, /PRNewswire/ – Organic field-effect transistors are promising for highly sensitive portable gas sensors, but their practical application is limited by the atmospheric instability of organic semiconductors. This instability eventually leads to reduced device performance, contributing to growing electronic waste. To address this issue, researchers, through careful solvent engineering, have now developed a new class of eco-friendly, high-performance, and durable organic gas sensors using biodegradable polymers.

The proposed gas sensors demonstrate how solvent engineering leverages biodegradable polymers to achieve both high sustainability and device performance, ushering in a new paradigm for eco-friendly resource-efficient gas sensors.

Air pollutants like nitrogen dioxide (NO2), 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 NO2 over SO2 and CO2. 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."

Reference

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SOURCE Incheon National University