Molecular Material‐Based Conductimetric Gas Sensors

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We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), poly(acrylic acid-co-acrylamide) (PAA-AM), poly(diallyldimethylammonium chloride) (PDDA) and polyaniline (PANI) as polymers. We also studied the response to ammonia (NH3) of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH) variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL) technique allowed to stabilize the film, but was too insulating to be interesting. We also prepared PANI-CuTsPc hybrid films by LBL technique. It allowed a regular deposition as evidenced by the linear increase of the absorbance at 688 nm as a function of the number of bilayers. The sensitivity to ammonia (NH3) of PANi-CuTsPc resistors was very high compared to that of individual materials, giving up to 80% of current decrease when exposed to 30 ppm NH3. Contrarily to what happens with neutral polymers, in PANI, CuTsPc was stabilized by strong electrostatic interactions, leading to a stable response to NH3, whatever the relative humidity in the range 10%–70%. Thus, the synergy of PANI with ionic macrocycles used as counteranions combined with their simple aqueous solution processing opens the way to the development of new gas sensors capable of operating in real world conditions.

Section: Introductionmentioning

confidence: 99%

From the Solution Processing of Hydrophilic Molecules to Polymer-Phthalocyanine Hybrid Materials for Ammonia Sensing in High Humidity Atmospheres

Gaudillat

Jurin

Lakard

et al. 2014

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“…In the last two decades, apart from inorganic materials, the sensing efficiency and stability of organic semiconducting materials has gathered lots of attention from researchers [ 66 ]. However, the light effect on molecular semiconducting materials only started to be used in gas-sensing applications very recently.…”

Section: Enhancement In Gas-sensing Properties Of the Sensors Under V...mentioning

confidence: 99%

Effects of Visible Light on Gas Sensors: From Inorganic Resistors to Molecular Material-Based Heterojunctions

Ganesh Moorthy,

Bouvet

2024

In the last two decades, many research works have been focused on enhancing the properties of gas sensors by utilising external triggers like temperature and light. Most interestingly, the light-activated gas sensors show promising results, particularly using visible light as an external trigger that lowers the power consumption as well as improves the stability, sensitivity and safety of the sensors. It effectively eliminates the possible damage to sensing material caused by high operating temperature or high energy light. This review summarises the effect of visible light illumination on both chemoresistors and heterostructure gas sensors based on inorganic and organic materials and provides a clear understanding of the involved phenomena. Finally, the fascinating concept of ambipolar gas sensors is presented, which utilised visible light as an external trigger for inversion in the nature of majority charge carriers in devices. This review should offer insight into the current technologies and offer a new perspective towards future development utilising visible light in light-assisted gas sensors.

“…CuTp-methoxyPC (2) To achieve wider chemical characterization of the devices based on the c complexes and LuPc2, they were studied by Raman spectroscopy (Table S1). Some correspond to the sublayer, at 646, 1016, 1080, 1340 cm −1 (Cα-Cα bonds), and an i peak at 1529 cm −1 attributed to C-F binding, while other peaks can be assigned to t layer LuPc2, namely 578 cm −1 corresponding to Pc breathing, at 780 cm −1 to C= breathing, at 1408 cm −1 to Cα-Cmeso, and at 1601 cm −1 to C=C in the benzene ring [3 Therefore, the Raman spectrum of the 1/LuPc2 heterostructure shows peaks that attributed to the two layers (Figure 5).…”

Section: Spectroscopic Characterizationmentioning

confidence: 99%

“…Sensors 2023, 23, x FOR PEER REVIEW 2 of 15 highly studied [1][2][3][4]. They are characterized by large π-aromatic systems and can reversibly interact with many molecules, by H-bonds and dipole-dipole and van der Waals interactions, with their metal center offering coordination bonding.…”

Section: Introductionmentioning

confidence: 99%

“…Among gas-sensing materials, molecular materials have been extensively studied because they offer lots of possibilities to tune their electrical and optical properties and the intermolecular interactions that they can develop with the target species. Among molecular materials, porphyrinoids, namely phthalocyanines and porphyrins, have been highly studied [ 1 , 2 , 3 , 4 ]. They are characterized by large π-aromatic systems and can reversibly interact with many molecules, by H-bonds and dipole–dipole and van der Waals interactions, with their metal center offering coordination bonding.…”

Section: Introductionmentioning

confidence: 99%

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Ammonia and Humidity Sensing by Phthalocyanine–Corrole Complex Heterostructure Devices

Di Zazzo,

Ganesh Moorthy,

Meunier-Prest

et al. 2023

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The versatility of metal complexes of corroles has raised interest in the use of these molecules as elements of chemical sensors. The tuning of the macrocycle properties via synthetic modification of the different components of the corrole ring, such as functional groups, the molecular skeleton, and coordinated metal, allows for the creation of a vast library of corrole-based sensors. However, the scarce conductivity of most of the aggregates of corroles limits the development of simple conductometric sensors and requires the use of optical or mass transducers that are rather more cumbersome and less prone to be integrated into microelectronics systems. To compensate for the scarce conductivity, corroles are often used to functionalize the surface of conductive materials such as graphene oxide, carbon nanotubes, or conductive polymers. Alternatively, they can be incorporated into heterojunction devices where they are interfaced with a conductive material such as a phthalocyanine. Herewith, we introduce two heterostructure sensors combining lutetium bisphthalocyanine (LuPc2) with either 5,10,15-tris(pentafluorophenyl) corrolato Cu (1) or 5,10,15-tris(4-methoxyphenyl)corrolato Cu (2). The optical spectra show that after deposition, corroles maintain their original structure. The conductivity of the devices reveals an energy barrier for interfacial charge transport for 1/LuPc2, which is a heterojunction device. On the contrary, only ohmic contacts are observed in the 2/LuPc2 device. These different electrical properties, which result from the different electron-withdrawing or -donating substituents on corrole rings, are also manifested by the opposite response with respect to ammonia (NH3), with 1/LuPc2 behaving as an n-type conductor and 2/LuPC2 behaving as a p-type conductor. Both devices are capable of detecting NH3 down to 10 ppm at room temperature. Furthermore, the sensors show high sensitivity with respect to relative humidity (RH) but with a reversible and fast response in the range of 30–60% RH.