Efficient Selective Sorting of Semiconducting Carbon Nanotubes Using Ultra-Narrow-Band-Gap Polymers

Conjugated polymers with narrow band gaps are particularly useful for sorting and discriminating semiconducting single-walled carbon nanotubes (s-SWCNT) due to the low charge carrier injection barrier for transport. In this paper, we report two newly synthesized narrow-band-gap conjugated polymers (PNDITEG-TVT and PNDIC8TEG-TVT) based on naphthalene diimide (NDI) and thienylennevinylene (TVT) building blocks, decorated with different polar side chains that can be used for dispersing and discriminating s-SWCNT. Compared with the mid-band-gap conjugated polymer PNDITEG-AH, which is composed of naphthalene diimide (NDI) and head-to-head bithiophene building blocks, the addition of a vinylene linker eliminates the steric congestion present in head-to-head bithiophene, which promotes backbone planarity, extending the π-conjugation length and narrowing the band gap. Cyclic voltammetry (CV) and density functional theory (DFT) calculations suggest that inserting a vinylene group in a head-to-head bithiophene efficiently lifts the highest occupied molecular orbital (HOMO) level (-5.60 eV for PNDITEG-AH, -5.02 eV for PNDITEG-TVT, and -5.09 eV for PNDIC8TEG-TVT). All three polymers are able to select for s-SWCNT, as evidenced by the sharp transitions in the absorption spectra. Field-effect transistors (FETs) fabricated with the polymer:SWCNT inks display p-dominant properties, with higher hole mobilities when using the NDI-TVT polymers as compared with PNDITEG-AH (0.6 cm² V^-1 s^-1 for HiPCO:PNDITEG-AH, 1.5 cm² V^-1 s^-1 for HiPCO:PNDITEG-TVT, and 2.3 cm² V^-1 s^-1 for HiPCO:PNDIC8TEG-TVT). This improvement is due to the better alignment of the HOMO level of PNDITEG-TVT and PNDIC8TEG-TVT with that of the dominant SWCNT specie.

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.

Donor-acceptor-donor (D-A-D) structural monomers as donor materials in polymer solar cells: a DFT/TDDFT approach

Density functional theory (DFT) and time-dependent DFT (TD-DFT) are used to investigate the ground- and excited-state properties of donor-acceptor-donor (D-A-D) monomers based on 3,6-carbazole (CB) combined with various-conjugated benzothiazole derivatives, using B3LYP and the 6-311 G basis set. To create nine D-A-D monomers for this investigation, nine (9) distinct acceptors were inserted at the C3 and C6 positions of carbazole. The impact of various electron-donor groups on structural, electrical, and optoelectronic properties is investigated. Our technique for developing novel donor monomers provides a theoretical framework for further optimizing the photovoltaic device's electrical, optical, and efficiency features. The HOMO and LUMO energies, bandgap, excited state, exciton binding energy, open-circuit voltage (VOC) and absorption spectra were calculated. Our findings indicate that CB-TDP-CB and CB-SDP-CB monomers have an appropriate electronic structure for polymer solar cells.

Transient absorption spectroscopy of the electron transfer step in the photochemically activated polymerizations of N-ethylcarbazole and 9-phenylcarbazole

The polymerization of photoexcited N-ethylcarbazole (N-EC) in the presence of an electron acceptor begins with an electron transfer (ET) step to generate a radical cation of N-EC (N-EC˙+). Here, the production of N-EC˙+ is studied on picosecond to nanosecond timescales after N-EC photoexcitation at a wavelength λex = 345 nm using transient electronic and vibrational absorption spectroscopy. The kinetics and mechanisms of ET to diphenyliodonium hexafluorophosphate (Ph2I+PF6-) or para-alkylated variants are examined in dichloromethane (DCM) and acetonitrile (ACN) solutions. The generation of N-EC˙+ is well described by a diffusional kinetic model based on Smoluchowski theory: with Ph2I+PF6-, the derived bimolecular rate coefficient for ET is kET = (1.8 ± 0.5) × 1010 M-1 s-1 in DCM, which is consistent with diffusion-limited kinetics. This ET occurs from the first excited singlet (S1) state of N-EC, in competition with intersystem crossing to populate the triplet (T1) state, from which ET may also arise. A faster component of the ET reaction suggests pre-formation of a ground-state complex between N-EC and the electron acceptor. In ACN, the contribution from pre-reaction complexes is smaller, and the derived ET rate coefficient is kET = (1.0 ± 0.3) × 1010 M-1 s-1. Corresponding measurements for solutions of photoexcited 9-phenylcarbazole (9-PC) and Ph2I+PF6- give kET = (5 ± 1) × 109 M-1 s-1 in DCM. Structural modifications of the electron acceptor to increase its steric bulk reduce the magnitude of kET: methyl and t-butyl additions to the para positions of the phenyl rings (para Me2Ph2I+PF6- and t-butyl-Ph2I+PF6-) respectively give kET = (1.2 ± 0.3) × 1010 M-1 s-1 and kET = (5.4 ± 1.5) × 109 M-1 s-1 for reaction with photoexcited N-EC in DCM. These reductions in kET are attributed to slower rates of diffusion or to steric constraints in the ET reaction.

Theoretical studies of optoelectronic and photovoltaic properties of D-A polymer monomers by Density Functional Theory (DFT)

In this research article, the new donor–acceptor (D–A) monomers developed using 4-methoxy-9-methyl-9 H-carbazole (MMCB) as electron donors and various electron acceptors. DFT and TD-DFT methods at the level of B3LYP with a 6–311 G basis set in a gas and chloroform solvent were used to calculate electronic and optoelectronic properties. To dissect the relationship between the molecular and optoelectronic structures, the impacts of specific acceptors on the geometry of molecules and optoelectronic properties of these D–A monomers were discussed. The calculations are also carried out on HOMO–LUMO, atomic orbital densities. The calculated band gap E_g of the monomers considered increases 3,6-MMCB-OCP ≈ 3,6-MMCB-BCO < 3,6-MMCB-SDP < 3,6-MMCB-SCP < 3,6-MMCB-TCP < 3,6-MMCB-TDP < 3,6-MMCB-BCS < 3,6-MMCB-BCT in both in the gas and solvent phases. Subsequently, the optoelectrical properties of E_HOMO, E_LUMO, E_opt, and E_B energies were critically updated. Compared to different monomers, the far lower E_g of the 3,6-MMCB-OCP and 3,6-CB-BCO has shown optoelectronic applications in organic solar cells like BHJ.

Theoretical design of low bandgap donor-acceptor (D-A) monomers for polymer solar cells: DFT and TD-DFT study

Endeavors have been made to construct new donor-acceptor (D-A) monomers utilizing 9 H-carbazole (CB) as electron donors and different electron acceptors. All estimations were finished using DFT and TD-DFT, and B3LYP level with a 6-311 G basis set in the gas and chloroform solvent. The impacts of the distinctive acceptors on the geometry of molecules and optoelectronic properties of these D-A monomers were discussed to dissect the connection connecting the molecular structures and the optoelectronic properties. Likewise, the HOMO - LUMO energies, atomic orbital densities are calculated theoretically. Notwithstanding the charge transfer measure between the carbazole electron donor unit and the electron acceptor one is upheld by breaking down the optical spectra of the acquired monomers and the restriction of involved HOMO and LUMO. The outcomes show that the D-A monomers, CB-ODP, CB-TDP, and CB-SDP, are acceptable for optoelectronic applications in organic solar cells like BHJ.

Polycarbazole and Its Derivatives: Synthesis and Applications. A Review of the Last 10 Years

Polycarbazole and its derivatives have been extensively used for the last three decades, although the interest in these materials briefly decreased. However, the increasing demand for conductive polymers for several applications such as light emitting diodes (OLEDs), capacitators or memory devices, among others, has renewed the interest in carbazole-based materials. In this review, the synthetic routes used for the development of carbazole-based polymers have been summarized, reviewing the main synthetic methodologies, namely chemical and electrochemical polymerization. In addition, the applications reported in the last decade for carbazole derivatives are analysed. The emergence of flexible and wearable electronic devices as a part of the internet of the things could be an important driving force to renew the interest on carbazole-based materials, being conductive polymers capable to respond adequately to requirement of these devices.

Separation of Semiconducting Carbon Nanotubes Using Conjugated Polymer Wrapping

In the past two decades, single-walled carbon nanotubes (SWNTs) have been explored for electronic applications because of their high charge carrier mobility, low-temperature solution processability and mechanical flexibility. Semiconducting SWNTs (s-SWNTs) are also considered an alternative to traditional silicon-based semiconductors. However, large-scale, as-produced SWNTs have poor solubility, and they are mixtures of metallic SWNTs (m-SWNTs) and s-SWNTs, which limits their practical applications. Conjugated polymer wrapping is a promising method to disperse and separate s-SWNTs, due to its high selectivity, high separation yield and simplicity of operation. In this review, we summarize the recent progress of the conjugated polymer wrapping method, and discuss possible separation mechanisms for s-SWNTs. We also discuss various parameters that may affect the selectivity and sorting yield. Finally, some electronic applications of polymer-sorted s-SWNTs are introduced. The aim of this review is to provide polymer chemist a basic concept of polymer based SWNT separation, as well as some polymer design strategies, influential factors and potential applications.

Recent advances in poly(3,4-ethylenedioxyselenophene) and related polymers

This review highlights the recent progress in synthesis, properties, applications and future outlook of PEDOS based conjugated polymers.

Improving the Electropolymerization Properties of Fluorene-Bridged Dicarbazole Monomers through Polyfluoroalkyl Side Chains

The facile functionalization of the fluorene scaffold at the 2,7-positions was utilized to provide access to two soluble carbazole-π-carbazole derivatives CFC-H1 and CFC-F1 featuring fully hydrogenated and polyfluorinated alkyl chains at the 9-position of the fluorene π-bridging unit, respectively. The optical and electrochemical properties of the new dicarbazoles were investigated. Their electrochemical polymerization over Pt and indium tin oxide electrodes allowed the generation of electroactive polymeric films, whose physicochemical characteristics were strongly dependent on the kind of alkyl chain present on the fluorene bridge. In particular, the electropolymerization of the polyfluorinated monomer allowed the fabrication of thin films with good electrical conductivity, reversible electrochemical processes, good electrochromic properties, and enhanced water repellency with respect to its nonfluorinated analogue.

Synthesis and Ring-Opening Metathesis Polymerization of a New Norbornene Dicarboximide with a Pendant Carbazole Moiety

A new norbornene dicarboximide presenting a pendant carbazole moiety linked by a p-methylene benzyl spacer is synthesized. This carbazole-functionalized monomer is polymerized via ring-opening metathesis polymerization using Grubbs third-generation catalyst. Microstructural analysis of resulting polymers performed by Nuclear Magnetic Resonance (NMR) shows that they are stereoirregular. Wide-angle X-ray diffraction (WAXD) and thermal (DSC) analysis indicate that polymers are also amorphous. With respect to the fluorescence analysis, both solution and film polymer samples exhibit only “normal structured” carbazole fluorescence, while excimer formation by overlap of carbazole groups is not detected.

Photoinduced synthesis of poly(N-ethylcarbazole) from phenacylium salt without conventional catalyst and/or monomer

We report a new method for the photoinduced synthesis of poly(N-ethylcarbazole) (PEC).

Iodo-Cycloisomerization of Aryl(indol-3-yl)methane-Tethered Propargyl Alcohols to 3-Iodocarbazoles via Selective 1,2-Alkyl Migration

Herein, we disclose the first report on iodo-cycloisomerization of 1-(indol-3-yl)-1-arylbut-3-yn-2-ols to form 3-iodocarbazoles. The synthesis proceeds through a cascade 5-endo-spirocyclization, followed by selective 1,2-alkyl migration. This method governs the green synthesis principles such as open-flask reaction, AcOEt as the solvent, rt reaction with short time, use of iodine, and broad substrate scope with atom and step economy.

Study of the mechanoluminescence and ‘aggregation-induced emission enhancement’ properties of a new conjugated oligomer containing tetraphenylethylene in the backbone: application in the selective and sensitive detection of explosive

D–π-A based ‘Aggregation-Induced Emission Enhancement (AIEE)’ active conjugated oligomer (oTPETP) exhibits an abnormal blue shifting mechanoluminescence and selective and sensitive detection of explosive.

Facile Synthesis of Electroactive and Electrochromic Triptycene Poly(ether-imide)s Containing Triarylamine Units via Oxidative Electro-Coupling

Two bisimide compounds, TPA–TPDI and NPC–TPDI, consisting of a triptycene core and two triphenylamine (TPA) or N-phenylcarbazole (NPC) end groups were successfully synthesized by the condensation reactions from 1,4-bis(3,4-dicarboxyphenoxy)triptycene dianhydride with 4-aminotriphenylamine and N-(4-aminophenyl)carbazole, respectively. These two monomers could polymerize electrochemically via the oxidative coupling reactions of triarylamine units. The electrochemical and spectroelectrochemical properties of the electro-generated triptycene poly(ether-imide)s (TPA–TPPI and NPC–TPPI) were studied. Both polymers have two colored oxidation states, and TPA–TPPI showed better electrochromic performance than NPC–TPPI.

3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic-organic hybrid perovskite solar cells

The ever increasing demand for clean energy has encouraged researchers to intensively investigate environmentally friendly photovoltaic devices. Inorganic-organic hybrid perovskite solar cells (PSCs) are very promising due to their potentials of easy fabrication processes and high power conversion efficiencies (PCEs). Designing hole-transporting materials (HTMs) is one of the key factors in achieving the high PCEs of PSCs. We now report the synthesis of two types of carbazole-based polymers, namely 3,6-Cbz-EDOT and 2,7-Cbz-EDOT, by Stille polycondensation. Despite the same chemical composition, 3,6-Cbz-EDOT and 2,7-Cbz-EDOT displayed different optical and electrochemical properties due to the different connectivity mode of the carbazole unit. Therefore, their performances as hole-transporting polymeric materials in the PSCs were also different. The device based on 2,7-Cbz-EDOT showed better photovoltaic properties with the PCE of 4.47% than that based on 3,6-Cbz-EDOT. This could be due to its more suitable highest occupied molecular orbital (HOMO) level and higher hole mobility.

Structural effects of dibromocarbazoles on direct arylation polycondensation with 3,4-ethylenedioxythiophene

Microwave-assisted direct arylation polycondensation of 3,4-ethylenedioxythiophene produced a solution processable and electrochromic polymer when 3,6-dibromocarbazole was employed as a comonomer.

Linkage and donor–acceptor effects on resistive switching memory devices of 4-(N-carbazolyl)triphenylamine-based polymers

In order to gain deeper insight about the linkage effect and donor–acceptor effect on memory behavior (from DRAM to WORM), 4-(N-carbazolyl)triphenylamine-based polyimides and polyamides were synthesized and their memory behaviours were investigated.

Electrochemically fabricated electrochromic films from 4-(N-carbazolyl)triphenylamine and its dimethoxy derivative

4-(N-Carbazolyl)triphenylamine (TPACz) and its methoxy derivative MeOTPACz could be facilely fabricated into redox-active and electrochromic PTPACz polymer and (MeOTPACz)2 dimer films via electrochemical polymerization.

Electrochemical synthesis of electrochromic polycarbazole films from N-phenyl-3,6-bis(N-carbazolyl)carbazoles

Electroactive and electrochromic polycarbazole films were directly prepared on electrodes from N-phenyl-3,6-bis(N-carbazolyl)carbazoles by carbazole-based electrochemical oxidative coupling.