Synergistic effect of pulsed laser synthesized ternary TiO₂/graphitic carbon nitride/CdSe nanocomposite photoanode for high-performance N719 dye co-sensitized solar cells

In this work, we have fabricated dye-sensitized solar cells (DSSCs) employing a TiO₂/GCN binary nanocomposite (b-NCs) and TiO₂/GCN/CdSe ternary nanocomposite (t-NCs) as photoanode materials. These nanocomposites were synthesized by combining TiO₂ Nanoparticles (NPs), graphitic carbon nitride (GCN) sheets, and CdSe in various mass ratios using a straightforward novel pulsed laser ablation in liquid technique. The PLAL technique uses a high-energy pulsed laser to create a plasma plume in a liquid medium, generating cavitation bubbles that burst, producing ultrasonic shockwaves. These shockwaves are essential for breaking apart nanoparticles to create highly pure b-NCs and t-NCs. The structural, morphological, compositional, and optical properties of the synthesized NCs were examined using a variety of techniques, including XRD, FTIR, SEM, TEM, XPS, DRS, and PL. The band gap energies were calculated using the Kubelka-Munk function and were determined to be 3.23, 2.91, 3.12, and 2.56 eV for TiO₂, GCN, TiO₂/GCN b-NCs, and TiO₂/GCN/CdSe t-NCs, respectively. DSSCs were fabricated using a photoanode of TiO₂, TiO₂/GCN b-NCs, and TiO₂/GCN /CdSe t-NCs film with N719 dye. The GCN sheets bonded to the TiO₂ surface increase electron transport, thus restraining the recombination of photogenerated electrons from TiO₂ and electrolytes, leading to better device performance. It was found that the fabricated DSSC devices with TiO₂/GCN/CdSe t-NCs demonstrate a current density (Jsc) of 20.56 mA/cm², power conversion efficiency (PCE) of 8.04 %, with a high open-circuit voltage of 0.69 V under one sun illumination, in contrast to the TiO₂ and TiO₂/GCN b-NCs photoanode-based DSSCs, which exhibited relatively lower PCEs of 5.56 % and 7.08 %, respectively. The synergistic effect of N719 dye and CdSe significantly improves charge separation, leading to high current density and PCE for the devices fabricated with TiO₂/GCN/CdSe t-NCs photoanode.