Polycarbazole and its derivatives: progress, synthesis, and applications

Single/Multi-Network Conductive Hydrogels-A Review

Hydrogels made from conductive organic materials have gained significant interest in recent years due to their wide range of uses, such as electrical conductors, freezing resistors, biosensors, actuators, biomedical engineering materials, drug carrier, artificial organs, flexible electronics, battery solar cells, soft robotics, and self-healers. Nevertheless, the insufficient level of effectiveness in electroconductive hydrogels serves as a driving force for researchers to intensify their endeavors in this domain. This article provides a concise overview of the recent advancements in creating self-healing single- or multi-network (double or triple) conductive hydrogels (CHs) using a range of natural and synthetic polymers and monomers. We deliberated on the efficacy, benefits, and drawbacks of several conductive hydrogels. This paper emphasizes the use of natural polymers and innovative 3D printing CHs-based technology to create self-healing conductive gels for flexible electronics. In conclusion, advantages and disadvantages have been noted, and some potential opportunities for self-healing single- or multi-network hydrogels have been proposed.

Highly sensitive and specific detection of Ni2+ using a novel fluorometric probe in the DMSO-H2O system

The rapid detection of Ni ions has important research and application value. This paper presents a novel specific turn-off fluorescence probe PCTMP-FS for detecting Ni2+ ions. The carbazole-based compound PCTMP is first synthesized via a two-step reaction. PCTMP-FS comprises PCTMP dispersed into a DMSO-H2O (fw = 30% v/v) mixed solvent. The probe demonstrates prominent selectivity and anti-interference abilities for detecting Ni2+ with a limit of detection (LOD) of 0.233 μM. The probe exhibits good applicability over a wide range of acidities. The detecting mechanism of the probe is due to the complex formed by PCTMP and Ni2+ (2:1), which destroys intramolecular charge transfer in the compound. The probe has good repeatability and demonstrates excellent stability and sensitivity for the detection of Ni2+ in real water samples.

Exploring optical, electrochemical, thermal, and theoretical aspects of simple carbazole-derived organic dyes

This study highlights the recent advancements in organic electronic materials and their potential for cost-effective optoelectronic devices. The investigation focuses on the molecular design, synthesis, and comprehensive analysis of two organic dyes, aiming to explore their suitability for optoelectronic applications. The dyes are strategically constructed with carbazole as the foundational structure, connecting two electron-withdrawing groups: barbituric acid (Cz-BA) and thiobarbituric acid (Cz-TBA). These dyes, featuring carbazole as the core and electron-withdrawing groups, demonstrate promising spectral, optical, electrochemical, thermal, and theoretical properties. They show strong potential for diverse optoelectronic applications, promising efficient light absorption and robust stability. The results endorse their suitability for practical optoelectronic systems.

Advances in Hole Transport Materials for Layered Casting Solar Cells

Huge energy consumption and running out of fossil fuels has led to the advancement of renewable sources of power, including solar, wind, and tide. Among them, solar cells have been well developed with the significant achievement of silicon solar panels, which are popularly used as windows, rooftops, public lights, etc. In order to advance the application of solar cells, a flexible type is highly required, such as layered casting solar cells (LCSCs). Organic solar cells (OSCs), perovskite solar cells (PSCs), or dye-sensitive solar cells (DSSCs) are promising LCSCs for broadening the application of solar energy to many types of surfaces. LCSCs would be cost-effective, enable large-scale production, are highly efficient, and stable. Each layer of an LCSC is important for building the complete structure of a solar cell. Within the cell structure (active material, charge carrier transport layer, electrodes), hole transport layers (HTLs) play an important role in transporting holes to the anode. Recently, diverse HTLs from inorganic, organic, and organometallic materials have emerged to have a great impact on the stability, lifetime, and performance of OSC, PSC, or DSSC devices. This review summarizes the recent advances in the development of inorganic, organic, and organometallic HTLs for solar cells. Perspectives and challenges for HTL development and improvement are also highlighted.

A novel carbazole-based fluorometric and colorimetric sensor for the highly sensitive and specific detection of Cu2+ in aqueous solution

Based on the typical Suzuki coupling reaction and Schiff base reaction, a novel fluorescent molecular PCBW is synthesized and applied as a fluorescence and colorimetric sensor to detect Cu2+ in aqueous solution. The PCBW sensor presents the aggregation-caused quenching (ACQ) effect and at 1 × 10-5 mol L-1 it emits the strongest turquoise fluorescence in the DMSO-H2O system (fw = 40%). The sensor exhibits a 'turn-off' fluorescent characteristic by adding Cu2+, and its fluorescent intensity shows a reliable linear relationship with the Cu2+ concentration in the range of 0-6 × 10-6 mol L-1, with a detection limit of 1.19 × 10-8 mol L-1. Meanwhile, the PCBW sensor also exhibits the colorimetric sensing from colorless to light yellow. The sensor has good selectivity and anti-interference and its pH application range can be extended from 5 to 10. The intramolecular charge transfer (ICT) is speculated as the main fluorescence mechanism of PCBW. In addition, the sensor presents good reusability and is practicable to detect Cu2+ in diverse aqueous samples.

An environmentally insensitive fluorescent probe for G4 DNA detection: Design, synthesis, and mechanism studies

G4 DNA structure highly localized to functionally important sites within the human genome, has been identified as a biomarker for regulation of multiple biological processes. Identification G4-responsive fluorescence probes has broad application prospects for addressing G4 biological functions, as well as developing of new families of anticancer drugs. However, some currently designed G4 DNA probes may suffer from serious solvent-dependent effect, and cause unspecific fluorescence that masks the specific signal from G4 DNA. Herein, with a bulky imidazole-cored molecular rotor fusing in D-A building block of carbazole-pyridinium, we constructed a new probe ACPS. This new probe with desirable environmentally insensitive property exhibited a "fluorescence-off" state in various polarity solvents. In the presence of G4 DNA, the intra-molecular rotations would be restricted, triggering intense fluorescence enhancement. Especially, probe ACPS bound to G4 DNA structures with superior selectivity, exhibiting much weaker fluorescence response in the presence of non-G4 DNA structures. This probe was also able to realize fluorescence visualization in cell imaging. Collectively, the probe design strategy eliminates the background fluorescence caused by uncontrollable environmental polarity change, thereby achieving high-fidelity sensing G4 DNA structures in complicated systems.

A resistive sensor for humidity detection based on cellulose/polyaniline

Ambient humidity is an important parameter that affects the manufacturing and storage of several industrial and agricultural goods. In the view of the Internet of Things (IoT), single sensors could be associated with an object for smart monitoring enabling optimum conditions to be maintained. Nevertheless, the production of cost-effective humidity sensors for indoor and outdoor environmental monitoring currently represents the main bottleneck in the development of this technology. Herein we report the results obtained with sensors exclusively made of cellulose and polyaniline (cell/PANI) under strictly controlled relative humidity (30–50 RH%) and temperature (21 ± 1 °C) achieved with a climatic chamber that simulates the conditions of indoor air humidity, and at different RH% in a lab test chamber set-up. Cell/PANI sensors, prepared with a simple, inexpensive, and easily scalable industrial paper process, show a linear trend with a slope of 1.41 μA RH%⁻¹ and a percentage of sensitivity of 13%. Response time as well as percentage of sensitivity results are similar to those of a commercial digital-output relative humidity and temperature sensor (DHT22) employed in parallel for comparison. The commercial sensor DHT22 has a sensitivity of 14%. This low-cost sensor has potential applications in agriculture, food monitoring, and medical and industrial environments as a disposable sensor for humidity detection.

Preparation of highly conductive polyaniline-coated cellulose sheets for the fabrication of humidity sensors via a simple, inexpensive, and robust method. These sensors show a linear, rapid, and reliable response for humidity cycling.

Poly(carbazole-co-1,4-dimethoxybenzene): Synthesis, Electrochemiluminescence Performance, and Application in Detection of Fe3+

In this study, four polycarbazole derivatives (PCMB-Ds) with different alkyl side chains were designed and synthesized via Wittig–Horner reaction. A novel solid-phase electrochemiluminescence (ECL) system was prepared by immobilizing PCMB-D on an indium tin oxide (ITO) electrode with polyvinylidene fluoride (PVDF) in the presence of tripropylamine (TPrA). It could be found that the increase in alkyl side chain length had little effect on the ECL signal of PCMB-D, while the increase in the degree of polymerization (DP) greatly enhanced the ECL signal. Furthermore, the P-3/ITO ECL sensor based on the polyoctylcarbazole derivative (P-3) with the best ECL performance was successfully constructed and detected Fe³⁺ under the optimal experimental conditions. The ECL signal steadily diminished with the increased concentration of Fe³⁺ because of the competition and complexation between Fe³⁺ and P-3 under the condition of pH 7.4. This P-3/ITO platform could realize a highly sensitive and selective detection of Fe³⁺ with a wide detection range (from 6 × 10⁻⁸ mol/L to 1 × 10⁻⁵ mol/L) and low detection limit of 2 × 10⁻⁸ mol/L, which could allow the detection of Fe³⁺ in multiple scenarios, and would have a great application prospect.

Electrodeposition and Characterization of Conducting Polymer Films Obtained from Carbazole and 2-(9H-carbazol-9-yl)acetic Acid

Electrochemical oxidation of electrolyte solutions containing carbazole (Cz) and 2-(9H-carbazol-9-yl)acetic acid (CzA) monomers was performed in acetonitrile solutions. Different Cz and CzA feed ratios were used to electrodeposit solid polymer films of various compositions, and to study the influence of the monomer ratio on the physicochemical properties (electroactivity, topography, adhesion, stiffness, wettability) of the polymer films. Thus, electrochemical oxidation led to the deposition of a solid film of micrometric thickness, but only for the solutions containing at least 30% of Cz. The proportion of Cz and CzA in the electrodeposited polymer films has little impact on the adhesion strength values measured by AFM. On the contrary, this proportion significantly modifies the stiffness of the films. Indeed, the stiffness of the polymer films varies from 9 to 24 GPa depending on the monomer ratio, which is much lower than the value obtained for unmodified polycarbazole (64 GPa). This leads to the absence of cracks in the films, which all have a fairly homogeneous globular structure. Moreover, among the different polymer films obtained, those prepared from 70:30 and 50:50 ratios in Cz:CzA monomer solutions seem to be the most interesting because these green films are conductive, thick, low in stiffness, do not show cracks and are resistant to prolonged immersion in water.

EQCM Investigation of a Dual-Doped Polymer Electrode for Li-Ion Batteries with Improved Reversible Capacity

Polymer-based materials with the incorporation of redox-active dopants serve as promising electrodes for Li-ion batteries but their use is restricted by the limited doping level and inevitable dissolution behavior of the dopants. Here, we proposed a conjugated polymer-based electrode with an assistant dopant to realize the reversible capacity contribution of a redox-active dopant. By employing phosphate anion (PO) as the assistant dopant to stable the polymer matrix, the reversible capacity was improved by introducing indigo carmine (IC) into the polymer electrode. Based on the real-time monitoring of the electrochemical quartz crystal microbalance toward the mass change, the charge storage behavior of the redox-active dopant IC was observed and the stabilizing effect of the assistant dopant PO was revealed. The modified electrode delivered an increased capacity of 191 mA h g^-1, and the reversible capacity remained 56% higher than that of the PO-undoped electrode after 200 cycles. The dual-doping strategy with the assistant dopant and the redox-active dopant is used to develop advanced polymer-based electrodes for high-capacity and long-cycling batteries.

Development of Uniform Porous Carbons From Polycarbazole Phthalonitriles as Durable CO2 Adsorbent and Supercapacitor Electrodes

Advances in new porous materials have recognized great consideration in CO₂ capture and electrochemical energy storage (EES) applications. In this study, we reported a synthesis of two nitrogen-enriched KOH-activated porous carbons prepared from polycarbazole phthalonitrile networks through direct pyrolysis protocol. The highest specific surface area of the carbon material prepared by pyrolysis of p-4CzPN polymer reaches 1,279 m² g⁻¹. Due to the highly rigid and reticular structure of the precursor, the obtained c-4CzPN–KOH carbon material exhibits high surface area, uniform porosity, and shows excellent CO₂ capture performance of 19.5 wt% at 0°C. Moreover, the attained porous carbon c-4CzPN–KOH showed high energy storage capacities of up to 451 F g⁻¹ in aqueous electrolytes containing 6.0 M KOH at a current density of 1 A g^-1. The prepared carbon material also exhibits excellent charge/discharge cycle stability and retains 95.9% capacity after 2000 cycles, indicating promising electrode materials for supercapacitors.

Intrinsically conducting polymers and their combinations with redox-active molecules for rechargeable battery electrodes: an update

Intrinsically conducting polymers and their copolymers and composites with redox-active organic molecules prepared by chemical as well as electrochemical polymerization may yield active masses without additional binder and conducting agents for secondary battery electrodes possibly utilizing the advantageous properties of both constituents are discussed. Beyond these possibilities these polymers have found many applications and functions for various further purposes in secondary batteries, as binders, as protective coatings limiting active material corrosion, unwanted dissolution of active mass ingredients or migration of electrode reaction participants. Selected highlights from this rapidly developing and very diverse field are presented. Possible developments and future directions are outlined.