Explaining the influence of dopant concentration and excitation power density on the luminescence and brightness of β-NaYF4:Yb3+,Er3+ nanoparticles: Measurements and simulations

Primary Luminescent Nanothermometers for Temperature Measurements Reliability Assessment

“…Although brightness, as defined in Equation (), is a commonly reported figure for downshifting materials, [ 58–62 ] it is not common for upconverting materials. To enable a comparison with the literature, an alternative definition will be considered [ 46,63 ] where σ UCNP is the effective absorption cross‐section, determined using Equation S17, Supporting Information. According to Equation (), B(980) = (1.5 ± 0.3) × 10 −19 and B (808) = (1.1 ± 0.2) × 10 −20 cm 2 .…”

Near infrared bioimaging and biosensing with semiconductor and rare-earth nanoparticles: recent developments in multifunctional nanomaterials

“…85,86 Generally, RENPs are the result of embedding Ln 3+ within the crystalline structure of a proper dielectric host material which has three main fundamental roles: i) crystal structure asymmetry and crystal field can be used to increase the probability of the 4f-4f transitions; ii) low cutoff phonon energies reduce non-radiative quenching of the excited states, and iii) host matrix serves as a platform where different sensitizers and activators can be combined to achieve specific luminescent features. [87][88][89] Page 22 of 48 Nanoscale Advances RENPs can be produced by multiple approaches, which can be generally split into syntheses performed in organic solvents, or in aqueous media. Thermal decomposition is a common method to produce RENPs due to its relatively simple procedure, consisting of the decomposition of organo-metallic Ln 3+ precursors at high temperatures.…”

The effects of dopant concentration and excitation intensity on the upconversion and downconversion emission processes of β-NaYF4:Yb3+,Er3+ nanoparticles

“…In general, an optimal Yb 3+ concentration between 17%-20% is assumed while the Er 3+ concentration is kept relatively low (around 2%-4%) to guarantee the distance between dopants and thus to minimize the energy loss resulting from cross-relaxation. [23][24][25][26] For example, Wang et al 23 found that green-fluorescence lifetime of NaYF 4 :Yb/Er nanoparticles increases when diminishing Er 3+ concentration from 32% down to 0.5% while keeping constant Yb 3+ concentration at 20%. Cao et al 25 studied powders samples of NaYF 4 doped with 2% of Er 3+ and a wide range of Yb 3+ codoping concentrations finding that the strongest visible emission occurs at 20% of Yb 3+ , since a greater increase in Yb 3+ concentration induces a transition from hexagonal to cubic phase, thus decreasing the fluorescence emission.…”