Anthocyanin-sensitized Cu-doped TiO2 nanoparticles for efficient and sustainable DSSCs

The growing demand for efficient and sustainable energy solutions has driven significant interest in dye-sensitized solar cells (DSSCs) utilizing natural dyes. However, enhancing their performance and long-term stability remains a major challenge. This study aims to address this gap by synthesizing Cu-doped TiO₂ nanoparticles (NPs) and investigating their application as photoanodes in DSSCs to improve energy conversion efficiency. Using a cost-effective and facile co-precipitation method, Cu-doped TiO₂ photoanodes were prepared with varying Cu concentrations (0.025 M, 0.05 M, 0.075 M, and 0.1 M) and tested with anthocyanin dye extracted from rose petals. The performance of pure and Cu-doped photoanodes in a DSSC configuration was evaluated using various physical, optical and electrical tools. The photovoltaic and charge transport characteristics were assessed using current density–voltage (J–V) measurements, incident photon-to-electron conversion efficiency (IPCE), and electrochemical impedance spectroscopy (EIS). Among the tested samples, the 0.075 M Cu-doped TiO₂ photoanode exhibited superior performance, outperforming both pristine TiO₂ and other doping concentrations. When integrated with anthocyanin dye, the DSSC featuring 0.075 M Cu-doped TiO₂ demonstrated a notable enhancement in photocurrent density, increasing from 5.8 to 7.6 mA cm⁻², while the power conversion efficiency (PCE) improved from 1.53% to 2.61%. This enhancement is attributed to the improved light-harvesting capability of Cu-doped TiO₂, along with reduced electron transport resistance and increased recombination resistance, as confirmed by EIS analysis. These findings highlight the potential of Cu-doped TiO₂ photoanodes as an effective alternative to pure TiO₂ nanostructures for advanced photovoltaic applications. Beyond DSSCs, these enhanced photoanodes hold promise for broader applications, including photocatalysis for wastewater treatment and photo-sensing technologies, further expanding their role in sustainable energy and environmental solutions.