63830 2025 eng 1 8 article ACS Publications 1 -- -- -- For a series of 500 μm-thick polyurethane films containing different concentrations of luminescent and scattering YAG:Ce microparticles, we systematically explored and quantified pitfalls of absolute measurements of photoluminescence quantum yields (Φf) for often employed integrating sphere (IS) geometries, where the sample is placed either on a sample holder at the bottom of the IS surface or mounted in the IS center. Thereby, the influence of detection and illumination geometry and sample position was examined using blanks with various scattering properties for measuring the number of photons absorbed by the sample. Our results reveal that (i) setup configurations where the scattering sample is mounted in the IS center and (ii) transparent blanks can introduce systematic errors in absolute Φf measurements. For strongly scattering, luminescent samples, this can result in either an under- or overestimation of the absorbed photon flux and hence an under- or overestimation of Φf. The size of these uncertainties depends on the scattering properties of the sample and instrument parameters, such as sample position, IS size, wavelength-dependent reflectivity of the IS surface coating, and port configuration. For accurate and reliable absolute Φf measurements, we recommend (i) a blank with scattering properties closely matching those of the sample to realize similar distributions of the diffusely scattered excitation photons within the IS, and (ii) a sufficiently high sample absorption at the excitation wavelength. For IS setups with center-mounted samples, measurement geometries should be utilized that prevent the loss of excitation photons by reflections from the sample out of the IS. Analytical chemistry 10.1021/acs.analchem.4c06726 1520-6882 urn:nbn:de:kobv:b43-638304 publish 31.07.2025 false true Creative Commons - CC BY - Namensnennung 4.0 International F. Frenzel S. Fiedler A. Bardan Arne Güttler Christian Würth Ute Resch-Genger eng uncontrolled Quality assurance eng uncontrolled Fluorescence eng uncontrolled Nano eng uncontrolled Particle eng uncontrolled Quantum yield eng uncontrolled Characterization eng uncontrolled Silica eng uncontrolled Scattering eng uncontrolled Uncertainty eng uncontrolled Film eng uncontrolled Pphosphor eng uncontrolled YAG:Ce eng uncontrolled LED eng uncontrolled Converter material eng uncontrolled Solid material eng uncontrolled Polymer eng uncontrolled Composite material eng uncontrolled Advanced material Analytische Chemie Ingenieurwissenschaften und zugeordnete Tätigkeiten Sanitär- und Kommunaltechnik; Umwelttechnik 1 Analytische Chemie; Referenzmaterialien 1.2 Biophotonik Umwelt Material Chemie und Prozesstechnik Chemische Charakterisierung und Spurenanalytik Verlagsliteratur Datei für die Öffentlichkeit verfügbar ("Open Access") Wissenschaftliche Artikel der BAM Advanced Materials Bundesanstalt für Materialforschung und -prüfung (BAM) https://opus4.kobv.de/opus4-bam/files/63830/Infl. of Measurem. Geom. a. Blank on abslt. Measurem. of Photolum. QY of Scatterg Lum. Films.pdf