Alcohol Assisted Solution-Combustion Technique for the Synthesis of Phase-Pure BaSnO3 Nanoparticles at 130 °C

Lowering the synthesis temperature to obtain phase pure BaSnO3, which is the host material for high figure-of-merit (FOM) perovskite transparent conductors (TCs), can expand the horizons for its optoelectronic applications, with an obvious reduction in the thermal budget. In this work, we have developed a novel solution combustion technique for the synthesis of BaSnO3 nanoparticles. A peroxo/superoxo precursor to the nanoparticles is first synthesized by co-precipitation of the tin and barium salts via the H2O2 assisted or the `CSMC' route. The phase evolution, under different drying conditions of the wet precursor to crystalline BaSnO3 nanoparticles is then studied. We find that the crystallization temperature of BaSnO3 is significantly reduced by adding an organic solvent such as ethanol or propanol to the precursor; temperatures as low as 130 °C yield phase pure BaSnO3 nanoparticles. We establish that the organic solvent increases the reactive O2 ligand content, which plays a pivotal role in the synthesis. Due to this, an exothermic reaction occurs around 130 °C, thereby providing the heat of reaction for conversion of the precursor to phase-pure BaSnO3. Importantly, this method should also allow for the facile incorporation of dopants, paving the way for synthesis of high FOM TCs at low temperatures. Such low synthesis temperatures enable BaSnO3 to be used in devices having temperature limitations during device processing, such as heterojunction Si solar cells or perovskite-based solar cells in an n-i-p architecture.