Effect of doping on the phase stability and photophysical properties of CsPbI2Br perovskite thin films.

In this study, we demonstrate that the crystallization process of CsPbI2Br films can be modulated when small amounts of additives are added to the precursor solution, leading to the formation of the bright brownish α-phase perovskite films with high orientation along the [100] crystallographic direction. Doped CsPbI2Br films exhibit improved crystallinity, with high coverage, large grain size and pinhole-free surface morphology, suitable for making high performance optoelectronic devices. We also explored the role of Cl in the photophysical properties of CsPbI2Br perovskite films using the temperature dependent photoluminescence technique. We found that the Cl ions enhance the photoluminescence emission by reducing the density of trap states, and also decrease the exciton binding energy from (22 ± 3) meV to (11 ± 2) meV. We believe this work contributes to understanding the effect of doping on the crystallization process with an in-depth insight into the photophysical properties of the cesium-based perovskite materials.

Highly efficient nanostructured CoFe2 O4 thin film electrodes for electrochemical degradation of rhodamine B.

In this work, we report the application of highly efficient electrodeposited cobalt ferrite (CoFe2 O4 ) thin films in electrochemical degradation of rhodamine B. XRD, FTIR and Raman spectroscopic studies confirmed the formation of single phase CoFe2 O4 . SEM analysis revealed a very fine nanorods dispersed uniformly with average size around 30 nm. UV-Vis spectrophotometry emphasized that the optical band gap value is 1.6 eV. Moreover, the elaborated CoFe2 O4 thin films showed a good efficiency for the electrochemical degradation of an aqueous solution of rhodamine B (RhB) attaining 99% during the first 3 min of reaction time. The trapping experiments revealed that the hydroxyl radicals were the main active species leading to the removal of RhB initial concentration of 10 mg/L in a very short time. PRACTITIONER POINTS: A simple electrodeposition technique was used to fabricate CoFe2 O4 thin. XRD and FTIR studies revealed the formation of pure cubic spinel phase. Nano-rod like morphology has been successfully synthesized. The rhodamine B aqueous solution has been completely decolorized using the obtained CoFe2 O4 thin films.