Optimization of TiO₂ Electrodes via TiCl₄ Concentration Tuning for Enhanced Dye–Sensitized Solar Cell Performance

Titanium dioxide (TiO₂) nanostructured electrodes were synthesized using a simple and cost-effective chemical bath deposition (CBD) method by varying the concentration of titanium tetrachloride (TiCl₄). The structural and morphological properties of the deposited TiO₂ films were systematically characterized using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). XRD analysis confirmed the formation of a monoclinic rutile phase of TiO₂ (JCPDS Card No. 46-1238), while FE-SEM images revealed distinct morphological variations—ranging from compact structures to nanorice and flower-like architectures—depending on the TiCl₄ concentration. Energy-dispersive X-ray spectroscopy (EDX) confirmed the stoichiometric composition of TiO₂, with Ti and O present in a near-ideal atomic ratio. Optical absorption studies using UV-Vis spectroscopy demonstrated enhanced light absorption after sensitization with N719 dye, particularly in the visible region (λ ≈ 550 nm). The photoelectrochemical performance of dye-sensitized solar cells (DSSCs) fabricated with these TiO₂ electrodes was evaluated under simulated AM 1.5G illumination (100 mW/cm²). The optimal TiCl₄ concentration (0.15 M) yielded a power conversion efficiency (PCE) of 1.62%, with an open-circuit voltage (Voc) of 0.75 V, short-circuit current density (Jsc) of 4.14 mA/cm², and fill factor (FF) of 0.52. Electrochemical impedance spectroscopy (EIS) and incident photon-to-electron conversion efficiency (IPCE) measurements further validated the improved charge transport and photon absorption characteristics. This study highlights the critical role of TiCl₄ concentration in tailoring TiO₂ nanostructures for efficient DSSC applications, providing insights into morphology-dependent photovoltaic performance.