An Ion‐In‐Conjugation‐Boosted Organic Semiconductor Gas Sensor Operating at High Temperature and Immune to Moisture

Abstract

Organic electrical gas sensors have been developed for many decades because of their high sensitivity and selectivity. However, their industrialization is severely hindered by their intrinsic humidity susceptibility and poor recovery. Conventional organic sensory materials can only operate at room temperature owing to their weak intermolecular interactions. Herein, we demonstrate using a croconate polymer (poly-4,4'-biphenylcroconate) that the "ion-in-conjugation" concept enables organic gas sensors to operate at 100 8C and 70 % relative humidity with almost complete recovery. The fabricated sensor had a parts-per-billion (ppb) detection limit for NO 2 and showed the highest sensitivity (2526 ppm À1 at 40 ppb) of all reported NO 2 chemiresistive sensors. Furthermore, charge transfer increased with temperature. Theoretical calculations and in situ FTIR spectra confirmed the ion-inconjugation-inspired hydrogen bond as key for excellent sensitivity. A NO 2 alarm system was assembled to demonstrate the feasibility of this sensor.

Recent Advances in Smart Organic Sensors for Environmental Monitoring Systems

“…This slow desorption results in poor gas sensor recovery and high cycle-to-cycle variations. To enhance the stability and recovery of organic gas sensors, Yu et al introduced an ion-in-conjugation material as an active layer of the gas sensor; they constructed organic gas sensors that can operate at 100 °C and 70% relative humidity with a highly recovered state . In that study, poly-4,4′-biphenylcroconate (PBPC) polymer, an ion-in-conjugation material, was used as an active layer of the NO 2 gas sensor.…”

Surface adhesion engineering for robust organic semiconductor devices

“…Organic semiconductors, as a class of electronic materials that feature semiconducting properties and can be used to fabricate semiconductor devices and integrated circuits, have become a research hotspot in the new century. 1–6 Compared with inorganic semiconductors, organic semiconductors, including small molecules, 7,8 polymers, 9–11 and small-molecule:polymer blends, 12,13 have obvious advantages in terms of low cost, ease of dissolving, light weight, and low-temperature processing, and have been extensively used in organic solar cells, 14–17 organic thermoelectric devices, 18–20 organic field-effect transistors, 21–24 organic light-emitting diodes, 25–28 organic sensors 29–32 and so on. More importantly, the solubility, polarity, and electrical properties of organic semiconductors can be feasibly adjusted by tailoring molecular interactions and structures, providing the necessary means to enrich the diversity of materials.…”

Moisture-Insensitive and Highly Selective Detection of NO2 by Ion-in-Conjugation Covalent Organic Frameworks

“…With the rapid development of industrialization and urbanization, the combustion of fossil fuels generates large amounts of nitrogen dioxide (NO 2 ), which seriously threatens the environment and human beings. , NO 2 is the main factor for the formation of photochemical smog and acid rain. , Long-term exposure to NO 2 , even at the part per billion (ppb) level, may cause serious diseases. , Therefore, accurate detection of NO 2 at ppb level in the air is important to environmental conservation and human health.…”

“…3,4 Long-term exposure to NO 2 , even at the part per billion (ppb) level, may cause serious diseases. 5,6 Therefore, accurate detection of NO 2 at ppb level in the air is important to environmental conservation and human health.…”

“…Our previous series of works proposed that the concept of ion-in-conjugation (IIC) ,,− could endow the sensory materials with strong interactions with NO 2 molecules because the zwitterionic groups in the ion-in-conjugation can induce hydrogen-bonding and ion-dipole interactions, which could enhance the competitive adsorption capability of NO 2 molecules. Additionally, the strong inter-/intramolecular interactions benefitting ion-in-conjugation molecules effectively improve the robustness to external stimulus, allowing sensory devices to work under high temperatures, which could effectively reduce the interference from water molecules.…”