Seunghyeon Jeon

Organic gas sensors are highly promising owing to their low-temperature solution processability and low-cost scalability, yet they often suffer from inherently limited sensitivity. Conventional strategies to overcome this typically rely on introducing tailored functional materials to enhance analyte affinity or creating porous architectures to facilitate gas diffusion. However, implementing these strategies individually often necessitates complex chemical synthesis or complicated lithographic patterning. To integrate both capabilities without such complexities, we demonstrate a straightforward polymer-blending strategy using a poly(3-hexylthiophene)/poly(vinyl alcohol) (P3HT/PVA) active layer. Driven by the pronounced surface-energy contrast between P3HT and PVA, the as-cast blend film forms a vertically phase-separated architecture consisting of a P3HT-rich upper surface region and a PVA-rich lower region. Hydroxyl (–OH) groups of PVA contribute to enhanced gas–polymer interactions. A facile aqueous treatment then selectively etches the PVA phase, transforming the flat active layer into a highly accessible porous network. Driven by the synergy of the expanded physical interface and hydroxyl affinity sites, the resulting porous films exhibit faster sensing kinetics and higher sensitivity than their as-cast counterparts, with the optimized porous film (P3HT:PVA, 40:60) yielding a calculated limit of detection of 0.0086 ppm for NO₂. This study establishes a rational design principle that can maximize gas–polymer interactions without sophisticated fabrication processes.

Organic electronic materials have attracted significant attention in the development of next-generation electronic devices due to their intrinsic advantages, such as flexibility, transparency, and compatibility with large-area solution processing. Unlike their inorganic counterparts, organic electronic materials enable the fine-tuning of electrical, physical, and solubility properties through molecular design without the need for complex fabrication processes. However, challenges concerning relatively poor performance compared to conventional inorganic electronics materials remain major hurdles to widespread commercialization.,In this study, we investigated the impact of side-chain engineering on the performance of organic gas sensors. We employed a series of thiophene-based polymers functionalized with various side chains, including hydrocarbon, carboxylic acid, oligoethylene glycol, and potassium carboxylate groups. Since the side chains of conjugated polymers play a critical role in determining solubility, gas sensors were fabricated via solution processing with optimized solvents. Notably, the polythiophene incorporating ionic side chains enabled eco-friendly aqueous processing and exhibited a 50-fold increase in sensing performance compared to the reference devices, which is attributed to the strong interaction between the ionized side chains and NO2 molecules. Our findings demonstrate that strategic side-chain engineering is an effective strategy to simultaneously enhance sensitivity, selectivity, and processability, providing a viable pathway for the development of sustainable, high-performance, and flexible organic gas sensors.

Conductive two-dimensional covalent organic frameworks (2D COFs) possess intrinsic π-conjugation and long-range order, yet their electrical performance in thin-film devices remains constrained by grain boundaries and amorphous regions that interrupt charge transport. Here we report a simple and scalable strategy to overcome these limitations by bridging polycrystalline COF domains with molecularly dispersed conjugated polymers (CPs). Guided by electronic alignment, geometric compatibility, and chain-length criteria, we identify COF-CP combinations that exhibit markedly enhanced conductivity when assembled into heterostructures. By demonstrating that electrical property enhancement occurs only below the CP crystallization threshold, we show that bridging CPs require short-range ordered or near-amorphous configurations to effectively span COF grains and establish continuous transport pathways. This approach is compatible with wafer-scale fabrication and enables ppb-level NO₂ sensing by coupling COF porosity with CP-mediated charge transport. Our results establish a rational polymer-bridging strategy for COF-based electronic materials and identify key design parameters for its extension to other COF-CP systems.

Organic electronic materials have attracted significant attention in the development of next-generation electronic devices due to their intrinsic advantages, such as flexibility, transparency, and compatibility with large-area solution processing. Unlike their inorganic counterparts, organic electronic materials enable the fine-tuning of electrical, physical, and solubility properties through molecular design without the need for complex fabrication processes. However, challenges concerning relatively poor performance compared to conventional inorganic electronics materials remain major hurdles to widespread commercialization.,In this study, we investigated the impact of side-chain engineering on the performance of organic gas sensors. We employed a series of thiophene-based polymers functionalized with various side chains, including hydrocarbon, carboxylic acid, oligoethylene glycol, and potassium carboxylate groups. Since the side chains of conjugated polymers play a critical role in determining solubility, gas sensors were fabricated via solution processing with optimized solvents. Notably, the polythiophene incorporating ionic side chains enabled eco-friendly aqueous processing and exhibited a 50-fold increase in sensing performance compared to the reference devices, which is attributed to the strong interaction between the ionized side chains and NO2 molecules. Our findings demonstrate that strategic side-chain engineering is an effective strategy to simultaneously enhance sensitivity, selectivity, and processability, providing a viable pathway for the development of sustainable, high-performance, and flexible organic gas sensors.

Organic electronic materials have attracted significant attention in the development of next-generation electronic devices due to their intrinsic advantages, such as flexibility, transparency, and compatibility with large-area solution processing. Unlike their inorganic counterparts, organic electronic materials enable the fine-tuning of electrical, physical, and solubility properties through molecular design without the need for complex fabrication processes. However, challenges concerning relatively poor performance compared to conventional inorganic electronics materials remain major hurdles to widespread commercialization.,In this study, we investigated the impact of side-chain engineering on the performance of organic gas sensors. We employed a series of thiophene-based polymers functionalized with various side chains, including hydrocarbon, carboxylic acid, oligoethylene glycol, and potassium carboxylate groups. Since the side chains of conjugated polymers play a critical role in determining solubility, gas sensors were fabricated via solution processing with optimized solvents. Notably, the polythiophene incorporating ionic side chains enabled eco-friendly aqueous processing and exhibited a 50-fold increase in sensing performance compared to the reference devices, which is attributed to the strong interaction between the ionized side chains and NO2 molecules. Our findings demonstrate that strategic side-chain engineering is an effective strategy to simultaneously enhance sensitivity, selectivity, and processability, providing a viable pathway for the development of sustainable, high-performance, and flexible organic gas sensors.