Effect of nickel in TiO2-SiO2-GO-based DSSC by using a sol-gel method

Abstract

A series of dye-sensitized solar cell (DSSC) TiO2-(SiO2)100-xNix-GO (TSN) (x = 0.0, 2.5, 5.0, 7.5) films were successfully prepared using a sol-gel method via doctor-blade technique. Tetraethyl-orthosilicate (TEOS), absolute ethanol (C2H5OH), deionized water, and acid ammonia were mixed in one solution. Nickel (II) nitrate hexahydrate (Ni(NO3)2.6H2O) and diethanolamine were added to the prepared solution to produce the precursor of (SiO2)100-xNix. This work is to determine the influence of Ni2+ in the TiO2-SiO2-GO-based DSSC performances. The films were prepared by SiO2 amorphous without Ni2+ and added with Ni2+ at 2.5, 5.0, and 7.5%, respectively. The crystal structure and morphology properties of the films were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy dispersion X-ray. FESEM images showed the amount of Ni2+ was found to increase the grain growth of TSN2.5 and TSN7.5 films ranging from 30.14 to 40.19 nm and 48.01 to 77.04 nm, respectively. The structural characteristics of TiO2-(SiO2)100-xNix-GO are confirmed as anatase phase and belong to TiO2 with a characteristic peak of (101) as a predominant peak. The photovoltaic performances were analyzed using J–V measurement and electrochemical impedance spectroscopy (EIS) to determine the factors that influence the performance of the DSSCs. Hence, this study suggests that the TSN7.5 films exhibited the highest cell performance, presenting a Jsc, Voc, FF, and cell efficiency of 20.52 mA/cm2, 0.230 V, 0.391, and 1.843%, respectively. TiO2-(SiO2)100-xNix-GO doped with 7.5% Ni provide larger diffusion rate, low recombination effect, and longer electron lifetime, thus enhancing the performance of DSSCs.