Recycling of Waste CdS Film Solar Cells by Different Depositions
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Date
2020-12-24
Authors
صبيح, مجد إبراهيم راشد
Journal Title
Journal ISSN
Volume Title
Publisher
An-Najah National University
Abstract
Nano-sized CdS films were deposited onto ITO/Plastic substrates for
the first time by different techniques, namely: electrochemical (ECD),
chemical bath (CBD) and electrochemical followed by chemical bath
(ECD/CBD) deposition techniques. Scanning electron microscopy (SEM),
X-Ray diffraction (XRD), and electronic absorption spectra confirmed the
presence of CdS in the films. Photo-electrochemical (PEC) characteristics
of different films, such as photo (J-V) plots, conversion efficiency and
stability, were all investigated. Method of deposition and treatment affected
the CdS film characteristics.
PEC characteristics of different films showed different behaviors.
ECD films gave a CdS film that was too thin to be characterized.
ECD/CBD films showed lower light-to-electricity conversion efficiency
than CBD films. Moreover, the CBD films, which were prepared through
the fourth cycle of deposition showed higher values of conversion
efficiency and stability than other counterparts. This shows how
advantageous the new described films are. Coating the CBD-CdS film with
multi-wall carbon nanotube (MWCNT) did not improve its PEC
characteristics.
XVIII
The effect of redox couple on the photo J-V plots was measured for
fresh CBD- CdS thin film electrodes. The most efficient redox couple was
the Poly-Sulfide system, which showed higher efficiency than the iron
redox couple. Therefore, the Poly-Sulfide redox couple was used
throughout this work.
Due to the hazardous nature of Cd ions, and their negative impact on
the environment, this work described how the waste CdS films can be
recycled into useful films. Again ITO/Plastic substrates were used for
recycling the CdS films using CBD.
The effect of annealing (125 ºC), and cooling rate (slow & fast), on
fresh CdS film characteristics, such as electronic absorption spectra was
studied. Different film PEC characteristics, such as photo (J-V) plots, open circuit voltage (Voc), short photo-current density (Jsc), efficiency and
stability, were also studied. Films treated by annealing & fast cooling
showed higher conversion efficiency and stability than non-annealed ones.
The recycled CdS film showed lower PEC efficiency when annealed 125
ºC under N2, despite the cooling rate.