Low-LOD organic thin-film NO2 gas sensor based on a porous polystyrene structure

Enhancing gas diffusion and interfacial accessibility in organic semiconductor films is essential for achieving high-performance nitrogen dioxide (NO 2 ) sensing at low concentration levels. This study presents a strategy for enhancing the nitrogen dioxide (NO 2 ) sensing performance of α-hexathiophene (α-6T) and Copper (II) Phthalocyanine (CuPc) organic semiconductor films by introducing a porous polystyrene (PS) structure onto SiO 2 substrates by solution spin-coating. The influence of PS concentration on the morphology and gas-sensing response characteristics was investigated. At an optimal PS concentration of 7 mg/mL, the sensitivity of the sensors was enhanced, and the theoretical limit of detection (LOD) was reduced. The PS/CuPc sensor achieved a sensitivity of 270.96%/ppm and a theoretical LOD as low as 299 ppb. We attribute this performance enhancement to the PS structure increasing the specific surface area of the organic semiconductor film, thereby promoting the diffusion and desorption of gas molecules within the semiconductor film. This work provides a reliable preparation method and mechanistic insights for developing gas sensors with low detection limits.