Impact of Ni metal ion concentration in TiO2 nanoparticles for enhanced photovoltaic performance of dye sensitized solar Cell

Abstract

The undoped and Ni-doped TiO2 (Ni\u2009=\u20090.1, 0.3, 0.5 M) are synthesized and analyzed for application as dye-sensitized solar cell. The structural, optical and surface properties of the prepared samples are investigated using XRD, FTIR, Raman, UV–Vis, BET and XPS. The morphology and elemental composition of the materials are also studied using FESEM and EDX. The fabricated dye-sensitized solar cells are analyzed using electrochemical impedance spectroscopy and I–V characterization. The XRD studies reveal well crystalline nature of the samples. The anatase phase is confirmed for undoped TiO2 and mixed phase is observed for Ni-doped TiO2. The crystallite size calculated using Scherrer formula is found to increases for 0.1 and 0.3 M Ni metal ions doped into TiO2 lattice, beyond 0.3 M concentration it tends to decrease. The Raman peaks show the shift towards lower wave number upto 0.3 M Ni concentration, beyond this it tends to shift to higher wavenumber. Absorption spectra show the redshift for Ni doped TiO2 and the obtained optical bandgap for undoped and Ni doped TiO2 (Ni\u2009=\u20090.1, 0.3, 0.5 M) are 3.08, 2.53, 2.26, and 2.39 eV respectively. From the FESEM analysis the spherical shape morphology is observed and the element composition of Ti, O, Ni are confirmed by the EDX analysis. The specific surface area and pore size are calculated using BET analysis. The XPS is used to analyze the chemical environment and it confirms the successful Ni ions insertion into TiO2 lattice sites. The charge transfer resistance, shunt resistance and electron life time are calculated from electrochemical impedance study, which shows that the charge recombination can be reduced through Ni dopant. The obtained results show an interesting feature for Ni metal ions concentration beyond 0.3 M in TiO2 nanostructure. From XRD, Raman and UV–Vis results, there seems to be a threshold for the concentration 0.3 M of Ni in TiO2. Enhanced photocurrent conversion efficiency is obtained for 0.3 M Ni doped TiO2 photoanode-based DSSC.