TY - JOUR
T1 - Counting the photons
T2 - Determining the absolute storage capacity of persistent phosphors
AU - Van der Heggen, David
AU - Joos, Jonas J.
AU - Rodríguez Burbano, Diana C.
AU - Capobianco, John A.
AU - Smet, Philippe F.
N1 - Funding Information:
This work was financially supported by the agency for Innovation by Science and Technology (IWT) for a SBO-IWT grant (SBO130030) and by the UGent Special Research Fund (BOF) for a doctoral scholarship (BOF16/DOC/327).
Publisher Copyright:
© 2017 by the authors.
PY - 2017/7/28
Y1 - 2017/7/28
N2 - The performance of a persistent phosphor is often determined by comparing luminance decay curves, expressed in cd/m2. However, these photometric units do not enable a straightforward, objective comparison between different phosphors in terms of the total number of emitted photons, as these units are dependent on the emission spectrum of the phosphor. This may lead to incorrect conclusions regarding the storage capacity of the phosphor. An alternative and convenient technique of characterizing the performance of a phosphor was developed on the basis of the absolute storage capacity of phosphors. In this technique, the phosphor is incorporated in a transparent polymer and the measured afterglow is converted into an absolute number of emitted photons, effectively quantifying the amount of energy that can be stored in the material. This method was applied to the benchmark phosphor SrAl2O4:Eu,Dy and to the nano-sized phosphor CaS:Eu. The results indicated that only a fraction of the Eu ions (around 1.6% in the case of SrAl2O4:Eu,Dy) participated in the energy storage process, which is in line with earlier reports based on X-ray absorption spectroscopy. These findings imply that there is still a significant margin for improving the storage capacity of persistent phosphors.
AB - The performance of a persistent phosphor is often determined by comparing luminance decay curves, expressed in cd/m2. However, these photometric units do not enable a straightforward, objective comparison between different phosphors in terms of the total number of emitted photons, as these units are dependent on the emission spectrum of the phosphor. This may lead to incorrect conclusions regarding the storage capacity of the phosphor. An alternative and convenient technique of characterizing the performance of a phosphor was developed on the basis of the absolute storage capacity of phosphors. In this technique, the phosphor is incorporated in a transparent polymer and the measured afterglow is converted into an absolute number of emitted photons, effectively quantifying the amount of energy that can be stored in the material. This method was applied to the benchmark phosphor SrAl2O4:Eu,Dy and to the nano-sized phosphor CaS:Eu. The results indicated that only a fraction of the Eu ions (around 1.6% in the case of SrAl2O4:Eu,Dy) participated in the energy storage process, which is in line with earlier reports based on X-ray absorption spectroscopy. These findings imply that there is still a significant margin for improving the storage capacity of persistent phosphors.
UR - http://www.scopus.com/inward/record.url?scp=85026667362&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85026667362&partnerID=8YFLogxK
U2 - 10.3390/ma10080867
DO - 10.3390/ma10080867
M3 - Article
AN - SCOPUS:85026667362
SN - 1996-1944
VL - 10
JO - Materials
JF - Materials
IS - 8
M1 - 867
ER -