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Nickel Sulphide Coated Reduced Graphene Oxide As Cathode For Dye-Sensitized Solar Cells
1IMEN, UKM, Bangi, Selangor, Malaysia
2Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
3Institute of Microengineering and Nanoelectronics (IMEN),, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
4Research Center for Nanotechnology Systems, National Research and Innovation Agency (BRIN), Tangerang Selatan, Banten, Indonesia
*Email Address : mohd.yusri@ukm.my
Abstract : This work is concerned on the preparation of nickel sulphide-reduced graphene oxide (NiS/rGO) films employed as cathode in dye-sensitized solar cell (DSSC). A novel aspect of this study involves employing NiS/rGO films as cathodes to replace Pt and pure rGO film, resulting in Pt-free cathode for DSSC. The main problem is Pt is a costly cathode and the efficiency of rGO-based device is low. The main objective of this work is to investigate the effect of nickel chloride (NiCl2) concentration, thiourea concentration and annealing temperature on the properties of NiS/rGO and the device efficiency. The properties include surface morphology, elemental analysis, phase structure, optical transmission, chemical bonding and sheet resistance. Graphene oxide (GO) was initially prepared using modified Hummers’ method. Subsequently, reduced GO underwent ultrasonication and NiS was coated on rGO by spin-coating technique. The sample prepared at 0.06 M NiCl2 exhibits the highest efficiency (ƞ) of 1.03% caused by long lifetime (τ) of 4.94 ms. The XRD analysis indicates the coexistence of rGO and NiS phases in all samples with various NiCl2 concentrations. The films morphology is characterized by white strips and sphere agglomeration, corresponding to rGO and NiS, respectively. rGO consists of conductive and non-conductive region represented by white strips and dark region, respectively. The use of 1.20 M thiourea concentration yielded the highest short-circuit current density (Jsc) and highest ƞ of 5.55 mA/cm2 and 1.42%, respectively. The NiS/rGO-based device exhibits 215% improvement in efficiency compared to the pure rGO-based device. The incorporation of NiS on rGO led to a 37.86% enhancement in the efficiency, primarily attributed to long lifetime (τ) (293.16 ms). The annealing temperature of 380 oC resulted in the highest ƞ of 0.50%, primarily due to the low sheet resistance of 12.86 Ω. The findings suggest that NiS/rGO has potential as an alternative cathode in DSSC
Keywords : cathode, dye-sensitized solar cell, nickel sulphide, reduced graphene oxide