Title : The role of water in the synthesis of AlOx thin films by atmospheric-pressure mist chemical vapor deposition and effects on junction properties at the AlOx/Si interface
The role of an additional solvent thiosemicarbazide (TSC) in the synthesis of a highly crystallized inorganic-organic halide FA0.8Cs0.2PbIxBr3-x perovskite using the co-solvent N, N-dimethylformamide (DMF)/1-Cyclohexyl-2- pyrrolidone (CHP) has been investigated. Ellipsometry combined with XRD and FTIR spectroscopy was used for characterization purposes. The average crystal grain size increased from several hundred nanometers to 1.5 μm with increasing content of TSC in the co-solvent. Ellipsometry and FTIR spectroscopy revealed that the as-deposited perovskite film before thermal annealing was distorted and featured a large number of voids; also, the Pb ions formed complexes with the C=S groups in TSC, which suppressed the excessive nucleation. Removal of the co-solvent at the thermal annealing stage facilitated the rearrangement of the [Pb(IxBr3-x)6] 4- octahedral structure from a zero-dimensional to a three-dimensional network, which enhanced crystal grain growth.