Photosensitization of ZnS nanoparticles with metal-free dye sensitizer based on Thiazole and Isatin derivatives for solid state dye sensitized solar cell
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Date
2025
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University of Namibia
Abstract
Zinc Sulphide (ZnS) is one of the wide band gap (Wurtzile; 3.91eV and Spalerite;
3.54eV) semiconductors suitable for application in dye-sensitized solar cell (DSSCs).
However, ZnS absorb UV light which only contribute about 5% total energy of solar
radiation. By sensitizing ZnS photo anode with dye sensitizer in DSSC, light
absorption is extended to visible regions (which contribute 43% total energy) of solar
radiation spectrum. Despite this, discovering the best photo anode materials (sensitizer
and semiconductor) remains a challenge in DSSCs. In this work, an experimental
study on the photosensitization of ZnS nanoparticles with five different metal-free
dyes was carried out. The ZnS nanoparticles and five different Thiazole and Isatin
based metal-free dyes were synthesized and characterized. Grafted ZnS-dye samples
were fabricated and characterized and the effect of solvatochromism on dyes on ZnS
were investigated. All data were collected from X-ray diffractometer (XRD), Proton
Nuclear Magnetic Resonance (1HNMR), Fourier Transform Infrared (FTIR)
spectroscopy and analyzed Ultraviolet and Visible light (UV-vis) spectroscopy. XRD
confirms that the crystal structure of the ZnS nanoparticles and the chemical structures
of dyes and their vibration frequencies were confirmed by 1HNMR and FTIR,
respectively. Among the five dyes, Dye1, Dye2 and Dye5 showed best photo response
before and after grafted on ZnS nanoparticles. Broad peaks and high absorption
intensities were observed on these dyes. Little or no absorption were observed for
Dye3 and Dye4 before and after grafted on ZnS nanoparticles
Description
A thesis submitted in fulfilment of the requirements for the degree of masters of science in Chemistry
Keywords
Photosensitization, Nanoparticles, Solvatochromism, Grafting, Characterization, Metal-free dyes, Namibia, University of Namibia