Relation between Excitation Power Density and Er3+ Doping Yielding the Highest Absolute Upconversion Quantum Yield

Fischer, Stefan; Fröhlich, Benjamin; Krämer, Karl; Goldschmidt, Jan Christoph (2014). Relation between Excitation Power Density and Er3+ Doping Yielding the Highest Absolute Upconversion Quantum Yield. Journal of physical chemistry. C, 118(51), pp. 30106-30114. American Chemical Society 10.1021/jp510209x

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The upconversion quantum yield (UCQY) is one of the most significant parameters for upconverter materials. A high UCQY is essential for a succesful integration of upconversion in many applications, such as harvesting of the solar radiation. However, little is known about which doping level of the rare-earth ions yields the highest UCQY in the different host lattices and what are the underlying causes. Here, we investigate which Er3+ doping yields the highest UCQY in the host lattices β-NaYF4 and Gd2O2S under 4I15/2 → 4I13/2 excitation. We show for both host lattices that the optimum Er3+ doping is not fixed and it actually decreases as the irradiance of the excitation increases. To find the optimum Er3+ doping for a given irradiance, we determined the peak position of the internal UCQY as a function of the average Er−Er distance. For this purpose, we used a fit on experimental data, where the average Er−Er distance was calculated from the Er3+ doping of the upconverter samples and the lattice parameters of the host materials. We observe optimum average Er−Er distances for the host lattices β-NaYF4 and Gd2O2S with differences <14% at the same irradiance levels, whereas the optimum Er3+ doping are around 2× higher for β-NaYF4 than for Gd2O2S. Estimations by extrapolation to higher irradiances indicate that the optimum average Er−Er distance converges to values around 0.88 and 0.83 nm for β-NaYF4 and Gd2O2S, respectively. Our findings point to a fundamental relationship and focusing on the average distance between the active rare-earth ions might be a very efficient way to optimize the doping of rare-earth ions with regard to the highest achievable UCQY.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry
08 Faculty of Science > Department of Biology > Institute of Ecology and Evolution (IEE) > Behavioural Ecology

UniBE Contributor:

Fischer, Stefan and Krämer, Karl

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
500 Science > 590 Animals (Zoology)

ISSN:

1932-7447

Publisher:

American Chemical Society

Language:

English

Submitter:

Karl Krämer

Date Deposited:

09 Feb 2015 10:15

Last Modified:

26 Aug 2015 15:02

Publisher DOI:

10.1021/jp510209x

BORIS DOI:

10.7892/boris.62737

URI:

https://boris.unibe.ch/id/eprint/62737

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