Narrow Results

Phthalocyanines are organic-based materials which have attracted a lot of research in recent times. In the field of sensors, they present interesting and valuable potentialities as sensing elements for real gas sensor applications. In the present article, and taking some of our experiments as representative examples, we review the different ways of transduction applied to such applications. Some of the new tendencies and transducers for gas sensing based on phthalocyanine derivatives are also reported. Among them, electrical transduction (resistors, field-effect transistors, diodes, etc.) has been, historically, the most commonly exploited way for the detection and/or quantification of gas pollutants, vapors and aromas, according to the conducting behavior of phthalocyanines. We will focus precisely on these systems.

Solvent vapor atmosphere is introduced for solution-evaporated poly(3-hexylthiophene) (P3HT) formation in fabricating organic field-effect transistors (OFETs). As changing the solvent vapor atmosphere, prominent influences on the assemblies of P3HT nanowires during solidification were represented, leading to the difference in nanostructure morphologies. We demonstrated that the device fabricated under anisole solvent vapor atmosphere is superior in electrical performance to that of the devices fabricated under other conditions. In this process, anisole solvent vapor atmosphere transparently facilitated one-dimensional (1D) self-assembly through π–π stacking interaction among the P3HT units during solidification.

Single-walled carbon nanotubes (SWCNTs) with incovalently attached iodine, were obtained by physical absorption. The different diameter sizes of SWCNTs, with different numbers of iodine molecule, enhance the density contrast between them which becomes evident in density gradient ultracentrifugation (DGU) targeted to sort certain species of SWCNTs. The results of optical absorbance and photoluminescence emission showed that iodine-assisted DGU preferentially separates semiconducting nanotubes with certain diameters [(6, 5), (7, 5), (8, 4), and (7, 6)].We have applied these semiconducting, species enriched SWCNTs to prepare solution-processed field effect transistor (FET) devices with random nanotube network active channels. The devices exhibit stable p-type semiconductor behavior in air with very promising characteristics. The on-off current ratio reaches up to 2 × 10⁴ within a narrow window of voltage (-10 V to 10 V), and estimated hole mobility of 21.7 cm² V^-1 s^-1.

Progress in electronics is limited by power dissipation constraints. Ferroelectric materials with a negative capacitance could help to overcome these limits. Especially, HfO₂ and ZrO₂ based ferroelectrics are promising for negative capacitance electronics due to their compatibility with modern transistor manufacturing processes. Recently, first negative capacitance transistors have been demonstrated. However, further investigations on the microscopic origin of negative capacitance in HfO₂- and ZrO₂-based ferroelectrics are needed. Lastly, opportunities for negative capacitance beyond transistors are discussed.