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Organometallic halide perovskite (MAPPbBr 3 ), Rust-based Vapor Phase Polymerization (RVPP)-PEDOT hole transporting layers and (RVPP-PEDOT)/MAPPbBr 3 dual-layer, deposited on fluorine doped tin oxide glass were studied at room temperature using steady-state absorption, time-resolved photoluminescence imaging and femtosecond time-resolved absorption spectroscopy. Application of these techniques in conjunction with diverse excitation intensities allowed determination of various optoelectronic properties of the perovskite film and the time constant of the hole extraction process. Spectral reconstruction of the bandedge absorption spectrum using Elliot's formula enabled separation of the exciton band. The binding energy of the exciton was determined to be 19 meV and the bandgap energy of the perovskite film was 2.37 eV. Subsequent time-resolved photoluminescence studies of the perovskite film performed using a very weak excitation intensity followed by a global analysis of the data revealed monomolecular recombination dynamics of charge carriers occurring with an amplitude weighted lifetime of 3.2 ns. Femtosecond time-resolved transient absorption of the film performed after excitation intensity spanning a range of over two orders of magnitude enabled determining the rate constant of bimolecular recombination and was found to be 2.6 × 10 −10 cm 3 s −1 . Application of numerous high intensity excitations enabled observation of band filling effect and application of the Burstein–Moss model allowed to determine the reduced effective mass of photoexcited electron–hole pair in MAPPbBr 3 film to be 0.19 rest mass of the electron. Finally, application of transient absorption on RVPP-PEDOT/MAPPbBr 3 enabled determination of a 0.4 ps time constant for the MAPPbBr 3 -to-PEDOT hole extraction process. 

This study presents a comprehensive investigation on the aerosol synthesis of a semiconducting double perovskite oxide with a nominal composition of KBaTeBiO 6 , which is considered as a potential candidate for CO 2 photoreduction. We demonstrate the rapid synthesis of the multispecies compounds KBaTeBiO 6 with extreme high purity and controllable size through a single-step furnace aerosol reactor (FuAR) process. The formation mechanism of the perovskite in the aerosol route is investigated using thermogravimetric analysis to identify the optimal reference temperature, residence time and other operational parameters in the FuAR synthesis process to obtain the highly pure KBaTeBiO 6 nanoparticles. It is observed that particle formation in the FuAR is based on a mixture of gas-to-particle and liquid-to-particle mechanisms. The phase purity of the perovskite nanoparticles depends on the ratio of the residence time and the reaction time. The particle size is strongly affected by the precursor concentration, residence time and the furnace temperature. Finally, the photocatalytic performance of the synthesized KBaTeBiO 6 nanoparticles is investigated for CO 2 photoreduction under UV-light. The best performing sample exhibits an average CO production rate of 180 μmol g −1 h −1 in the first half hour with a quantum efficiency of 1.19%, demonstrating KBaTeBiO 6 as a promising photocatalyst for CO 2 photoreduction.