Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-55134 Zeitschriftenartikel Würth, Christian; Grauel, Bettina; Pons, Monika; Frenzel, Florian; Rissiek, P.; Rücker, Kerstin; Haase, Markus; Resch-Genger, Ute Yb- and Er concentration dependence of the upconversion luminescence of highly doped NaYF4:Yb,Er/NaYF4:Lu core/shell nanocrystals prepared by a water-free synthesis High sensitizer and activator concentrations have been increasingly examined to improve the performance of multi-color emissive upconversion (UC) nanocrystals (UCNC) like NaYF4:Yb,Er and first strategies were reported to reduce concentration quenching in highly doped UCNC. UC luminescence (UCL) is, however, controlled not only by dopant concentration, yet by an interplay of different parameters including size, crystal and shell quality, and excitation power density (P). Thus, identifying optimum dopant concentrations requires systematic studies of UCNC designed to minimize additional quenching pathways and quantitative spectroscopy. Here, we quantify the dopant concentration dependence of the UCL quantum yield (ΦUC) of solid NaYF4:Yb,Er/NaYF4:Lu upconversion core/shell nanocrystals of varying Yb3+ and Er3+ concentrations (Yb3+ series: 20%‒98% Yb3+; 2% Er3+; Er3+ series: 60% Yb3+; 2%‒40% Er3+). To circumvent other luminescence quenching processes, an elaborate synthesis yielding OH-free UCNC with record ΦUC of ~9% and ~25 nm core particles with a thick surface shell were used. High Yb3+ concentrations barely reduce ΦUC from ~9% (20% Yb3+) to ~7% (98% Yb3+) for an Er3+ concentration of 2%, thereby allowing to strongly increase the particle absorption cross section and UCNC brightness. Although an increased Er3+ concentration reduces ΦUC from ~7% (2% Er3+) to 1% (40%) for 60% Yb3+. Nevertheless, at very high P (> 1 MW/cm2) used for microscopic studies, highly Er3+-doped UCNC display a high brightness because of reduced saturation. These findings underline the importance of synthesis control and will pave the road to many fundamental studies of UC materials. Springer 2022 Nano Research 1 8 urn:nbn:de:kobv:b43-551346 10.1007/s12274-022-4570-5 https://creativecommons.org/licenses/by/4.0/deed.de 2022-06-29 OPUS4-53723 Vortrag Resch-Genger, Ute; Würth, Christian; Frenzel, Florian; Weigert, Florian; Andresen, Elina; Grauel, Bettina; Wegner, Karl David Semiconductor (SCNC) & Upconversion Nanocrystals (UCNC) - Optical Properties, Applications & Challenges Inorganic nanocrystals with linear and nonlinear luminescence in the ultraviolet, visible, near infrared and shortwave infrared like semiconductor quantum dots and spectrally shifting lanthanide-based nanophosphors have meanwhile found applications in the life and material sciences ranging from optical reporters for bioimaging and sensing over security barcodes to solid state lighting and photovoltaics. These nanomaterials commonly have increasingly sophisticated core/shell particle architectures with shells of different chemical composition and thickness to minimize radiationless deactivation at the particle surface that is usually the main energy loss mechanism [1]. For lanthanide-based spectral shifters, particularly for very small nanoparticles, also surface coatings are needed which protect near-surface lanthanide ions from luminescence quenching by high energy vibrators like O-H groups and prevent the disintegration of these nanoparticles under high dilution conditions. [2,3,4]. The identification of optimum particle structures requires quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield [5,6], ideally flanked by single particle studies to assess spectroscopic inhomogeneities on a particle-to-particle level for typical preparation methods [7], Moreover, in the case of upconversion nanoparticles with a multi-photonic and hence, excitation power density (P)-dependent luminescence, quantitative luminescence studies over a broad P range are required to identify particle architectures that are best suited for applications in fluorescence assays up to fluorescence microscopy. Here, we present methods to quantify the photoluminescence of these different types of emitters in the vis/NIR/SWIR and as function of Pand demonstrate the importance of such measurements for a profound mechanistic understanding of the nonradiative deactivation pathways in semiconductor and upconversion nanocrystals of different size and particle architecture in different environments. 2021 27th Annual Meeting of the Slovenian Chemical Society Portoroz-Portorose, Slovenia 21.09.2021 24.09.2021 2021-11-10 OPUS4-52784 Zeitschriftenartikel Xu, R.; Teich, W.; Frenzel, Florian; Hoffmann, Katrin; Radke, J.; Rösler, J.; Faust, K.; Blank, A.; Brandenburg, S.; Misch, M.; Vajkoczy, P.; Onken, J. S.; Resch-Genger, Ute Optical characterization of sodium fluorescein in vitro and ex vivo Objective: The utilization of fluorescein-guided biopsies and resection has been recently discussed as a suitable strategy to improve and expedite operative techniques for the resection of central nervous system (CNS) tumors. However, little is known about the optical properties of sodium fluorescein (NaFl) in human tumor tissue and their potential impact on ex vivo analyses involving fluorescence-based methods. Methods: Tumor tissue was obtained from a study cohort of an observational study on the utilization of fluorescein-guided biopsy and resection (n=5). The optical properties of fluorescein-stained tissue were compared to the optical features of the dye in vitro and in control samples consisting of tumor tissue of high-grade glioma patients (n=3) without intravenous (i.v.) application of NaFl. The dye-exposed tumor tissues were used for optical measurements to confirm the detectability of NaFl emission ex vivo. The tissue samples were fixed in 4%PFA, immersed in 30% sucrose, embedded in Tissue-Tek OCT compound, and cut to 10 mm cryosections. Spatially resolved emission spectra from tumor samples were recorded on representative slides with a Confocal Laser Scanning Microscope FV1000 (Olympus GmbH, Hamburg, Germany) upon excitation with lexc = 488 nm. Results: Optical measurements of fluorescein in 0.9% sodium chloride (NaCl) under in vitro conditions showed an absorption maximum of lmax abs = 479 nm as detected with spectrophotometer Specord 200 and an emission peak at lmax em = 538 nm recorded with the emCCD detection system of a custom-made microscope-based single particle setup using a 500 nm long-pass filter. Further measurements revealed pH- and concentration-dependent emission spectra of NaFl. Under ex vivo conditions, confocal laser scanning microscopy of fluorescein tumor samples revealed a slight bathochromic shift and a broadening of the emission band. Conclusion: Tumor uptake of NaFl leads to changes in the optical properties - a bathochromic shift and broadening of the emission band - possibly caused by the dye's high pH sensitivity and concentration-dependent reabsorption acting as an innerfilter of the dye's emission, particularly in the short wavelength region of the Emission spectrum where absorption and fluorescence overlap. Understanding the ex vivo optical properties of fluorescein is crucial for testing and validating its further applicability as an optical probe for intravital microscopy, immunofluorescence localization studies, and flow cytometry analysis. Lausanne Frontiers Media 2021 Frontiers in oncology 11 1 8 urn:nbn:de:kobv:b43-527843 10.3389/fonc.2021.654300 https://creativecommons.org/licenses/by/4.0/deed.de 2021-06-09 OPUS4-55440 Zeitschriftenartikel Zou, Q.; Marcelot, C.; Ratel-Ramond, N.; Yi, X.; Roblin, P.; Frenzel, Florian; Resch-Genger, Ute; Eftekhari, A.; Bouchet, A.; Coudret, C.; Verelst, M.; Chen, X.; Mauricot, R.; Roux, C. Heterogeneous Oxysulfide@Fluoride Core/ Shell Nanocrystals for Upconversion-Based Nanothermometry Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) often suffer from weak luminescence, especially when their sizes are ultrasmall (less than 10 nm). Enhancing the upconversion luminescence (UCL) efficiency of ultrasmall UCNPs has remained a challenge that must be undertaken if any practical applications are to be envisaged. Herein, we present a Ln3+-doped oxysulfide@fluoride core/shell heterostructure which shows efficient UCL properties under 980nm excitation and good stability in solution. Through epitaxial heterogeneous growth, a ∼4 nm optically inert β-NaYF4 shell was coated onto ∼5 nm ultrasmall Gd2O2S:20%Yb,1%Tm. These Gd2O2S:20%Yb,1%Tm@NaYF4 core/shell UCNPs exhibit a more than 800-fold increase in UCL intensity compared to the unprotected core, a 180-fold increase in luminescence decay time of the 3H4 → 3H6 Tm3+ transition from 5 to 900 μs, and an upconversion quantum yield (UCQY) of 0.76% at an excitation power density of 155 W/cm2. Likewise, Gd2O2S:20%Yb,2%Er@NaYF4 core/shell UCNPs show a nearly 5000-fold increase of their UCL intensity compared to the Gd2O2S:20%Yb,2%Er core and a maximum UCQY of 0.61%. In the Yb/Er core−shell UCNP system, the observed variation of luminescence intensity ratio seems to originate from a change in lattice strain as the temperature is elevated. For nanothermometry applications, the thermal sensitivities based on thermally coupled levels are estimated for both Yb/Tm and Yb/Er doped Gd2O2S@NaYF4 core/shell UCNPs. ACS Publications 2022 ACS Nano 1 11 10.1021/acsnano.2c02423 2022-08-04 OPUS4-37225 Vortrag Frenzel, Florian Spectroscopic study of plasmon enhanced upconversion nanoparticles The presentation gave an overview of the topic, the aims and the task allocation of the M-ERA.NET founded project named "Nanohype". In this project four research teams working hand in hand on computational modeling, synthesis and experimental validation to design novel metal-shelled Upconversion-NP combining plasmonic interactions. As Ph.D. student at the BAM I am responsible for the optical characterization (measurements of lifetimes, Quantum Yields and PL emissions ) of these promising novel systems. 2016 SpringSchool, UpCon2016 Wrocław (Breslau), Polen 25.05.2016 27.05.2016 2016-09-05 OPUS4-45573 Zeitschriftenartikel Homann, C.; Krukewitt, Lisa; Frenzel, Florian; Grauel, Bettina; Würth, Christian; Resch-Genger, Ute; Haase, M. Aufwärtskonvertierende NaYF4:Yb,Er/NaYF4-Kern/Schale-Nanokristalle mit hoher Lumineszenzquantenausbeute Eine modifizierte Syntheseroute auf der Basis wasserfreier Seltenerdacetate wurde zur Synthese aufwärtskonvertierender Kern/Schale-Nanokristalle mit mittleren Größen zwischen 15 bis 45 nm eingesetzt. Die nahezu monodispersen Partikel bestehen aus einem NaYF4:Yb,Er-Kern, dotiert mit 18 % Yb3+ und 2 % Er3+, und einer inerten Schale aus NaYF4, wobei die Dicke der Schale dem jeweiligen Radius des Kernpartikels entspricht. Absolutmessungen der Photolumineszenz-Quantenausbeuten bei verschiedenen Anregungsleistungsdichten zeigen, dass die Quantenausbeuten von 45 nm Kern/Schale-Partikeln schon fast an die Quantenausbeute des mikrokristallinen aufwärtskonvertierenden Leuchtstoffs heranreichen. Kleinere Kern/Schale-Partikel, die nach der gleichen Methode hergestellt wurden, zeigen nur eine moderate Abnahme der Quantenausbeute. Beispielsweise ist die Quantenausbeute von 15 nm großen Kern/Schale-Partikeln bei hohen Leistungsdichten (100 W cm−2) nur um einen Faktor drei kleiner als die des mikrokristallinen Leuchtstoffpulvers und um ungefähr einen Faktor 10 kleiner bei niedrigen Leistungsdichten (1 W cm−2). Wiley VCH Verlag 2018 Angewandte Chemie 130 28 8901 8905 10.1002/ange.201803083 2018-07-25 OPUS4-45574 Zeitschriftenartikel Homann, C.; Krukewitt, Lisa; Frenzel, Florian; Grauel, Bettina; Würth, Christian; Resch-Genger, Ute; Haase, M. NaYF4:Yb,Er/NaYF4 Core/Shell Nanocrystals with High Upconversion Luminescence Quantum Yield Upconversion core/shell nanocrystals with different mean sizes ranging from 15 to 45 nm were prepared via a modified synthesis procedure based on anhydrous rare-earth acetates. All particles consist of a core of NaYF4:Yb,Er, doped with 18 % Yb3+ and 2 % Er3+, and an inert shell of NaYF4, with the shell thickness being equal to the radius of the core particle. Absolute measurements of the photoluminescence quantum yield at a series of different excitation power densities show that the quantum yield of 45 nm core/shell particles is already very close to the quantum yield of microcrystalline upconversion phosphor powder. Smaller core/shell particles prepared by the same method show only a moderate decrease in quantum yield. The quantum yield of 15 nm core/shell particles, for instance, is reduced by a factor of three compared to the bulk upconversion phosphor at high power densities (100 W cm−2) and by approximately a factor of 10 at low power densities (1 W cm−2). Wiley-VCH 2018 Angewandte Chemie - International Edition 57 28 8765 8769 10.1002/anie.201803083 2018-07-25 OPUS4-50698 Vortrag Frenzel, Florian Spectroscopic study of plasmon enhanced UPCON luminescence of silica-metal core-shell nanocomposites - status report The presentation focuses on the current state of the optical spectroscopic studies on plasmon enhanced upconversion luminescent processes of silica-metal core-shell nanocomposites. A general introduction of the upconversion process, the theoretical basis of plasmonic enhancement, the theoretical requirements in regard to NP architecture for plasmon enhanced UC will be outlined. The first proof-of-concept measurements show the difficulty in realization the theoretical measurement parameters in laboratory conditions and underline the need for shifting the experiments to single particle level." 2017 Gruppenseminar der Nanooptik an der HU Berlin, Prof. Benson, Institut für Physik, Raum 1‘404 Berlin, Germany 09.05.2017 2020-04-27 OPUS4-48608 Zeitschriftenartikel Wiesholler, L. M.; Frenzel, Florian; Grauel, Bettina; Würth, Christian; Resch-Genger, Ute; Hirsch, T. Resch-Genger, Ute; Hirsch, Thomas Yb,Nd,Er-doped upconversion nanoparticles: 980 nm versus 808 nm excitation Yb,Nd,Er-doped upconversion nanoparticles (UCNPs) have attracted considerable interest as luminescent reporters for bioimaging, sensing, energy conversion/shaping, and anticounterfeiting due to their capability to convert multiple near-infrared (NIR) photons into shorter wavelength ultraviolet, visible or NIR luminescence by successive absorption of two or more NIR photons. This enables optical measurements in complex media with very little background and high penetration depths for bioimaging. The use of Nd3+ as substitute for the commonly employed sensitizer Yb3+ or in combination with Yb3+ shifts the excitation wavelength from about 980 nm, where the absorption of water can weaken upconversion luminescence, to about 800 nm, and laser-induced local overheating effects in cells, tissue, and live animal studies can be minimized. To systematically investigate the potential of Nd3+ doping, we assessed the performance of a set of similarly sized Yb3+,Nd3+,Er3+-doped core- and core-shell UCNPs of different particle architecture in water at broadly varied excitation power densities (P) with steady state and time-resolved fluorometry for excitation at 980 nm and 808 nm. As a measure for UCNPs performance, the P-dependent upconversion quantum yield (Φ) and its saturation behavior were used as well as particle brightness (B). Based upon spectroscopic measurements at both excitation wavelengths in water and in a lipid phantom and B-based calculations of signal size at different penetration depths, conditions under which excitation at 808 nm is advantageous are derived and parameters for the further optimization of triple-doped UCNPs are given. London Royal Society of Chemistry Royal Society of Chemistry 2019 Nanoscale 11 28 13440 13449 10.1039/C9NR03127H 2019-08-02 OPUS4-52364 Zeitschriftenartikel Frenzel, Florian; Würth, Christian; Dukhno, O.; Przybilla, F.; Wiesholler, L. M.; Muhr, V.; Horsch, T.; Mély, Y.; Resch-Genger, Ute Multiband emission from single β-NaYF4(Yb,Er) nanoparticles at high excitation power densities and comparison to ensemble studies Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core-shell β-NaYF4:Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb3+ and 1% or 3% Er3+ performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er3+ levels at P > 1 kW/cm2. This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm2, the increasing population of higher Er3+ energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2-3, 3-4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er3+ levels. Nano Research 2021 Springer 14 11 4107 4115 10.1007/s12274-021-3350-y 2021-03-31 OPUS4-47230 Zeitschriftenartikel Saleh, Maysoon I.; Panas, I.; Frenzel, Florian; Würth, Christian; Rühle, Bastian; Slominskii, Y.; Demchenko, A.; Resch-Genger, Ute Sensitization of upconverting nanoparticles with a NIR-emissive cyanine dye using a micellar encapsulation approach Photon upconversion nanomaterials have a wide range of applications, including biosensing and deep-tissue imaging. Their typically very weak and narrow absorption bands together with their size dependent luminescence efficiency can limit their application potential. This has been addressed by increasingly sophisticated core-shell particle architectures including the sensitization with organic dyes that strongly absorb in the near infrared (NIR). In this work, we present a simple water-dispersible micellar system that features energy transfer from the novel NIR excitable dye, 1859 SL with a high molar absorption coefficient and a moderate fluorescence quantum yield to oleate-capped NaYF4:20%Yb(III), 2%Er(III) upconversion nanoparticles (UCNP) upon 808 nm excitation. The micelles were formed using the surfactants Pluronic F-127 and Tween 80 to produce a hydrophilic dye-UCNP system. Successful energy transfer from the dye to the UCNP could be confirmed by emission measurements that revealed the occurrence of upconversion emission upon excitation at 808 nm and an enhancement of the green Er(III) emission compared to direct Er(III) excitation at 808 nm. IOP 2019 Methods and applications in fluorescence 7 1 (Special issue: Upconversion Methods, Applications and Materials) 014003-1 014003-9 urn:nbn:de:kobv:b43-472300 10.1088/2050-6120/aafe1f https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2019-01-22 OPUS4-46076 Zeitschriftenartikel Tietze, R.; Panzer, R.; Starzynski, T.; Guhrenz, C.; Frenzel, Florian; Würth, Christian; Resch-Genger, Ute; Weigand, Jan J.; Eychmüller, A. Synthesis of NIR-emitting InAs-based core/shell quantum dots with the use of tripyrazolylarsane as arsenic precursor Tris(3,5-dimethylpyrazolyl)arsane (1) is introduced as a low-cost and convenient to handle arsenic precursor for the straight Forward synthesis of InAs Quantum dots (QDs). Transamination of 1 with the solvent oleylamine (OLAH) gives trioleylarsane (As(OLA)3) which in the presence of the reducing agents diisobutylaluminum hydride (DIBAL-H) or trioleylphosphane (P(OLA)3) yields InAs QDs via a typical hot injection approach. The size of the obtained InAs core QDs are tuned by varying the reaction time, the amount of the applied reducing agent, or even more effectively by changing the Indium and/or zinc halide precursors, InX3, and ZnX2 (Cl, Br, or I). Passivation of the resulting InAs particles with a protective ZnS or ZnSe shell results in improved photoluminescence of the core/shell QDs covering a spectral range between 600 and 1150 nm. Wiley 2018 Particle & Particle Systems Characterization 35 9 1800175, 1 7 10.1002/ppsc.201800175 2018-09-28 OPUS4-46370 Zeitschriftenartikel Meijer, M. S.; Rojas-Gutierrez, P. A.; Busko, D.; Howard, I. A.; Frenzel, Florian; Würth, Christian; Resch-Genger, Ute; Richards, B. S.; Turshatov, A.; Capobianco, J. A.; Bonnet, S. Absolute upconversion quantum yields of blue-emitting LiYF4:Yb3+,Tm3+ upconverting nanoparticles The upconversion quantum yield (QY) is an essential parameter for the characterization of the optical performance of lanthanoid-doped upconverting nanoparticles (UCNPs). Despite its nonlinear dependence on excitation power density, it is typically reported only as a single number. Here, we present the first measurement of absolute upconversion quantum yields of the individual emission bands of blue light-emitting LiYF4:Yb3+,Tm3+ UCNPs in toluene. Reporting the quantum yields for the individual emission bands is required for assessing the usability of UCNPs in various applications that require upconverted light of different wavelengths, such as bioimaging, photocatalysis and phototherapy. Here, the reliability of the QY measurements is demonstrated by studying the same batch of UCNPs in three different research groups. The results show that whereas the total upconversion quantum yield of these UCNPs is quite high - typically 0.02 at a power density of 5 W/cm2 — most of the upconverted photon flux is emitted in the 794 nm upconversion band, while the blue emission band at 480 nm is very weak, with a much lower quantum yield of 6 times 10^5 at 5 W/cm2. Overall, although the total upconversion quantum yield of LiYF4:Yb3+,Tm3+ UCNPs seems satisfying, notably for NIR bioimaging, blue-light demanding phototherapy applications will require better-performing UCNPs with higher blue light upconversion quantum yields. Royal Society of Chemistry 2018 Physical chemistry, chemical physics : PCCP 20 35 22556 22562 10.1039/c8cp03935f 2018-10-25 OPUS4-41172 Posterpräsentation Frenzel, Florian Power dependent optical properties of hexagonal β-NaYF4: x % Er3+, 20 % Yb3+ core/ core-shell upconversion nanoparticles in cyclohexane and water Lanthanide doped photon upconverting nanophosphors (UCNPs) have the unique capability to produce narrow band, multi-color emission in the UV/vis/NIR upon multiphotonic absorption of infrared light, which makes them promising reporters for diagnostic, bioanalytical, and biological applications. This minimizes background signals, which normally occur due to autofluorescence from auxochromes, in biological matrices and enables deep penetration depths in biological applications. Moreover, UCNPs show long luminescence lifetimes in the μs range favorable for time gated emission in conjunction with a high photostability and chemical inertness and they do not blink. One of the most efficient upconversion (UC) phosphors for conversion of 976 nm to 655 nm and 545 nm light presents the hexagonal NaYF4-host crystal doped with 20 % Yb3+ used as sensitizer to absorb infrared light and 2 % Er3+ acting as activator mainly responsible for light emission. The high transparency in the relevant spectral windows of this host together with its low phonon frequencies ensure relatively high luminescence efficiencies. Although UCNPs are ideal candidates for many chemical and biological sensing and imaging applications, compared to other well-known chromophores like organic dyes or QDs, they suffer from a comparatively low brightness due to the low absorption cross sections of the parity forbidden f-f-transitions and low photoluminescence quantum yields (QYUC) particularly in the case of small nanoparticles with sizes of < 50 nm. The rational design of more efficient UCNPs requires an improved understanding of the nonradiative decay pathways in these materials that are influenced by particle architecture including dopant ion concentration and homogeneity of dopant distribution within UCNPs, size/surface-to-volume ratio, surface chemistry, and microenvironment. A promising approach to overcome the low efficiency of UCNPs is to use plasmonic interactions between a noble metal (Ag or Au) structure in the proximity of UCNPs and the incident light. This interaction leads to a modification of the spectroscopic properties due to local field enhancements and can involve an increase of the photoluminescence. In this respect, we study the interactions of UCNPs with metal structures (clusters and shells) by varying shape and size. Here, first results derived from integrating sphere spectroscopy and time-resolved fluorescence measurements are presented. 2017 Summer School "EXCITING NANOSTRUCTURES" Bad Honnef, Germany 17.07.2017 21.07.2017 2017-07-31 OPUS4-58238 Posterpräsentation Resch-Genger, Ute; Pauli, J.; Güttler, Arne; Richter, Maria; Fiedler, Saskia; Frenzel, Florian; Wegner, Karl-David; Würth, Christian Photoluminescence Quantum Yields of Luminescent Nanocrystals and Particles in the UV/vis/NIR/SWIR The rational design of functional luminescent materials such as semiconductor quantum dots and lanthanide-based upconversion nanoparticles, all photophysical and mechanistic studies, and the comparison of different emitters require accurate and quantitative photoluminescence measurements. Particularly the reliable determination of the key performance parameter photoluminescence quantum yield (f), the number of emitted per absorbed photons, and the brightness are of special importance for luminescence applications in the life and material sciences and nano(bio)photonics.[1] In this context, examples for absolute measurements of the photoluminescence quantum yields of UV/vis/NIR/SWIR emissive semiconductor quantum dots and rods, made from different materials, and spectrally shifting lanthanide upconversion nanocrystals with different surface chemistries in transparent matrices are presented including excitation wavelength and power density dependent studies utilizing integration sphere spectroscopy.[2,3] In addition, procedures for the absolute determination of the photoluminescence quantum yields of scattering dispersions of larger size quantum rods and differently sized inorganic particles have been developed as well as procedures for the characterization of solid luminescent nanomaterials such as different perovskites and YAG:Cer converter materials.[4] Thereby, challenges and pitfalls of f measurements in different wavelength regions including the SWIR and material-specific effects related to certain emitter classes are addressed, achievable uncertainties are quantified, and relative and absolute measurements of photoluminescence quantum yield measurements are compared to underline limitations of the former approach. Finally, a set of novel UV/vis/NIR quantum yield standards is presented including their certification with a complete uncertainty budget.[5] 2023 NANAX 10 Klosterneuburg, Austria 03.07.2023 07.07.2023 2023-09-14