Air pollutants like nitrogen dioxide (NO 2 ), primarily produced during fossil fuel combustion, pose a serious concern for human health, contributing to respiratory diseases like pulmonary edema, bronchitis, and asthma. Effective air-quality monitoring therefore requires portable gas sensors that offer high sensitivity, selectivity, and long-term stability. Among existing technologies, organic field-effect transistors (OFETs) are promising for highly sensitive portable sensors with their lightweight, flexible, and simple-to-fabricate structure.
However, a critical challenge for their practical application is the limited lifetime of organic semiconductors, which are vulnerable to degradation caused by moisture and oxygen. This leads to a gradual decline in device performance and ultimately contributes to growing electronic waste and environmental pollution.
Addressing this issue, a research team led by Professor Yeong-Don Park from the Department of Energy and Chemical Engineering at Incheon National University in South Korea has developed novel eco-friendly OFET gas sensors. These sensors utilize blended polymer films combining poly(3-hexylthiophene) (P3HT), a widely used organic semiconductor, and poly(butylene succinate) (PBS). “ Using PBS, a well-known biodegradable polymer, and effective solvent engineering, we demonstrated that high sustainability and device performance can be achieved simultaneously, ” says Prof. Park. Their study was made available online on September 24, 2025, and published in Volume 523 of the Chemical Engineering Journal on November 01, 2025.
To fabricate the sensors, the researchers prepared blended solutions of P3HT and PBS using either chloroform (CF) or a mixture of chloroform and dichlorobenzene (CF:DCB) as solvents. These blended solutions were deposited onto silicon substrates and fitted with gold electrodes to form OFET-based gas sensors. This yielded two distinct sensor types.
The choice of solvent played a crucial role in determining the internal structure of the active polymer layer and, consequently, the device performance. Specifically, CF-processed films exhibited a horizontal phase separation of P3HT and PBS, producing an uneven surface structure. In contrast, the CF:DCB-processed films demonstrated a uniform surface structure across all compositions owing to vertical phase separation. Although the electrical performance of both sensors decreased with increasing PBS content, the sensor with the CF-processed film stopped functioning when PBS content exceeded 50%. In contrast, the CF:DCB-processed sensor retained a stable performance even with up to 90% PBS content.
Beyond electrical stability, the researchers also evaluated the devices' gas-sensing capabilities. These tests revealed that the sensitivity of both devices to nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon dioxide (CO₂) increased with higher PBS content. Notably, the CF-processed films demonstrated higher sensitivity, while the CF:DCB-processed films displayed excellent, stable sensitivity even with 90% PBS content. The devices also showed significantly higher sensitivity for NO 2 over SO 2 and CO 2 . Increasing PBS content enhanced flexibility of the films and both devices were found to be biodegradable in seawater.
“ Our eco-friendly and resource-efficient sensors open up new possibilities for environmentally sustainable gas sensing technologies suitable for large-scale or disposable applications , ” concludes Prof. Park. “ In the long term, biodegradable organic sensors could significantly reduce electronic waste, especially for sensors deployed in natural or marine environments. ”
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About Incheon National University
Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.
Website: https://www.inu.ac.kr/sites/inuengl/index.do?epTicket=LOG
About the author
Yeong-Don Park serves as a Professor in the Department of Energy and Chemical Engineering at Incheon National University, where he is also the director of the Organic Optoelectronics Laboratory. His research is dedicated to advancing organic gas sensors, specifically by improving device performance via materials engineering, structural optimization, and surface modification. By integrating conductive polymers with functional nanomaterials, such as zeolites, porous carbon, and biodegradable polymers, his team develops sensors characterized by high sensitivity and selectivity. He earned his PhD in Chemical Engineering from the Pohang University of Science and Technology and completed his postdoctoral fellowship at the University of California, Santa Barbara.
Chemical Engineering Journal
Experimental study
Not applicable
Solvent-driven phase separation strategy for eco-friendly high-performance organic gas sensors
1-Nov-2025
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.