Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.

In this article, we present a method to determine the bandgap of a thermochromic phosphor film by simple reflectance measurements under controlled heating. The phosphor is illuminated by a light-emitting diode while being heated continuously. The reflected light is detected using a calibrated photod...

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Main Author: Rwabona, Katashaya Steven
Format: Article
Published: Kabale University 2024
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Online Access:http://hdl.handle.net/20.500.12493/2299
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author Rwabona, Katashaya Steven
author_facet Rwabona, Katashaya Steven
author_sort Rwabona, Katashaya Steven
collection KAB-DR
description In this article, we present a method to determine the bandgap of a thermochromic phosphor film by simple reflectance measurements under controlled heating. The phosphor is illuminated by a light-emitting diode while being heated continuously. The reflected light is detected using a calibrated photodiode circuit based on an operational transconductance amplifier. We apply the Schuster- Kubelka-Munk function to deduce the absorbance over temperature and thus the bandgap. We show, for the first time, that the thermochromic phosphor's colour change follows Arrhenius's Law and therefore involves activation energy. We estimate the bandgap to be between 1.1 eV and 1.9 eV and find an activation energy of 46.67 ±1.6 kJ/mol. The simplicity of the approach will appeal to undergraduate teachers and students of physics and materials science. The technique can be used to investigate other thermochromic materials as well.
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spelling oai:idr.kab.ac.ug:20.500.12493-22992024-09-07T00:00:46Z Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating. Rwabona, Katashaya Steven Reflectance Absorbance Thermochromism Phosphors Bandgap Activation energy In this article, we present a method to determine the bandgap of a thermochromic phosphor film by simple reflectance measurements under controlled heating. The phosphor is illuminated by a light-emitting diode while being heated continuously. The reflected light is detected using a calibrated photodiode circuit based on an operational transconductance amplifier. We apply the Schuster- Kubelka-Munk function to deduce the absorbance over temperature and thus the bandgap. We show, for the first time, that the thermochromic phosphor's colour change follows Arrhenius's Law and therefore involves activation energy. We estimate the bandgap to be between 1.1 eV and 1.9 eV and find an activation energy of 46.67 ±1.6 kJ/mol. The simplicity of the approach will appeal to undergraduate teachers and students of physics and materials science. The technique can be used to investigate other thermochromic materials as well. 2024-09-06T11:45:40Z 2024-09-06T11:45:40Z 2024 Article Rwabona, Katashaya Steven (2024). Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating. Kabale: Kabale University. http://hdl.handle.net/20.500.12493/2299 Attribution-NonCommercial-NoDerivs 3.0 United States http://creativecommons.org/licenses/by-nc-nd/3.0/us/ application/pdf Kabale University
spellingShingle Reflectance Absorbance Thermochromism Phosphors Bandgap Activation energy
Rwabona, Katashaya Steven
Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.
title Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.
title_full Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.
title_fullStr Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.
title_full_unstemmed Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.
title_short Determining Bandgap of Thermochromic Phosphor Films via Reflectance Measurements under Controlled Heating.
title_sort determining bandgap of thermochromic phosphor films via reflectance measurements under controlled heating
topic Reflectance Absorbance Thermochromism Phosphors Bandgap Activation energy
url http://hdl.handle.net/20.500.12493/2299
work_keys_str_mv AT rwabonakatashayasteven determiningbandgapofthermochromicphosphorfilmsviareflectancemeasurementsundercontrolledheating