RGO-NiCo_2S_4 composite as a counter electrode for solid-state DSSC system with CuI as an electrolyte

摘要

The high and increasing demand for energy besides the limited stock of fossil fuel leads to searching for alternative energy. Solar energy is a potential renewable energy resource for replacing fossil fuel to produce energy. DSSC then becomes a good invention as it is easy to fabricate and relatively environmentally friendly. However, the efficiency is still lower; thus, further modification is needed. The DSSC was modified into Solid State DSSC to prevent leakage and corrosive behavior of liquid electrolytes in DSSC system. One of the promising materials to exchange the I~-/I_3- redox couple is CuI. In this research, the optimization of CuI concentration has been determined. The I V Keithley test showed that the highest efficiency achieved when the concentration of CuI is 0.05 M. On another hand, platinum that generally used counter electrode (CE) in DSSC system is expensive and low abundant in nature. Reduced graphene oxide (RGO), good conducting material, and abundant could be used as a counter electrode replacing the platinum. RGO was prepared from GO after the chemical exfoliation of graphite via modified Hummer's method. The reduction of GO was conducted by solvothermal reaction at 200 °C. Besides the preparation of RGO from GO reduction, the composite RGO-NiCo_2S_4 was also synthesized via hydrothermal with the addition of Ni, Co precursors, and thiourea. Materials characterization with XRD, FTIR, and SEM proofing that the synthesis of GO, RGO, and RGO-NiCo_2S_4 material was successfully achieved. Then, the graphene layers-based materials were then assembled as the counter electrode with the system of FTO/TiO_2-N_3/CuI/CE/FTO followed by I V test to compare the performance of each material. The results showed that the highest efficiency has been achieved when RGO-NiCo_2S_4 was used in the Solid State DSSC system.