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Microstructural and Nanostructural Evolution of Light Harvester Perovskite Thin Film under the Influence of Ultrasonic Vibrations

Year: 2020

Journal: ACS Omega, Volume 5, JAN 14, page 808–821

Authors: Ahmadian-Yazdi, Mohammad-Reza; Barratt, Claire; Rahimzadeh, Amin; Eslamian, Morteza

Organizations: Shanghai Municipal Education Commission via the Oriental Scholar fundShanghai Municipal Education Commission (SHMEC); National Natural Science Foundation of China (NSFC)National Natural Science Foundation of China (NSFC)

A key step I of inexpensive and scalable perovskite thin-film formation is defect-free fabrication through low-cost and facile post-treatment processes. Methods using high annealing temperatures are not favorable for the scale-up of solution-processed thin-film solar cells, particularly on plastic/flexible substrates. This contribution analyzes the effect of ultrasonic vibrations a recently developed low-cost post-treatment process, on thin-film quality. Ultrasonic vibrations were applied to as-spun CH3NH3PbI3 perovskite thin films prepared with various solvents and antisolvents deposited on substrates with compact and mesoporous textures. Then, mechanisms of solvent evaporation,nucleation, an crystallization of perovskite grains were characterized during ultrasonic vibration. These studies demonstrate that ultrasonic vibration at low temperature facilitates heterogeneous crystallization of perovskite grains with a higher conversion of nuclei into crystal, compared with the conventional annealing process. Topographic scanning electron microscopy images confirm the dense and fully covered thin films after the evaporation of solvent. Furthermore, it is shown that crystal orientation does not change with the choice of solvent, eliminating the effect of solvent on the deposition of thin-film perovskites with this method. Therefore, this ultrasonic vibration post-treatment method is applicable to any solution-processed material and deposition technique, and it can be used to fabricate a range of thin-film devices and printed electronics.