Performance enhanced by Al doping ZnO films of CdS quantum dot sensitized solar cells

This study focuses on advancing solar cell technology using Zinc Oxide (ZnO) as a photoanodic material, known for its wide band gap, low cost, abundance, non-toxicity, and stability. Electrochemical deposition is employed for cost-effective ZnO film formation on Fluorine-doped Tin Oxide (FTO) glass plates, with acetate to enhance film smoothness. To address limited light absorption of ZnO, CdS quantum dots (QDs) were utilized to sensitize ZnO films, improving photon absorption. Aluminium (Al) doping significantly enhanced ZnO film conductivity, increasing current density in solar cells. The comprehensive characterization includes cyclic voltammetry determining reduction potentials, SEM imaging for morphological analysis, and efficiency assessment via CdS sensitization. Solar cells with Al-doped ZnO (AZO) films exhibited a remarkable efficiency increase of over 50%, attributed to enhanced conductivity and recombination resistance of the films, revealed by EIS measurements. VOC increment may result from crack-free, smooth ZnO films. UV-visible spectroscopy confirmed a widened bandgap in AZO films. The Bode phase plots of AZO films showed an increment in electron lifetime further justifying the JSC increment. This study offers valuable insights into the synergistic effects of ZnO, CdS QDs, and Al doping, thus optimizing solar cell efficiency and advancing sustainable energy technologies.