A comprehensive design schedule for electrosprayed thin films with different surface morphologies

Abstract

Electrospraying is a technique in which a liquid jet breaks up into droplets under the influence of electrical forces. The technique is outstanding because of its high deposition efficiency and ability to achieve thin films with different surface morphologies. Nowadays, it is applied in the deposition of thin films for nanoelectronics in lithium-ion (Li-ion) batteries, fuel cells, and solar cells, where the performance of the deposited layers is determined by their morphologies. Although important in the design of thin films, a systematic way of depositing thin films with the desired surface morphologies for optimal operation is not available. In this study, a literature survey has been conducted from which key electrospray parameters have been identified and a comprehensive design schedule for thin films with different surface morphologies has been developed. The developed design schedule specifically targets inorganic salts, as the surface morphology of organic salts, particularly polymers, is subject to diverse factors such as solvent interaction and crystallization behavior. To verify the developed schedule, different thin films have been deposited on aluminum foil substrates using lithium salt precursor solutions by altering key electrospray parameters. Surface morphologies of the thin films have been characterized using scanning electron microscopy. Results show three distinct surface morphologies, porous with agglomerates, porous reticular, and dense particulate morphologies, and they agree with the predictions of the developed design schedule.