Synthesis of nanostructured zinc oxide and its composite with carbon dots for DSSCs applications using flexible electrode

ZnO nanowires (ZnO NWs), ZnO nanoparticles (ZnO NPs) and carbon dots (C-dots) were synthesized by hydrothermal, sol-gel and hydrothermal methods respectively. They were also characterized and applied for dye sensitized solar cells (DSSCs). The effects of C-dots on ZnO NWs and ZnO NPs have been evaluated. The C-dots were used at a mole ratio of citric acid (CA) to ethylene diamine (EDA) of 1 : 1.5. These C-dots were found to enhance the performance of the flexible electrode DSSCs. After the addition of C-dots, the power conversion efficiency (PCE) of ZnO NPs was boosted to be two times higher than that of ZnO NPs DSSCs without C-dots. Similarly, the ultraviolet (UV)-band revealed a blue shift, resulting in a lower band gap and a reduced charge transfer resistance, which can enhance the PCE of DSSCs. The loaded quantity on the flexible electrode substrate made of polyethylene terephthalate (PET) was optimized (50 mg). For DSSCs, the PET flexible electrode conductive polymer has produced positive outcomes. For ZnO NWs and ZnO NWs@C-dots, the PCE values were 1.45% and 4.25%; while for ZnO NPs and ZnO NPs@C-dots, they were 2.34% and 5.81%, respectively. This work achieved remarkable and competitive performance when compared to solid (indium tin oxides/glass)-based substrate.