Ion‐in‐Conjugation: Squaraine as an Ultrasensitive Ammonia Sensor Material

Abstract

An organic thin-film gas sensor based on squaraine detects ammonia as low as 40 ppb with impressive reversibility and stability. The resonance-stabilized zwitterionic characteristics offer squaraines high affinity and sensitivity toward electron-rich analytes without irreversible chemical binding, while the embedded squaric ring makes SA-CH highly sensitive. The symmetric molecular geometry and good crystallinity also contribute to the high performance.

Detection of NO2 Down to One ppb Using Ion‐in‐Conjugation‐Inspired Polymer

“…In this regard, ion‐dipole attraction and H‐bonding appear as opportune candidates to achieve adequate interaction strength but no formation of irreversible covalent/ionic bond. Our previous work proposed an ion‐in‐conjugation principle, which proves that zwitterionic resonance molecules may offer ionic group to offer ion‐dipole attraction to detect ammonia with an LOD as low as 40 ppb, which is the lowest among all organic ammonia sensors …”

Better Organic Ternary Memory Performance through Self‐Assembled Alkyltrichlorosilane Monolayers on Indium Tin Oxide (ITO) Surfaces

“…All fresh organic films regardless of the ITO substrates have two crystalline phases, as revealed in Figures f–j. There are two arcs along the q z direction with some angular extension, indicating an ordered lamellar structure parallel to the ITO substrate, as illustrated in Figure S4 b in the Supporting Information. These arcs suggest interlayer spacing distances of about 24.9 ( q z =0.25) and 22.4 Å ( q z =0.28 Å −1 ).…”

“…Considering the molecular dimension and our previous study, these two spacings correspond to two crystal phases with different molecular tilt angles and different spacings . It is worth noting that here the arcs have a much wider angular distribution (mosaicity) than in the case of SA‐Bu on phosphonic acid SAM‐modified ITO, suggesting that the alkyltrichlorosilane SAMs are not as effective as phosphonic acid SAMs for the surface modification of ITO to induce the growth of an organic layer.…”

Naphthyl End‐Capped Terthiophene‐Based Chemiresistive Sensors for Biogenic Amine Detection and Meat Spoilage Monitoring

“…As reported by others [31][32][33][34][35][36] regarding the sensingm echanism, in organic chemiresistive devices, there are many shallow charge traps below the transport energy.I ti st he presence of these traps that allows the thermal production andh opping of charge carriers;t hus resulting in charge transportation. [50] It is well known that NA-3T-NA and NA-3T are p-type organic semiconductors, and thus, ap ossible sensingm echanism for the compound-based sensors can be illustrated as follows:F irst, BAs are adsorbed on the surface of the film, then electrons transfer from BAs to the nearest thiophener ings of the compounds,f ollowed by ad iffusion to charge traps throught he stacked molecules of the terthiophene derivatives within the active layer.U ndoubtedly,f illed traps are beneficial for conduction, leadingt oa ni ncreasei nt he current.…”

“…[30] Recently,L ua nd co-workers disclosed as quarainebased chemiresistive sensor,w hich showedr emarkable stability,a long with af ast and sensitive response to the presence of NH 3 ,w ith aD La sl ow as 40 ppb. [31] However,t he development of chemiresistive BAs sensors still remains ac hallenge because the kinds of materials used as an activel ayer remain few,t o date. Moreover,afaster response/recovery time and higherstability of devices are also neededf or further progress in this area of research.…”