PhD candidate Sunju Yoon and master’s student Jintae Park (advisor Professor Yoon‑kyung Lee) successfully developed an environmentally friendly, water‑based photopatterning process for the conductive polymer poly(3,4‑ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and published their paper in npj Flexible Electronics (IF 14.6), a journal ranked in the top 2% in the field of electrical and electronic engineering.

Conventional photolithography for semiconductor device fabrication relies on organic materials, which causes environmental issues and significant production costs. To overcome these limitations, researchers have sought purely water‑based patterning processes. However, intrinsically water‑soluble materials such as PEDOT:PSS are difficult to pattern by selective dissolution during the development step.

The research team led by Professor Yoon‑kyung Lee, including Sunju Yoon and Jintae Park, introduced an amphiphilic block copolymer into PEDOT:PSS films to enhance the composite film’s stretchability and reduce the surface hydrophilicity. This enabled selective water uptake after UV exposure.

The technique allows direct patterning of PEDOT:PSS without additional photoresist, opening opportunities for sustainable large‑scale semiconductor manufacturing.

The developed principle could serve as a solution for aqueous photopatterning of a range of hydrophilic materials beyond PEDOT:PSS, offering broad applicability in the semiconductor manufacturing industry.

In the paper, touch sensors for stretchable displays and skin‑attachable sensors were demonstrated, utilizing small resistance changes under tensile strain and transparent optical properties.

This research was conducted in collaboration with Daegu Gyeongbuk Institute of Science and Technology and Swarthmore College (USA). It was supported by the Ministry of Science and ICT and received funding from the National Research Foundation of Korea’s Young Researcher Support Program, the Research Center Program, and the 4th phase BK21 Project Division (Nano Convergence Energy Innovative Materials and Parts Talent Training Project Group, Director Seung‑hee Lee).