Investigation of power conversion efficiency of a dye-sensitized solar cell fabricated using green-synthesized zinc oxide nanoparticles as photo-anode

Abstract

Green synthesis, a biological method for nanoparticle preparation, has been suggested as a possible eco-friendly alternative to chemical and physical methods. In this study, green synthesis of zinc oxide (ZnO) nanoparticles (NPs) from Erythrina abyssinica stem bark extract calcined under different temperatures (300-700 ℃) for application as a photo-anode in dye sensitized solar cells (DSSCs) was carried out. Synthesized ZnO Nps were subjected to characterization using X-Ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Visible (UV-Vis) Spectroscopy and photo luminescence (PL) analysis. The analysis revealed that highly crystalline hexagonal ZnO NPs were formed at 700 ℃, with the nanospheres agglomeration into non-uniform distinct NPs with a band gap energy of 3.12 eV. An efficient dye sensitized solar cell (DSSC) was fabricated with synthesized ZnO Nps as photo- anode materials. The fabricated DSSC showed an open circuit voltage (Voc) of 161 mV, short circuit current density(Jsc) of 56 μAcm-2, a Fill factor of 0.265 and a power conversion efficiency (PCE) of 2.4×10-2 % under one sun illumination. The low value of efficiency can be attributed to the limited light absorption in the visible spectrum by the ruthenium N719 dye adsorbed on the biosynthesized ZnO nanoparticles, and fast electron-hole recombination rate. Further research should be focused on improving the light absorption range of Ru N719 dye adsorbed on biosynthesized ZnO nanoparticles and minimizing the charge recombination rates through doping and heterostructuring.