Advancements in oxidative chemical vapor deposition (oCVD) with liquid oxidant: A true dry vacuum manufacturing approach for optoelectronic devices

Abstract

Conducting polymers have attracted significant interest due to their unique properties, including metal-like conductivity, ionic conductivity, optical transparency, and mechanical flexibility. Poly(3,4-ethylene-dioxythiophene):poly(styrene sulfone) (PEDOT:PSS) is commonly utilized as the hole transport layer (HTL) in optoelectronic devices. However, its high acidity, primarily attributed to the low pH of PSS, poses challenges such as counter electrode etching, detrimental interactions with the photoactive layer, and device instability. To address these issues, researchers are exploring alternative HTL materials and deposition methods. Oxidative chemical vapor deposition (oCVD) has emerged as a promising technique to fabricate high-quality PEDOT thin films without PSS, enhancing device stability. The selection of an appropriate oxidant is crucial in oCVD, as it significantly influences film properties and performance. The utilization of liquid oxidants enables direct integration of conductive polymer thin films into devices through a one-step, dry process, eliminating the need for post-deposition rinsing and ensuring compatibility with solvent-sensitive and temperature-sensitive substrates. Moreover, precise control over liquid oxidant flow rates provides advantages over solid oxidants. This prospective article provides an overview of recent advancements in engineering the texture and nanostructure of conducting polymers to boost electrical conductivity and enhance optoelectronic performance. Additionally, it provides a comprehensive overview of recent progress in oCVD method, focusing on the use of liquid oxidants. Furthermore, the prospective article underscores the significance of oCVD in the efficient fabrication of PEDOT thin films without PSS, thus playing a pivotal role in the development of stable optoelectronic devices.

Graphical Abstract