인천대학교 인디고클랫폼 인천대학교 기술지원허브

Poly(3-alkylthiophene) (P3AT) is a representative p-type organic semiconductor with a distinctive molecular structure that incorporates a π-electron system, promoting charge carrier mobility and providing exceptional electrical conductivity. The alkyl side chain linked to the π-electron backbone was found to have a significant effect on charge carrier transport and mechanical properties. This study presents a comprehensive comparison of the gas-sensing performances of various gases (NO2, SO2, and CO2) and the mechanical properties of gas sensors fabricated from P3AT with alkyl chain lengths of 6, 8, 10, and 12 (P3HT, P3OT, P3DT, and P3DDT). Our in- vestigations revealed that as the alkyl side chain length increased, the gas sensor performance significantly improved owing to the increase in free volume, concurrently promoting improved flexibility. The P3DDT sensor exhibited a sensitivity approximately twice that of the P3HT sensor, along with superior mechanical flexibility owing to its free volume.

In this study, we examined how the regioregularity of poly(3-hexylthiophene) (P3HT) affects molecular packing, free volume, charge transport, and gas sensing properties. Our results showed that the presence of regular alkyl side chains on the polymer backbone promoted a high degree of structural order in regioregular P3HT molecules, leading to a compact packing density and reduced free volume. Consequently, it was more challenging for NO2 molecules to interact with the hole charge carriers in the conductive channel. On the other hand, the regiorandom P3HT films displayed a larger free volume, attributed to the irregular side chains, which facilitated the gas−analyte interaction while impeding efficient charge transport. Thus, these films exhibited greater sensitivity to analyte gas molecules. The molecular order, packing density, and hardness of P3HT films were confirmed through the use of multiple techniques, including UV−vis spectroscopy, atomic force microscopy, and grazing-incidence X-ray diffraction. Additionally, the regiorandom P3HT films showed enhanced mechanical flexibility compared to the regioregular films. In conclusion, our findings emphasize that the regularity of polymer molecules plays a significant role in determining the charge carrier transport and gas adsorption characteristics.

Organic semiconductors (OSCs) are promising sensing materials for printed organic gas sensors. Although OSCs show promise since they are mechanically flexible, cost-effective, and lightweight, they still face challenges related to low sensitivity and poor stability under ambient conditions; their development therefore lags that of inorganic-based gas sensors. Functional nanomaterials can be incorporated into organic semiconductors to complement the gas sensitivity and stability. Herein, we describe the fabrication of novel organic–inorganic hybrid gas sensors via the blending of perovskite nanocrystals and conductive polymer. We introduced a perovskite-structured material, CsPbBr3, into a conductive polymer matrix, which substantially improved its gas- sensing performance while maintaining its high responsivity and response rates. To further improve the adsorption of target gas molecules, we modified the surface of the perovskite using a zwitterionic polymer subjected to a hydration treatment. The results demonstrate that the amide group of the encapsulation polymer exhibits high affinity toward NO2 gas molecules and that this affinity becomes more pronounced upon hydration of the polymer. We also demonstrate the perovskite materials in the semiconducting polymer layer can protect the polymer thin film against oxidation during prolonged storage under ambient conditions because of the perovskite crystals’ ability to adsorb oxidizing molecules.