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Development of high‐performance dopant‐free hole‐transporting materials (HTMs) with comprehensive passivation effects is highly desirable for all‐inorganic perovskite solar cells (PVSCs). Squaraines (SQs) could be a candidate for dopant‐free HTMs as they are natural passivators for perovskites. One major limitation of SQs is their relatively low hole mobility. Herein we demonstrate that polymerizing SQs into pseudo two dimensional (2D) p–π conjugated polymers could overcome this problem. By rationally using N,N‐diarylanilinosquaraines as the comonomers, the resulting polysquaraine HTMs not only exhibit suitable energy levels and efficient passivation effects, but also achieve very high hole mobility close to 0.01 cm−2 V−1 s−1. Thus as dopant‐free HTMs for α‐CsPbI2Br‐based all‐inorganic PVSCs, the best PCE reached is 15.5 %, outperforming those of the doped‐Spiro‐OMeTAD (14.4 %) based control devices and among the best for all‐inorganic PVSCs. [ABSTRACT FROM AUTHOR]

Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such as the synthetic history, an understanding of the molecular structure, an overview of the optical properties, a discussion of both the electrical conduction properties, and magnetic properties, plus use of the particles of pyrrolyl squaraines, are presented. Furthermore, previously published results are not just presented; they are in certain cases collated and used to both highlight and explain important aspects of pyrrolyl squaraine chemistry.

Various conjugated polymer materials have been successfully applied in humidity sensors, but their response/recovery time are not satisfactory for breath humidity monitoring. In this research, a rapid and stable humidity sensor was fabricated from a polysquaraine, poly(1-phenylpyrrole-2-ylsquaraine) (PPPS) sample decorated by Au nanoparticles. Uniform PPPS microspheres in diameter were synthesized and loaded by gold nanoparticles (30 nm in diameter), and the structure was confirmed by X-ray photoelectron spectra and elemental mapping. Relative humidity (RH) values within the range of 11–95% were determined by testing the impedance response of the sensor at room temperature. The PPPS-2 sensor loaded with Au nanoparticles with 10% weight ratio to squaric acid offered the best humidity-sensing performance: the working range spreads from 11% to 95% RH; the response/recovery time is <1/4 s; its impedance variation reaches five orders of magnitude; the maximum hysteresis is 5%. Such a performance is attributed to electrical loading by gold and hydronium transportation. A portable device was fabricated for remote monitoring of breath humidity. Our results demonstrated that surface-engineered polysquaraines are of practical application in humidity measurement, and in particular, in breathing humidity monitoring. [ABSTRACT FROM AUTHOR]

Various materials have been successfully applied in commercial humidity sensors, but their response/recovery time and sensitivity need to be improved. In this paper, a novel humidity sensor was fabricated based on a polysquaraine (PMPS), which is of resonance-stabilized zwitterionic structure. Relative humidity (RH) in the range of 33–95% was able to determine by testing the impedance response at room temperature (25 °C). The variation of impedance is greater than four orders of magnitude, the highest among all conjugated polymer materials. The response/recovery time is as short as 3/16 s, comparable to that of most commercial humidity sensors. Electrical doping and hydronium transportation are attributed to the impedance change. The results indicate that polysquaraines may be promising materials in humidity sensing. [ABSTRACT FROM AUTHOR]

The article reports an experimental study of the metal uptake properties of poly(1-methylpyrrol-2-ylsquaraine) particles, in the context of 51 elemental metal complexes. Vagaries of the experimental results meant that the final analysis took place for 43 of these metals. After an initial descriptive analysis, an Analysis of Variance model was fitted. This revealed that several factors, some intrinsic to the metals themselves, others relating to the experimental conditions, have an important influence on the adsorption characteristics of the poly(1-methylpyrrol-2-ylsquaraine) particles. Of these, the most important is the ratio of the number of moles of the metal to the number of moles of the adsorbent particles. X-ray mapping of the poly(1-methylpyrrol-2-ylsquaraine) particles treated with contrast agent revealed that, although adsorption was all throughout the particles, the majority of the agent was adsorbed within 10-15% (diameter distance) of the surface of the particles. [ABSTRACT FROM AUTHOR]

Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such as the synthetic history, an understanding of the molecular structure, an overview of the optical properties, a discussion of both the electrical conduction properties, and magnetic properties, plus use of the particles of pyrrolyl squaraines, are presented. Furthermore, previously published results are not just presented; they are in certain cases collated and used to both highlight and explain important aspects of pyrrolyl squaraine chemistry. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report the synthesis of a series of eight polymeric pyrrolic squaraines. [•] The polysquaraines are studied using IR, XRD, TGA and SEM techniques. [•] Two of the eight polysquaraines electrically conduct (∼1×10−5 S/cm). [•] The two conductive polysquaraines are suspected to be flat and closely π-stacked. [•] Comment is made their structure/property relationship. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report the synthesis of a novel polysquaraine. [•] Prepared disks of the polysquaraine display large magneto-optic effects. [•] Disk samples also return saturation magnetization values of 4.13×10−3 emug−1. [•] All observations are commensurate with magnetism of a reduced dimensional nature. [ABSTRACT FROM AUTHOR]

In this study, we synthesised poly(3-octylpyrrole-co-squaric acid) (PSQ3), a polysquaraine, through the reaction of 3-octylpyrrole and squaric acid, and then co-doped it with phenanthrenequinone (PQ) into poly(methyl methacrylate) (PMMA) to improve the holographic data storage characteristics of the photopolymer. The photopolymers co-doped with relatively small amounts of PSQ3 exhibited greatly improved holographic recording characteristics, including superior diffraction efficiency and dynamic range (M#). Among the samples co-doped with PQ and PSQ3, the maximum diffraction efficiency reached 54.8% (cf. 9.0% for PMMA/PQ) without further downgrade and the value of M# reached 1.05 (cf. 0.46 for PMMA/PQ). Therefore, the holographic data storage characteristics of the photopolymer PMMA/PQ were improved through co-doping with PSQ3. [ABSTRACT FROM AUTHOR]

Abstract: Poly(1-octylpyrrolyl)squaraine and poly(3-octylpyrrolyl)squaraine were synthesized from squaric acid with 1-octylpyrrole and 3-octylpyrrole under identical conditions of condensation. Visible absorption spectra, photoluminescence spectra, TGA curves, and IR spectra were recorded to characterize the structures of these polymers as synthesized; the measured optical and thermal properties are consistent with backbone structures. The polysquaraine from 3-octylpyrrole possesses mostly zwitterionic repeating units (>97%), but the polymer from 1-octylpyrrole consists of zwitterionic and covalent repeating units in a ratio 2:1. Observations from the visible absorption and photoluminescence spectra in varied solvents, TGA curves, and thermal IR measurements for these two polymers reconciled to their structures. This result indicates that the position of the alkyl group in the pyrrole derivative affects the conformation in the condensation of poly(pyrrolyl)squaraine. These polysquaraines are stable below temperature 155°C and their visible absorption and photoluminescence properties in hydrogen-bonding solvents exhibit negative solvatochromism. [Copyright &y& Elsevier]

Several different methods are established for the analysis of gases, including optical spectroscopy, photoacoustic spectroscopy as well as colorimetric and resistive sensing, the measurements systems are either too complex or have limited sensitivity. In particular, when the goal is to apply a large number of sensors in networks, it is highly desirable to have devices that are simple, have low cost and energy consumption, yet sensitive and selective to monitor analytes even in traces. Herein, we propose a new type of resistive sensor device based on a composite of single-wall carbon nanotubes and an ion-in-conjugation polymer, poly(1,5-diaminonaphthalene-squaraine), capable of detecting H 2 S and NH 3 in air even at room temperature with a theoretical concentration limit of ~1 ppb and ~7 ppb, respectively. Density functional theory calculations revealed that H atoms of the analytes and O atoms of the polymer chain interact and form hydrogen bonds, and the electron withdrawal from the gas molecules by the polymer chain results in the change of its electrical conductivity. To demonstrate the feasibility of the new nanocomposites in sensing, we show the devices for monitoring food safety with good sensor stability of operation for at least 3 months of period of time., (© 2021 IOP Publishing Ltd.)