Abstract:
Photovoltaic technology is a very crucial technology and it is gradually growing worldwide
as there is plenty of sunshine daily especially in African countries. The aim of photovoltaic
technology is to generate electricity from solar power using photovoltaic devices like solar
(photovoltaic) cells. Photovoltaic cells are mostly used to provide electricity in rural areas
which are not connected to the national grid like farms (cattle posts). In this work superstrate
CZTS solar cells (Cell-A and Cell-B) were fabricated from optimised CZTS absorber layers
and In2S3 buffer layer by a cost-effective spray pyrolysis technique. Firstly, CZTS absorber
layers were grown on borosilicate glass substrates from various precursor solutions and their
properties were studied through X-ray diffraction, Raman spectroscopy, UV-Vis
spectroscopic analysis, Hall measurement, and Scanning electron microscopy. X-ray
diffraction results revealed similar patterns for all samples that are three peaks: (1 1 2), (2 2
0), and (2 1 2) belonging to kesterite CZTS with tetragonal structure. All thin films were
growing along (1 1 2) plane. Results obtained via Raman spectroscopy revealed two wide
peaks at 248 cm-1
and 331 cm-1
in all thin films. Both peaks belonging to CZTS with
tetragonal structure. Both the X-ray diffraction and the Raman spectrometry results revealed
that samples prepared from solutions containing tin (IV) chloride were highly crystalline. The
maximum absorbance obtained for all thin films was between 1.5 and 4 in the visible and
near infrared region. Unlike crystallinity, the absorbance was high for samples that were
prepared from solutions containing tin (II) chloride as a tin source. As revealed by the Hall
measurement, the resistivity of the thin films was ranging from 2.84 x 10-2 Ωcm to 3.29 x 10-1
Ωcm and the sample with the lowest resistivity (labelled as CZTS003) was prepared from a
solution containing copper (II) chloride, zinc acetate, tin (IV) chloride and thiourea solutions.
The SEM micrographs showed well defined grains for all thin films except the one that was
prepared from a solution containing copper (II) chloride, zinc nitrate, tin (IV) chloride and
thiourea. A sample that had the lowest resistivity also exhibited the largest grains.
In the second part of this work, In2S3 buffer layers were also deposited on glass substrates
from a mixture of indium chloride solution and thiourea solution. The concentration of
indium chloride solution was held constant and the concentration of thiourea was varied
between 0.090 M and 0.105 M in steps of 0.005 M. After deposition, the thin films were
characterised via X-ray diffraction, Raman spectrometry, UV-Vis spectroscopy, Atomic
Force Microscopy, and Hall measurement. The results obtained by X-ray diffraction revealed
xv
polycrystalline β-In2S3, and the increased concentration of thiourea lead to decreased
crystallinity of the thin films. Similar Raman spectra of all thin films was obtained via Raman
spectroscopy. The two peaks found at 306 cm-1
and 365 cm-1
on the Raman spectra belong to
β-In2S3. All the thin films exhibited similar transmittance spectra, and the transmittance of the
thin films was lying between 60 % and 80 % in the visible and near infrared region of the
electromagnetic spectrum. Transmittance was highest in the visible region for the sample
prepared from solution containing 0.095 M of thiourea solution. In addition, the thin films
had wide optical band gaps lying between 2.75 eV and 3.0 eV. The electrical resistivity of
In2S3 thin-film layers increased from 5.6249 x 10-2 Ωcm to 4.0953 Ωcm when concentration
of thiourea solution was increased from 0.090 M to 0.100 M, however, when the
concentration was further increased to 0.105 M the resistivity of the In2S3 thin film layers
decreased.
The performance of fabricated solar cells (denoted as Cell-A prototype and Cell-B prototype)
was studied. Cell-A prototype performed better than Cell-B prototype, because the efficiency
at maximum power point of Cell-A was 0.158 % while the efficiency at the maximum power
point of Cell-B was 0.07 %. In addition, Cell-A exhibited higher open-circuit voltage and
short-circuit current density compared to Cell-B. The open-circuit voltage and short-circuit
current density of Cell-A were 200 mV and 2.26 mA/cm2
, respectively, while Cell-B had
shown open-circuit voltage of 80mV and short-circuit current density of 1.75 mA/cm2
.
Mompoloki, K (2024). Investigation of cu2znsns4 (caus) nanostructured material system for energy conversion. Afribary. Retrieved from https://track.afribary.com/works/investigation-of-cu2znsns4-caus-nanostructured-material-system-for-energy-conversion
Mompoloki, Kefositse "Investigation of cu2znsns4 (caus) nanostructured material system for energy conversion" Afribary. Afribary, 30 Mar. 2024, https://track.afribary.com/works/investigation-of-cu2znsns4-caus-nanostructured-material-system-for-energy-conversion. Accessed 27 Nov. 2024.
Mompoloki, Kefositse . "Investigation of cu2znsns4 (caus) nanostructured material system for energy conversion". Afribary, Afribary, 30 Mar. 2024. Web. 27 Nov. 2024. < https://track.afribary.com/works/investigation-of-cu2znsns4-caus-nanostructured-material-system-for-energy-conversion >.
Mompoloki, Kefositse . "Investigation of cu2znsns4 (caus) nanostructured material system for energy conversion" Afribary (2024). Accessed November 27, 2024. https://track.afribary.com/works/investigation-of-cu2znsns4-caus-nanostructured-material-system-for-energy-conversion