Green synthesis of Ni doped ZnO nanoparticles using dandelion leaf extract and its solar cell applications

Abstract

In designing sub-100nm nanoparticles (NPs), the “green synthesis” method has drawn considerable interest in recent years due to its sustainable, reliable, and eco-friendly in nature. The green synthesis method successfully eradicates the harmful and/or toxic effects usually associated with wet chemical methods. Different concentrations of Ni2+ ion doped ZnO NPs were synthesized by using dandelion leaf, an eco-friendly and green synthesis method at ∼70 °C for 0.5 h and annealed the NPs at 600 °C for 3 h to grow the crystalline nature of the NPs. The Ni2+ ion doped ZnO NPs were surface modified to enhance the dispersion ability of the NPs in aqueous solvents. NPs with surface modifications are readily dispersed in water and further surface functionalization can be performed. NPs are characterized by XRD, SEM, EDX, FTIR, and UV–Vis. XRD confirms the high crystallinity and Ni2+ ion saturation limit ∼5% in ZnO NPs with hexagonal-Wurtzite phase structure. Shifting of diffraction angle to higher angles clearly shows successful incorporation of Ni2+ ions in ZnO host. SEM images of the ZnO nanoparticles confirm the NPs are mostly spherical and sub-100nm in size. EDX results confirm the elemental composition and purity of the NPs, and no impurity peaks were detected. FTIR confirms the band at 410 cm−1 is assigned to asymmetric stretching of the Zn–O tetrahedron. A slight shift in this peak ∼10–20 cm−1 is observed by Ni2+ ion incorporation. Also, surface modified NPs show further surface vibrations, which supports high dispersibility of the NPs. The UV–Vis absorption study confirms the decrease in bandgap of NPs from 3.1 to 2.54 eV. In addition, Ni2+ doped ZnO NPs incorporated in PVA thin films and coated on polycrystalline silicon solar cells sustain strong UV–Vis absorption, supporting their use as for the enhancement of light harvesting efficiency.