This technology utilizes a two-phase dip-coating composition consisting of a water bottom layer and a top layer of poly(3-hexylthiophene) (P3HT) dissolved in chloroform, with a chlorobenzene solvent additive floated on top. A substrate is immersed in and then withdrawn from this solution to form a semiconductor polymer thin film.
While dip-coating is advantageous for obtaining uniform organic semiconductor films, it has historically been difficult to scale for mass production due to the large volume of polymer solution required to fill the reservoir. Two-phase dip-coating requires a solvent pair that forms a stable interface; however, most solvents that dissolve π-conjugated polymers have a high density of 1.1 g/cm³ or greater, making it difficult to find a suitable bottom support solvent. Additionally, reducing the use of environmentally toxic halogenated solvents remains a challenge.
This technology uses reusable water as a bottom support layer, significantly reducing the amount of polymer solution required. It promotes polymer crystallization using a solvent with a boiling point of 50–200°C and a chlorobenzene additive that slows evaporation. The result is a thin film with a uniform surface, improved molecular alignment, higher crystallinity, and enhanced charge mobility. Applicable to organic field-effect transistors, flexible/wearable electronics, and large-area organic sensor manufacturing, this method enables mass production of high-performance organic semiconductor thin films using only a small amount of polymer solution.
This invention was developed with support from the Ministry of Education for the development of high-performance gas sensors based on phase-separated MOF/conjugated polymer hybrid thin films.
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