Synthesis and Characterization of Monodispersed β‑Ga₂O₃ Nanospheres via Morphology Controlled Ga₄(OH)₁₀SO₄ Precursors

To our best knowledge, monodispersed β-Ga₂O₃ nanospheres were successfully synthesized for first time via morphology-controlled gallium precursors using the forced hydrolysis method, followed by thermal calcination processes. The morphology and particle sizes of the gallium precursors were strongly dependent on the varying (<i>R</i> = SO₄^2–/NO₃^–) concentration ratios. As <i>R</i> decreased, the size of the prepared gallium precursors decreased and morphology was altered from sphere to rod. The synthesized S2 (<i>R</i> = 0.33) consists of uniform and monodispersed amorphous nanospheres with diameters of about 200 nm. The monodispersed β-Ga₂O₃ nanospheres were synthesized using thermal calcination processes at various temperatures ranging from 500 to 1000 °C. Monodispersed β-Ga₂O₃ nanospheres (200 nm) consist of small particles of approximately 10–20 nm with rough surface at 1000 °C for 1 h. The UV (375 nm) and broad blue (400–450 nm) emission indicate recombination via a self-trapped exciton and the defect band emission. Our approach described here is to show the exploration of β-Ga₂O₃ nanospheres as an automatic dispersion, three-dimensional support for fabrication of hierarchical materials, which is potentially important for a broad range of optoelectronic applications

Reduced Graphene Oxide/Mesoporous TiO₂ Nanocomposite Based Perovskite Solar Cells

We report on reduced graphene oxide (rGO)/mesoporous (mp)-TiO₂ nanocomposite based mesostructured perovskite solar cells that show an improved electron transport property owing to the reduced interfacial resistance. The amount of rGO added to the TiO₂ nanoparticles electron transport layer was optimized, and their impacts on film resistivity, electron diffusion, recombination time, and photovoltaic performance were investigated. The rGO/mp-TiO₂ nanocomposite film reduces interfacial resistance when compared to the mp-TiO₂ film, and hence, it improves charge collection efficiency. This effect significantly increases the short circuit current density and open circuit voltage. The rGO/mp-TiO₂ nanocomposite film with an optimal rGO content of 0.4 vol % shows 18% higher photon conversion efficiency compared with the TiO₂ nanoparticles based perovskite solar cells