Modification of the Properties of Titanium Carbide MXene by Ag Doping via Ion Implantation for Quantum Dot-Sensitized Solar Cell Applications

The current work investigates ion implantation of a transition metal (Ag) into MXene/TiO₂ films utilizing low energy at different fluence rates of 5 × 10¹², 5 × 10¹³, 5 × 10¹⁴, and 5 × 10¹⁵ ions-cm⁻² respectively. The morphology and crystal structure of the transition metal-implanted MXene/TiO₂ samples were characterized by field-emission scanning electron microscopy, x-ray diffraction, and Raman spectroscopy. In addition, x-ray photoelectron spectroscopy revealed the presence of Ag(I) oxidation state at 5 × 10¹⁴ ions-cm⁻² fluence, whereas at a higher fluence of 5 × 10¹⁵ ions-cm⁻², both Ag(I) and Ag(0) states were found. The optical properties of the transition metal-implanted MXene/TiO₂ samples were also investigated via UV-visible and photoluminescence studies. The transition metal implantation significantly enhanced the light absorption and reduced the charge recombination owing to the formation of defect states. Finally, the quantum dot-sensitized solar cell (QDSSC) device fabricated with 5 × 10¹⁴ ions-cm⁻² (Ag_3) exhibited the highest power conversion efficiency of 3.94% versus the unimplanted MXene/TiO₂-based QDSSC (2.48%), which is attributed to enhanced absorption and minimization of charge recombinations, as confirmed by photovoltaic characteristics and Nyquist plots.