Frontiers in Materials Characterisation towards Industrial Translation (FRIMACHAT), 11 - 13 July 2017
Solarstrahlung: Wirkung, Anwendung, Messung und Simulation, 22. DAfP-Symposium in Freiburg | 18. - 19. Mai 2017
Fortbildungskurs "Anorganische Leuchtstoffe & LEDs", Frankfurt | 24. - 25. April 2017
Phosphor Global Summit and Quantum Dots Forum, La Jolla (CA), USA | 13 - 17 March 2017
The Phosphor Global Summit takes place in changing US cities every year in March. Since 2006, Prof. Jüstel has been chairman of this conference.
Cathodoluminescence and photoluminescence of praseodymium doped UV-emitting phosphors
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The UV-C emitting materials YPO4:Bi, YPO4:Pr, YBO3:Pr and Y2SiO5:Pr are well known for their capability to efficiently convert Vacuum-UV radiation produced in Xenon-Excimer-Luminaires. Unfortunately, such UV-C sources suffer from a poor long-term stability, mainly due to a fast aging of the applied phosphor materials, caused by a direct contact to the Xenon excimer discharge within the coated discharge vessel. The following publication, for the first time, describes the spectroscopic analysis of the above mentioned materials under electron beam excitation. It thereby offers conclusions onto the efficiency of these materials upon excitation with an alternative excitation source.
M. Broxtermann, D. den Engelsen, G. R. Fern, P. Harris, T. G. Ireland, T. Jüstel, J. Silver: Cathodoluminescence and Photoluminescence of YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+, and YPO4:Bi3+, ECS J. Solid State Sci. Technol. 6, R47-R52 (2017), doi: 10.1149/2.0051704jss
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Is it possible to squeeze multiple functionial units into a box of only 5 nm diameter? Krzysztof Gugula has done just that: he designed fluorescent nanoparticles composed of three different components. This gave him the freedom to realize inside these particles fluorescence from the band edge as well as from defects. Employing well-balanced heat treatment, he was able to adjust the relative contributions in order to fine-tune the colour of the emitted light. Such versatile systems may prove to be useful for instance in white LEDs with very high colour quality.
K. Guguła, M. Entrup, L. Stegemann, S. Seidel, R. Pöttgen, C.A. Strassert, M. Bredol: Solid solution quantum dots with tunable dual- or ultra-broadband emission for LEDs, ACS Appl. Mater. Interfaces 9, 521-528 (2017), doi: 10.1021/acsami.6b08190
Structure also in the smallest volumes
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"Quantum dots" are semiconductor particles with diameters below 20 nm, useful for a variety of optical applications, e.g. in novel "quantum TVs". The reliable fabrication of such small objects is still a challenge - especially when these particles need to have a complex chemical composition and a well-defined internal structure. Julia Zimdars, working in the Bredol group, has now demonstrated, how Zn(S,Se):Mn nanoparticles can be produced by relatively simple wet chemical methods, with uniform size and shape and a diameter of ca. 7nm. These particles not only show intensive fluorescence, but also contain an internal structure, in which the contents of sulfur and selenium can be adjusted in the core and at the surface.
J. Zimdars, J. Pilger, M. Entrup, D. Deiting, A.H. Schäfer, M. Bredol: A facile synthesis of alloyed Mn-doped ZnSeS nanoparticles using a modified selenium/sulfur precursor in a one-pot approach, New J. Chem. 40, 8465-8470 (2016), doi: 10.1039/C6NJ01493C --> Paper