Ultrasonic-Assisted Spin-Coating: Improved Junction by Enhanced Permeation of a Coating Material within Nanostructures

Abstract

Over the last decades, the spin-coating (SC) technique has been widely used to prepare thin films of various materials in the liquid phase on arbitrary substrates. The technique simply relies on the centrifugal force to spread a coating solution radially outward over the substrate. This mechanism works fairly well for solutions with low surface tension to form thin films of reasonable junctions on smooth substrates. Here, we present a modified SC technique, namely, ultrasonic-assisted spin-coating (UASC), to form thin films of coating solution having high surface tension on rough substrates with excellent junctions. The UASC technique couples SC with an external ultrasonic wave generator to provide external perturbation to locally break down big drops of the coating material into smaller droplets via Rayleigh instability. Because of their lower mass, these tiny droplets gain low momenta and move slowly both in radial and azimuthal directions, giving them an enough time to effectively permeate within pores, thereby yielding excellent junctions. Furthermore, we also investigated the effect of junction improvement on conventional and inverted bulk heterojunction organic solar cells. Intriguingly, the organic solar cells fabricated by the UASC method showed an improved efficiency compared to typical SC owing to efficient charge transfer across the junction. These results clearly imply that UASC is a simple and powerful technique which can significantly enhance the device performance by improving the junction. Moreover, we believe that UASC can be more effective for the preparation of devices composed of multilayers of different materials having complicated nanostructures.

Molecular design and architectonics towards film-based fluorescent sensing

“…Kim et al developed an ultrasonic-assistant spin/blade-coating method, which can be used to prepare thin films on rough substrates with coating solutions of high surface tension. 164 The ultrasonication can provide external perturbation to break down big droplets into smaller droplets, enabling coating solutions to permeate within the pores of the rough substrates.…”

Centrifugal Force-Assisted Preparation of Closely Packed Transition Metal Dichalcogenide Nanoscrolls for Enhanced Optoelectronic Performance

“…When the droplet is deposited on a rotated substrate, the centrifugal force drives the fluid flow outward the substrate surface. 37,38 Inspired by rolling up the TMDC nanosheet with the aid of volatile organic solvent evaporation-induced fluid flow, we were curious to investigate the effect of fluid flow controlled by a centrifugal force during spin-coating on the formation of a TMDC nanoscroll. In this study, we present a method for efficiently fabricating closely packed TMDC nanoscrolls assisted by a centrifugal force during spin-coating liquid polyethylene glycol (PEG).…”

“…Spin-coating is widely used to uniformly spread liquid droplets onto a substrate. When the droplet is deposited on a rotated substrate, the centrifugal force drives the fluid flow outward the substrate surface. , Inspired by rolling up the TMDC nanosheet with the aid of volatile organic solvent evaporation-induced fluid flow, we were curious to investigate the effect of fluid flow controlled by a centrifugal force during spin-coating on the formation of a TMDC nanoscroll.…”