Presentation
30 May 2022 Photothermal techniques for ultraprecise measurements of the photoluminescence quantum yield of molecular emitters in solution
Sigurd Mertens, Koen Vandewal
Author Affiliations +
Abstract
Several emerging applications relying on absorption and re-emission of light by molecular species require a photo-luminescence quantum yield (PLQY) near unity. However, when the PLQY approaches unity and the optical density is low, it is surprisingly difficult to measure accurately, as the most commonly used techniques rely either on exact knowledge of material parameters or on a comparison to a measurement of a non-fluorescent material, introducing errors in the measurement, further complicated by possible non-linearities of the detection system. In this work, we propose a new setup which circumvents these issues. It involves a simultaneous relative measurement of the produced heat, the amount of re-emitted light and the average energy of the emitted photons, allowing us to determine the fraction of absorbed energy which is converted to heat. Crucial to the set-up is a tunable continuous-wave laser, allowing to perform these measurements at varying excitation energies. The photon energy dependent part of the fraction of absorbed energy converted to heat is due to an increased thermalization energy with increasing incident photon energy. The remaining heat produced by the fully thermalized excitation determines the fraction of absorbed energy not converted to photons and thus the deviation of the PLQY from unity. Using this new method, we determine the PLQY of seven different luminescent molecules in low concentration solutions, and use a rigorous error analysis to achieving PLQY measurements with an unprecedented accuracy down to ±0.3% within 95% confidence intervals. Perylene orange is found to have the highest PLQY of the molecules studied, being 99.0±0.3%.
Conference Presentation
© (2022) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sigurd Mertens and Koen Vandewal "Photothermal techniques for ultraprecise measurements of the photoluminescence quantum yield of molecular emitters in solution", Proc. SPIE PC12149, Organic Electronics and Photonics: Fundamentals and Devices III, PC121490U (30 May 2022); https://doi.org/10.1117/12.2624250
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KEYWORDS
Quantum efficiency

Luminescence

Photons

Molecules

Integrating spheres

Radiometry

Solar concentrators

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