Development of Sensitive, High-Performance Organic Gas Sensors via Dimensionally Controlled Perovskites

Organic semiconductors are considered promising alternatives to rigid inorganic materials for next-generation smart gas sensors. However, their intrinsic limitations such as low surface reactivity, insufficient charge density, and small surface area hinder their performance. To address these challenges, we engineer composite sensing layers by incorporating perovskite nanocrystals into poly(3-hexylthiophene) (P3HT) thin films and systematically analyze how perovskite structure and defect formation modulate the electronic and chemical properties of the hybrid films. The semiconducting nature of perovskites and their favorable band alignment with P3HT enhance charge transport in organic field-effect transistors (OFETs) without compromising charge transfer efficiency, which is difficult to achieve using conventional non-conductive inorganic porous materials. Perovskite quantum dots exhibit uniform dispersion and improved percolation pathways, resulting in the significant enhancement of OFET performance. In contrast, perovskite nanowires show higher crystallinity and abundant Br-vacancies, partially accompanied by Cs₄PbBr₆-domains, which serve as highly reactive adsorption sites for electron-withdrawing gas molecules. Consequently, NW-30 wt.% blended devices demonstrate the highest responsivity toward NO₂ gas, achieving a sensitivity of 3.05%/ppm and a limit of detection of 0.0055 ppm. This work demonstrates the potential of dimensionally controlled perovskites with halide-vacancy engineering as a versatile strategy for designing high-performance, room-temperature, and flexible organic gas sensors.