminescence of Tm3+–Yb3+ co-doped Lu3Sc2Ga3O12 nanorods

Synthesis, structure, Stokes and anti-Stokes visible luminescence of Tm3+–Yb3+ co-doped Lu3Sc2Ga3O12 nanorods

(Invited) Multi-Architectured Lanthanide Doped Nanoparticles for Theranostics

Light triggered theranostic (therapy and diagnostic) nanoplatforms have gained a considerable attention in recent years. In theranostics, light as an external trigger stands out due to its non-invasiveness, high local precision and temporal resolution. Many such nanoplatforms employ high-energy (visible or UV) light to initiate the individual therapeutic and diagnostic modalities. However, light at these wavelengths suffers from inherent drawbacks such as having little to no penetration in living tissue, inducing autofluorescence from inherent fluorophores or chromophores in tissues and causing photodamage. The use of near-infrared (NIR) light for excitation mitigates such drawbacks associated with high-energy excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is that of penetration and NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows where tissues are optically transparent. At the forefront of NIR excited nanomaterials are lanthanide doped nanoparticles, which can undergo conventional (Stokes) luminescence and emit in the NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton excitation process where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions (known as upconversion). Thus, it now becomes possible to generate upconverted high-energy light (UV or visible) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we demonstrate how the luminescence properties (upconversion and NIR) of various lanthanide doped core/shell (and multishell) nanoparticles can be exploited for potential use in theranostics.

Time–thermo-dynamics of anti-Stokes and Stokes scattering and luminescence in 1-nm silicon nanoparticles: Toward an optical nanorefrigerator

The thermodynamics of nanosystems is interesting, as they constitute the transition between the atomistic and solid states. This is empowered by the development of tools to manipulate individual atoms and perform atomistic simulations and fundamental thermos-science, such as microscopic time-symmetry and macroscopic time-asymmetry, the origin of time’s arrow, and photo-cryo-refrigeration. We examine here the photo-thermo and time dynamics in 1-nm silicon nanoparticles with tetrahedral-molecular core–shell structure prepared ex situ and suspended in solvents or re-constituted in films. We examined the temperature dependence of the quantum efficiency and time-dynamics of the Stokes luminescence and its energy dependence across the band. With temperature, we get flat lifetimes but with delay in the onset in agreement with a model calculation of above barrier emission. Our atomistic time-dependent density functional theory shows that Stokes heating takes place in the molecular-like shell where the lifetime is in the nanosecond regime, whereas anti-Stokes cooling takes place in the tetrahedral core where the lifetime is in the ms regime. Unlike doped glasses, we observed a 2-order of magnitude increase in the quantum efficiency of the Stokes luminescence at 10° K. The increase in the quantum efficiency at low temperature, the high quantum efficiency of stimulated anti-Stokes scattering and its anti-correlation with the luminescence, and the visible transparency/blindness due to quantum confinement are requirements for solid state photo-cooling, which may afford an all-silicon photo-cryo-refrigeration, with potential full integration into the CMOS silicon industry.

(Invited) Lanthanide Doped Nanoparticles and Their Applications

Since approximately 2000, lanthanide doped nanoparticles have received significant attention due to their interesting luminescent properties. At the core of this interest is their ability to convert near-infrared excitation light (typically 980 or 800 nm) to higher energies spanning the ultraviolet, visible and near-infrared regions of the spectrum through a multiphoton process known as upconversion. Upconversion differs from conventional multiphoton excitation in other materials where no real intermediate states are present necessitating the use of ultrafast lasers (in the femtosecond regime) for simultaneous excitation to the upper emitting state. The lanthanide ions possess a multitude of 4f electronic states that have long lifetimes (micro- to millisecond) thus act as population reservoirs in the upconversion process. Hence, upconversion occurs through real, long-lived intermediate states through a sequential photon absorption process. This eliminates the need for ultrafast excitation and as a result, upconversion can be observed using inexpensive, continuous wave diode lasers. Upconversion luminescence can be exploited for a number of applications in nanomedicine, theranostics, photovoltaics, photocatalysis, as well as many others.While their upconversion luminescence has been studied in great detail, lanthanide doped nanoparticles can also emit in the near-infrared through a direct Stokes (down-shifted) luminescence process. Of particular importance is that these near-infrared emissions lie within the biological windows where biological tissues are optically transparent. For obvious reasons, a great deal of the work on the nanomedicine and theranostics applications of lanthanide doped nanoparticles has shifted to their near-infrared luminescence properties.In this presentation, we will demonstrate the synthesis of these nanoparticles, establish how changing their nanoscale architecture can affect their luminescence properties (both upconversion and near-infrared), and discuss their potential applications, particularly in nanomedicine.

Discovery of near-infrared persistent phosphorescence and Stokes luminescence in Cr3+ and Nd3+ doped GdY2Al3Ga2O12 dual mode phosphors

The near-infrared (NIR) luminescence materials have attracted great attention on account of their potential applications in optical imaging field. In this paper, a series of Cr3+ and Nd3+ doped GdY2Al3Ga2O12 phosphors with luminescence in the biological windows were synthesized using a solid-state reaction method. The crystal field parameters, concentration dependent photoluminescence and persistent luminescence properties of Cr3+ were discussed in detail. Nd3+ ions exhibit perfect NIR to NIR Stokes luminescence in the host. The influence of Nd3+ doping concentration was studied by emission spectra and decay curves. Taking the advantages of both Cr3+ and Nd3+, dual mode phosphors with NIR persistent luminescence and NIR to NIR Stokes luminescence were designed and achieved. Based on the energy transfer process, persistent luminescence and thermo-luminescence curves, the luminescence mechanism was proposed.

Tunable broadband upconversion luminescence from Yb3+/Mn2+ co-doped dual-phase glass ceramics

In comparison to narrow-band upconversion (UC) luminescence from lanthanide-doped systems, broadband UC emission enables a broad and tailorable emissive color, which is desirable for tunable lasers and multicolor display applications. Herein, dual continuous broadband UC emission covering the visible spectral region at 480–720 nm has been achieved for the first time in Yb3+/Mn2+ co-doped glass ceramics (GCs) functionalized with the precipitation of dual-phase γ-Ga2O3/β-YF3 nanocrystals. A tunable UC emissive color from yellowish to orange could be obtained under 980 nm excitation by varying the Mn2+ doping content and heat treatment temperature of GCs. We ascribe this phenomenon to the typical transition of exchange-coupled Yb3+-Mn2+ dimers in tetrahedral and octahedral ligand environments. The Stokes and power-dependent UC luminescence properties, fluorescence lifetimes, site occupation and the involved UC mechanism are discussed in detail. This research contributes to a better understanding of the UC process between Yb3+ and Mn2+ in transparent hosts and provides a novel perspective for designing broadband-emitting UC materials.

Luminescence of Pr-Doped CsxRb1– xPb2Br5 Crystals

Excitation and spontaneous photoluminescence spectra of CsxRb1– xPb2Br5:Pr (0.8 at % Pr) crystals have been studied at different cesium concentrations (x = 0.1, 0.2, and 0.3) and temperatures. The Stokes luminescence intensity in the praseodymium-doped crystals in the red spectral region has been shown to increase with increasing cesium concentration. We have determined the activation energy for the thermal quenching of visible emission bands of the crystals under excitation with blue light at 450 nm and identified the corresponding electron transitions in emission centers (praseodymium ions) for different luminescence bands.

(Invited) Towards New Near-Infrared Triggered Theranostic Nanoplatforms

Light triggered theranostic (therapy and diagnostic) platforms have gained a considerable attention in recent years. In theranostics, light as an external trigger stands out due to its non-invasiveness, high local precision and temporal resolution. Many such theranostic nanoplatforms employ high-energy (visible or UV) light to initiate the individual therapeutic and diagnostic modalities. However, light at these wavelengths suffers from inherent drawbacks such as having little to no penetration in living tissue, induces autofluorescence from inherent fluorophores or chromophores in tissues and can cause photodamage. The use of NIR light for excitation mitigates such drawbacks associated with high-energy excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is of course, that of penetration. As such, NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows (BW-I: 700-950, BW-II: 1000-1350, BW-III: 1550-1870 nm) where tissues are optically transparent. At the forefront of NIR excited nanomaterials are rare earth doped nanoparticles, which due to their 4f electronic energy states can undergo conventional (Stokes) luminescence and emit in the three NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton excitation process where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions (commonly known as upconversion). Due to the versatility of their optical properties, it now becomes possible to generate upconverted high-energy light (UV or blue) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we present the synthesis of various NIR excited (and emitting) rare earth doped core/shell (and multishell) nanoparticles and demonstrate how their luminescence properties can be exploited for potential use in theranostics.

Erbium luminescence in (Y, Er, Yb)3Al5O12 powders

In this work, the Stokes and anti-Stokes luminescence (upconversion) of erbium in powders of yttrium-aluminum garnet with various concentrations of erbium, as well as co-doped with erbium and ytterbium, synthesized by the sol-gel method using multistage thermal processing, was investigated. It was established that the phase composition of the resulting powders corresponds to the crystal structure of garnet. For all powders, high-intensity Stokes luminescence with a maximum at 1.53 μm was observed due to the I13/24→I15/24 electronic transition, and anti-Stokes luminescence was observed with the most intense band in the region of 0.65–0.69 μm, associated with the F9/24→I15/24 transition of Er3+ ions. The highest intensity of the Stokes luminescence is observed for the maximum substitution of yttrium by erbium considered here, which corresponds to the Yb1.5Er1.5Al5O12 stoichiometry. The highest intensity of the anti-Stokes luminescence is for the lowest erbium concentration and for codoping with ytterbium with Y2.71Er0.29Al5O12 and Y2Er0.5Yb0.5Al5O12 stoichiometries, respectively.

Anti-stokes luminescence of CsCdBr3:Tm crystals

Transmission and spontaneous photoluminescence excitation spectra of CsCdBr3:Tm (1 and 2.5 at % Tm) crystals have been studied under different optical pumping conditions. The results demonstrate that the anti-Stokes luminescence intensity in the thulium-doped crystals is higher at the higher doping level. We have determined the resonance wavelengths of IR photons for two-photon excitation of visible luminescence in CsCdBr3:Tm and identified the corresponding electronic transitions in thulium-related emission centers for Stokes and anti-Stokes luminescence.

Enhanced VIS and NIR emissions of Pr3+ ions in TZYN glasses containing silver ions and nanoparticles

TeO2-ZnO-YF3-NaF glasses doped with Pr2O3 and containing AgNO3 were prepared for the first time by single step melt quenching technique. Ag nanoparticles were grown by controlled heat treatment of the glasses during different periods of times (up to 10 h) at 300 °C, which is below the glass transition temperature. TEM images show the presence of Ag NPs with average diameter 10–46 nm and, in agreement, a broad absorption band, peaked around 492 nm, was observed and attributed to the surface plasmon resonance band (SPR) of the NPs in Pr3+ free glasses. UV–Vis absorption, and visible and near-infrared steady state and time-dependent fluorescence techniques were used to characterize the effect of the NPs on the emission properties of Pr3+. The enhancement of Pr3+ Stokes luminescence with the increase in NPs concentration was observed for samples excited in resonance (480 nm) and off-resonance (440 and 470 nm) with the SPR band. An increase of the excited state lifetime value for Pr3+:3P0 level was also observed in the presence of other Ag species (dimmers, trimmers, molecule-like and non plasmonic Ag particles) and NPs. Thus, the results show that besides the possible local field effect of the NPs, the enhancement of luminescence intensity is also likely to be due to energy transfer from the Ag species to Pr3+ ions. These new glasses show interesting properties that could become useful for photonic device applications.

Upconversion Luminescent Chemodosimeter Based on NIR Organic Dye for Monitoring Methylmercury In Vivo

While most luminescent organic dyes display intense Stokes fluorescence, some of them exhibit unique single‐photon frequency upconversion luminescence (FUCL). Compared to conventional anti‐Stokes luminescence of lanthanides and two‐photon excitation, FUCL materials display adjustable spectrum area and require a much lower excitation power. Although this is very beneficial for biological applications in the perspective of reducing photodamage to biological samples and photobleaching of the dyes, the utilization of FUCL for biosensing and bioimaging in vivo has not been reported. In this study, we developed a near‐infrared (NIR) rhodamine derivative (FUC‐1) as a chemodosimeter, which displays weak luminescence but undergoes thiolactone ring‐open process leading to luminescence turn‐on in response to mercury(II) cation or methylmercury with good selectivity and high sensitivity in aqueous solution. Interestingly, FUC‐1 displays particular FUCL, excitation at 808 nm leads to luminescence at 745 nm. Compared to Stokes luminescence resulted from excitation at 630 nm, the use of FUCL lowers the detection limit of Hg2+ to be 0.207 nM. FUC‐1 has been used for FUCL bioimaging of methylmercury in live cells and mice. To the best of our knowledge, this is the first example of FUCL biosensing and bioimaging in vivo using visible and NIR fluorescence of small‐molecular dyes.

Stokes and anti-Stokes luminescence in Tm(3+)/Yb(3+)-doped Lu3Ga5O12 nano-garnets: a study of multipolar interactions and energy transfer dynamics.

Nanocrystalline Lu3Ga5O12 garnets doped with Tm(3+)/Yb(3+) ions have been synthesized by a low cost and environmentally benign sol-gel technique and characterized for their structural, Stokes and anti-Stokes luminescence properties. The diffuse reflectance spectra of doped Lu3Ga5O12 nano-garnets have been measured to derive the partial energy level structure of Tm(3+) and Yb(3+) ions and possible energy transfer channels between them. Upon laser excitation at 473 nm, weak red and intense near-infrared Stokes emissions have been observed in the nano-garnets. The decay curves of (3)H4 and (1)G4 levels of Tm(3+) ions and the (2)F5/2 level of Yb(3+) ions have been measured upon resonant laser excitation and are found to be non-exponential in nature due to multipolar interactions. In order to know the kind of multipolar interaction among optically active ions, the decay curves are analyzed through the generalized Yokota-Tanimoto model. Moreover, under 970 nm laser excitation, intense blue anti-Stokes emission is observed by the naked eye in Tm(3+)-Yb(3+) co-doped Lu3Ga5O12 nano-garnets. The results show that as-synthesized nano-garnets may be useful in the field of phosphors and photonics.

Two blinking mechanisms in highly confined AgInS2 and AgInS2/ZnS quantum dots evaluated by single particle spectroscopy.

Ternary AgInS2 quantum dots (QDs) have been found as promising cadmium-free, red-shifted, and tunable luminescent bio-probes with efficient Stokes and anti-Stokes excitations and luminescence lifetimes (ca. 100 ns) convenient for time resolved techniques like fluorescence life-time imaging. Although the spectral properties of the AgInS2 QDs are encouraging, the complex recombination kinetics in the QDs being still far from understood, limits their full utility. In this paper we report on a model describing the recombination pathways responsible for large deviations from the first-order decay law observed commonly in the ternary chalcogenides. The presented results were evaluated by means of individual AgInS2 QD spectroscopy aided by first principles calculations including the electronic structure and structural reconstruction of the QDs. Special attention was devoted to study the impact of the surface charge state on the excited state relaxation and effect of its passivation by Zn(2+) ion alloying. Two different blinking mechanisms related to defect-assisted charge imbalance in the QD responsible for fast non-radiative relaxation of the excited states as well as surface recharging of the QD were found as the major causes of deviations from the first-order decay law. Careful optimization of the AgInS2 QDs would help to fabricate new red-shifted and tunable fluorescent bio-probes characterized by low-toxicity, high quantum yield, long luminescence lifetime, and time stability, leading to many novel in vitro and in vivo applications based on fluorescence lifetime imaging (FLIM) and time-gated detection.

Unusual Effect of Cerium Codoping on Stokes and Anti-Stokes Luminescence of BiOCl:Er 3+ Crystal

Effect of cerium codoping on Stokes or anti-Stokes luminescence of BiOCl:Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> crystals, which were controlled by a special photon avalanche (PA) mechanism under 980-nm excitation, was investigated. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis indicate that Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions were successfully doped into BiOCl lattices. However, in PA photoluminescence behaviors, the doped Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions did not present efficient resonant energy transfer (ET) processes between the Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions as generally reported. As a result, the intensity of visible PA upconversion emission and 1.54 $\mu\text{m}$ downshifting near-infrared (NIR) emission of Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions shows the same concentration dependence of cerium dopants. This phenomenon can be understood by the influence of cerium dopant content on the magnitude of internal electric field in layered BiOCl crystals, which may play a more important role on the upconversion (UC) and NIR luminescence of Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> than the traditional ET between rare-earth (RE) ions. The results of our work may offer a different understanding for the method to control the emissions of RE ions.