Synthesis of BaTiO₃ and SrTiO₃ nanoparticles: Effect of annealing temperatures on their morphological, crystalline, optical and photovoltaic properties

In this study, highly crystalline BaTiO₃ and SrTiO₃ nanoparticles were synthesized via bi-modal distribution method followed by annealing at different temperatures and time. The impacts of annealing temperatures on the nanoparticles were investigated by their various chemical, crystalline, structural, surface and photovoltaic properties. An increase in particle sizes of both BaTiO₃ and SrTiO₃ from 43-77 nm was observed with increase in annealing temperatures due to the agglomeration of the nanoparticles. Raman scattering spectroscopy, X-ray diffraction (XRD), and Transmission electron microscopic (TEM) results revealed that polycrystalline cubic and tetragonal nanoparticles were formed. It was also found that the optical band gap of BaTiO₃ and SrTiO₃ considerably decreased from 3.86 to 3.47 eV for BaTiO₃ and 3.71 to 3.27 eV for SrTiO₃ as annealing temperatures increased from 600-900 �C. The fabricated dye sensitized solar cells (DSSCs) with SrTiO₃ photo anode achieved moderately good power conversion efficiency of 2.72% which was much higher than the power conversion efficiency of the DSSCs with BaTiO₃ photo anode (0.15%).