Theoretical and experimental investigation of a CuO and graphene embedded polyethylene oxide counter electrode for efficient DSSCs.

Dye-sensitized solar cells (DSSCs) have garnered significant attention due to their cost-effectiveness and ease of fabrication; however, the performance of counter electrodes (CEs) remains a critical factor in optimizing efficiency. In this study, we investigate the synergistic role of a polyethylene oxide (PEO)/copper oxide (CuO)/graphene (G) composite (PEO/CuO/G) as a CE for DSSCs, employing both theoretical modeling and experimental validation. DFT calculations were used for investigating PEO hybridization nanocomposites with different metal oxides, including MgO, SiO(2), TiO(2), NiO, CuO, ZnO, and ZrO(2). The electronic properties analysis revealed that CuO is the most effective metal oxide in boosting the PEO polymer matrix, with a total dipole moment (TDM) of 10.482 Debye and ∆E of 0.422 eV. G is intended to strengthen the electrical characteristics of PEO/CuO by hybridizing with the optimal metal oxide. The hybrid composite of PEO/CuO/G showed significant improvement in electronic properties, with TDM of 18.7938 Debye ∆E 0.2566 eV. Interestingly, the morphological characteristics, electrical conductivity, surface roughness, and electrochemical properties of pure PEO, CuO, G, and PEO/CuO/G composites were systematically analyzed using Scanning Electron Microscopy (SEM), surface roughness, and electrical conductivity measurements. The results demonstrated a gradual enhancement in solar cell performance, with the optimized PEO/CuO/G composite exhibiting superior electrical conductivity (12.56 S/m), high surface roughness (8.1 µm), and an interconnected conductive network, facilitating efficient charge transfer. Photovoltaic (PV) measurements revealed a systematic improvement in short-circuit current density (J(sc)) from 11.428 mA/cm(2) (PEO) to 16.916 mA/cm(2) (PEO/CuO/G) and fill factor (FF) from 63.4 to 65.1%, leading to a notable enhancement in overall efficiency from 4.33% to 6.42%. The observed improvements are attributed to the combined effects of CuO's catalytic properties and graphene's high electrical conductivity, forming a stable, efficient CE material. Theoretical modeling further supports these findings by demonstrating enhanced electron transport and reduced charge recombination within the composite structure. This study highlights the potential of PEO/CuO/G as a low-cost and high-performance CE for DSSCs, paving the way for further optimization in next-generation solar energy aerospace applications.