Thienylene Vinylene Research Articles

Synthesis and Brønsted acid doping of solution processable poly(thienylene vinylene) for thermoelectric application

Poly(thienylene vinylene) (PTV) with high molecular weight was obtained via transition-metal-free and halogen-free polymerization, and the Brønsted acid doping of the PTV film was used for thermoelectric application.

Low-cost and high-performance poly(thienylene vinylene) derivative donor for efficient versatile organic photovoltaic cells

The utilization of donor materials with complex structures obviously increases the costs of organic photovoltaic (OPV) cells. Therefore, low-cost and high-performance are two issues that must be considered when designing polymer donors for the preparations of large-area OPV cells. Here, a poly(thienylene vinylene) derivative, named PTVT-BT was reported. PTVT-BT has a very simple completely non-fused molecular structure. PTVT-BT shows planar molecular structure and obvious solution aggregation effect. Besides, PTVT-BT demonstrates a high hole mobility up to the magnitude of 10-2 cm-2 V-1 s-1. The external quantum efficiency of electroluminescence of PTVT-BT is 7 × 10-3. As a result, the OPV cell based on PTVT-BT:eC9 demonstrates a power conversion efficiency (PCE) of 16.31%, which is the highest value among the poly(thienylene vinylene)- and polythiophene-based OPV cells. The tandem OPV cell with PTVT-BT as the donor of the sub-cell yields an outstanding PCE of 18.49%. Besides, the indoor OPV cell based on PTVT-BT:BTA3 exhibits a PCE of 27.30% under a light-emitting diode (LED) illumination of 1000 lux (2700 K). This study indicates that PTV-derivative is a kind of promising material for the future OPV industrialization.

Regio‐regular and cross‐conjugated poly(thienylene vinylene)s through acyclic diene metathesis

AbstractPoly(thienylene vinylene)s (PTV's) are early examples of conjugated polymers but have not been extensively studied when compared with closely analogous polythiophenes. PTV's synthesized through previously reported techniques are similar in structures that contain various alkyl or alkoxy side‐chains that exert limited impact on the polymer electronic properties. Herein, we report the preparation of a series of regio‐regular PTV's (rr‐PTV's) bearing cross‐conjugated side‐chains through ADMET polymerization of a common brominated di(thienylene vinylene) (DTV) monomer followed by PPM reactions on the resulting brominated PTV. These new polymers contain a bulky silyloxy alkyl side‐chain and a functionalized thiophene moiety on every main‐chain thiophene unit, and their regio‐regular placement is confirmed by NMR spectroscopy. The thienyl based side‐groups broaden polymer absorption ranges and at the same time lead to uncommon emission properties that are results of light‐induced charge transfer events between the polymer main‐chains and side‐chains. Removal of the silyl groups on one of these rr‐PTV's led to insoluble materials and x‐ray diffraction experiments on the collected solids displayed distinct scattering peaks that are absent from similarly functionalized regio‐random PTV's reported previously, thus suggesting better crystallinity originated from regio‐regularity.

Regio-regular poly(thienylene vinylene)s (rr-PTVs) through acyclic diene metathesis (ADMET) polymerization and the impact of alkyl side-chains on polymer molecular weight and solubility

Poly(thienylene vinylene) (PTV) is one of the prototypical conjugated polymers (CPs) that has received relatively little attention. The insertion of one small double bond between every pair of adjacent thiophene units in PTV structures potentially allow direct functionalization of the thienyl rings, which can fine-tune polymer electronic properties without significantly impact main-chain planarity. However, synthetic methods leading to such tailor-designed PTVs are scarce. In this paper, we report a new synthetic strategy that produces a series of regio-regular (rr) PTVs bearing bromine atoms and different alkyl side-chains on every thiophene unit. The methodology starts with synthesis of well-defined dimeric monomers that lead to rr-PTVs upon ADMET polymerization. The monomers and polymers are fully characterized by NMR and absorption spectroscopy. We found that linear and slightly branched alkyl chains led to precipitation during the polymerization process and thus low apparent molecular weight due to limited polymer solubility, while long-branched and bulky silyl-alkyl ether chains led to PTVs with greater solubility and higher molecular weights.

Design and Synthesis of a New Non‐Fullerene Acceptor for High‐Performance Photomultiplication‐Type Organic Photodiodes

AbstractPhotomultiplication‐type organic photodiodes (PM‐OPDs) rely on acceptor molecules for both charge separation and efficient gain generation. Herein, a new non‐fullerene acceptor is designed and synthesized by introducing thienylenevinylene (TV) groups into the conventional 2,2ʹ‐[[6,6,12,12‐tetrakis(4‐hexylphenyl)‐6,12‐dihydrodithieno[2,3‐d:2ʹ,3ʹ‐dʹ]‐s‐indaceno[1,2‐b:5,6‐bʹ]dithiophene‐2,8‐diyl]bis[methylidyne(3‐oxo‐1H‐indene‐2,1(3H)‐diylidene)]]bis[propanedinitrile] (ITIC) structure. The resulting TV‐ITIC acceptor possesses not only extended π‐conjugation length, which leads to lower energy bandgap as well as deeper lowest unoccupied molecular orbital (LUMO) level, but also enhanced hydrophobic characteristics, owing to the increased volumetric portion of the aliphatic chain, which improves the miscibility with the donor polymer semiconductor, poly(3‐hexylthiophene‐2,5‐diyl) (P3HT). Moreover, pristine TV‐ITIC films consist of intrinsically well‐ordered anisotropic crystallites, which are confirmed by 2D grazing incidence X‐ray diffraction (2D‐GIXD) analysis. All of these photophysical properties are beneficial for efficient exciton separation, electron trapping, and charge injection abilities of PM‐OPDs compared to those obtained with conventional ITIC. Because of such synergetic contributions of TV‐ITIC to the photomultiplication mechanism, the resulting optimized PM‐OPD exhibits a high external quantum efficiency (>74,000%) and a large specific detectivity (>1012 Jones).

Formation of Large Crystalline Domains in a Semiconducting Polymer with Semi-fluorinated Alkyl Side Chains and Application to High-Performance Thin-Film Transistors.

The semi-fluorinated alkyl (SFA) side chain introduced thienylenevinylene (TV)-based p-type polymer, PC12TVC5F7T, was synthesized for use in organic thin-film transistors (OTFTs). Herein, we investigated the influence of SFA side chains on the morphology, molecular orientation, and crystalline structure using a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM), two-dimensional (2D) grazing-incidence wide-angle X-ray scattering (GIWAXS), and density functional theory (DFT) calculations. Interestingly, the incorporation of SFA side chains led to the evolution of plate-like large-sized domains and also strongly intermolecular stacked high crystalline structures. Furthermore, due to the strong interactions between SFA side chains, several (00h) peaks could be observed for PC12TVC5F7T, in spite of their fairly large dihedral angle. As a result, due to the well-developed microstructure of PC12TVC5F7T, the OTFT devices based on it exhibited a high hole mobility of 1.91 cm2 V-1 s-1, which is an outstanding value among the poly(thiophene) derivative polymers. These observations indicate that large-sized domains and strongly intermolecular stacked high crystalline structures, which are beneficial for charge carrier transport, could be attained by the introduction of SFA side chains, further enhancing the performance of the OTFTs.

Highly Ambient-Stable Organic Thin-Film Transistors Fabricated Using Naphthalene Diimide and Thienylene–Vinylene–Thienylene-Based n-Type Polymers with Different Electron-Withdrawing Groups

We designed, synthesized, and characterized a series of naphthalene diimide (NDI)-based polymers with pristine (H)-, fluorine (F)-, chlorine (Cl)-, and cyano (CN)-substituted thienylene–vinylene–th...

Atom-economical Synthesis and Characterization of Poly(oxindolidene thienylene vinylene) Based on Aldol Polycondensation Reaction

It is known that π-conjugated polymers can be easily synthesized using monomers which possess metals or halogen atoms as well as transition-metal catalysts. However, in the polymer materials synthesized by such reactions, small amounts of halogens and transition-metal-catalysts remain, often negatively affecting their optoelectronic device performances. Herein, we report a new polycondensation method based on the aldol condensation reaction utilizing the intramolecular resonance effect of the anionic monomer through π-conjugation. We have designed a novel AB type monomer to synthesize the semiconducting poly(oxindolidene thienylene vinylene) (POTV) using the proposed system. Indeed, the polymerization readily proceeded by adding 5-nitro-2-thiophenecarbaldehyde as an initiator after the α-proton abstraction of the oxindole group by the reaction of the monomer precursor with lithium hexamethylsilazide (LiHMDS)/12-crown-4. As a result, the objective POTV with Mn = 3700 and ÐM = 1.47 could be obtained with a good yield (65%). In addition, an organic field effect transistor (OFET) was based on POTV exhibited p-type characteristics, with a hole mobility of 2.24 × 10−4 cm2 V−1 s−1.

3,4-Ethylenedioxythiophene-Based Isomer-Free Quinoidal Building Block and Conjugated Polymers for Organic Field-Effect Transistors

Since quinoidal molecules have double-bond linkages between aromatic rings, they have many advantages for efficient charge transport resulting from high planarity and extended π-conjugation length. However, they unavoidably generate some isomers, which cause difficulty in purification and characterization. In this study, sulfur–oxygen conformation locking and steric repulsion approach is introduced to manipulate syn- and anti-isomerization of a quinoidal building block (bis-QEDOT). As a result, isomer-free bis-QEDOT is synthesized by introducing the 3,4-ethylenedioxy group, and the geometrical structure of bis-QEDOT is identified by thin-layer chromatography, 1H NMR, and density functional theory calculation. Furthermore, thiophene (T), bithiophene (2T), and thienylene vinylene (TV) as π-conjugated building blocks are polymerized with bis-QEDOT. Due to the quinoid structure, PQEDOT-T, PQEDOT-2T, and PQEDOT-TV show an intensified near-IR absorption and a low band gap around ∼1.16 eV. Grazing incidence wide-angle X-ray diffraction reveals that three quinoidal polymers show in the (h00) diffraction peaks up to third order after thermal annealing at 250 °C, demonstrating high crystallinity of the films. Finally, the electrical properties of the three polymers are investigated as an active layer in organic field-effect transistors showing hole mobilities of 4.3 × 10–2 (PQEDOT-T), 1.8 × 10–2 (PQEDOT-2T), and 7.8 × 10–3 cm2 V–1 s–1 (PQEDOT-TV).

A liquid-crystalline semiconducting polymer based on thienylene–vinylene–thienylene: Enhanced hole mobilities by mesomorphic molecular ordering and thermoplastic shape-deformable characteristics

Liquid-crystalline (LC) π-conjugated polymers are an emerging class of semiconducting materials owing to their promising performance in organic field-effect transistors (OFETs). Little is known, however, about the relationship between LC nature and charge carrier mobility. In this paper, we focus on a thiophene-based p-type semiconducting polymer, PC12TV12T, containing thienylene–vinylene–thienylene (TVT) units, and report a systematic investigation of its thermotropic LC properties, self-organized structures in bulk and thin films, as well as charge transport properties in OFETs. We found that thermal annealing at LC temperatures (99–170 °C) strongly enhanced OFET performance, leading to field-effect hole mobilities as high as 0.37 cm2 V−1 s−1, comparable to that of amorphous silicon. By virtue of its thermoplasticity, the TVT-based polymer can also be processed into fine semiconducting microfibers, which can even function as a p-type active channel for charge transport. This bottom-up technology utilizing the LC nature enables cost-effective and energy-efficient manufacture of optoelectronic devices. A π-conjugated polymer based on thienylene–vinylene–thienylene (TVT) units can form a thermotropic liquid-crystalline (LC) mesophase over a wide temperature range. Thermal annealing at LC temperatures strongly enhanced hole mobilities in organic field-effect transistors (OFETs) owing to improved molecular ordering. Because of its thermoplasticity, the TVT-based π-conjugated polymer can also be processed into semiconducting fine microfibers and serve as a charge transport pathway in microfiber OFETs.

Impact of side-chain extension on physical and electronic properties of cross-conjugated Poly(thienylene vinylene)s (PTVs)

Poly(thienylene vinylene)s (PTVs) are close analogs to the extensively studied polythiophenes and the insertion of one double bond between every two thiophene units along the main-chain of PTV backbone eliminates steric repulsion and potentially allows installment of conjugated side-chains without significantly distorting the main-chain planarity, offering a facile way of fine-tuning the polymer electronic properties through main-chain/side-chain cross-conjugation. We describe here a new methodology that combines acyclic diene metathesis and post-polymerization modification methods for the access of a series of cross-conjugated PTVs bearing aromatic side-chains connected to the main-chains through alkyne spacers. Compared with unfunctionalized PTVs, these cross-conjugated PTVs showed broader absorption ranges, reduced bandgaps, and rarely observed fluorescence. Organic solar cells employing the cross-conjugated PTVs displayed up to double the efficiency improvement over those employing pristine PTVs. For the first time, these PTVs were applied as sensitizers in composites with g-C3N4 for photocatalytic hydrogen production. It was found that the relative energy level positions between the polymers and g-C3N4 and polymer crystallinity likely played decisive roles in determining the hydrogen production efficiencies, which gave us useful guidelines on future optimization of polymer structures and selection of photocatalytic systems.

Cross-conjugated poly(selenylene vinylene)s

Poly(selenylene vinylene) (PSV) is a close analog to the extensively studied poly(thienylene vinylene) (PTV) polymers, and possesses unique properties originating from the larger, more polarizable Se atoms.

High-Crystallinity π-Conjugated Small Molecules Based on Thienylene-Vinylene-Thienylene: Critical Role of Self-Organization in Photovoltaic, Charge-Transport, and Morphological Properties.

Narrow-band-gap small molecules with π-extended backbones are promising donor materials for solution-processed bulk-heterojunction (BHJ) organic solar cells (OSCs). Herein, a series of acceptor-donor-acceptor (A-D-A) photovoltaic small molecules incorporating thienylene-vinylene-thienylene (TVT) as a central D unit and alkyl-substituted rhodanine or 2-(1,1-dicyanomethylene)rhodanine as terminal A units are designed and synthesized. Their physical properties including photoabsorption, electronic energy levels, hole mobility, and morphological characteristics are systematically investigated. Using solvent vapor annealing (SVA), the morphologies of the BHJ photoactive layers composed of these small-molecule donors and a [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) acceptor can be properly modulated. As a result of increased crystallinity of the donors and desired phase segregation between the donors and PC71BM upon rapid SVA treatment, the photovoltaic performances of the resultant OSC devices undergo drastic enhancement. The results reported here indicate that high-efficiency small-molecule OSCs can be achieved through rational design of the TVT-based molecular framework and optimization of the nanoscale phase-segregated morphology via proper SVA treatment.

Effect of Substituents of Thienylene–Vinylene–Thienylene-Based Conjugated Polymer Donors on the Performance of Fullerene and Nonfullerene Solar Cells

Semiconducting polymers consisting of (E)-1,2-di(thiophen-2-yl)ethene (TVT) derivatives and benzo[1,2-b:4,5-b′]dithiophene with conjugated thiophene side chains (BDTT) were designed and synthesized to investigate the effect of fluorine and cyano groups in the 3-position of the thiophene ring in TVT on the photovoltaic properties. The corresponding PBDTT-TVT, PBDTT-FTVT, and PBDTT-CNTVT copolymers containing TVT, difluoro TVT (FTVT), and dicyano TVT (CNTVT), respectively, demonstrated considerable variations in optical, electrochemical, morphological, and charge transporting properties. PBDTT-FTVT showed suitable frontier orbital energy levels, favorable face-on orientation, and a well-mixed and smooth morphology in the blends with 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC) and [6,6]-phenyl-C71-butyric acid methyl ester (PCBM). In contrast, PBDTT-CNTVT showed unfavorable frontier orbital ener...

Ternalization Approach for Tuning Light Absorption and Crystalline Structure of Diketopyrrolopyrrole-Based Polymer Using Bisthiadiazole Unit

Diketopyrrolopyrrole (DPP) and bisthiadiazole (BTDz)-based terpolymers were developed to obtain tunable optical properties and crystalline structures. Using dibromo-compounds of DPP and BTDz with distannylated thienylene vinylene (TV) moieties, high molecular weight polymers (44,100-99,200) with varied BTDz compositions (25, 50, or 75 mol%) were obtained. The introduction of BTDz generated a complementary light absorption band in the short-wavelength region (∼550 nm), while the DPP units created an intramolecular charge transfer band at ∼730 nm. As a result, terpolymers with a deep highest occupied molecular orbital energy of −5.50 eV and narrow bandgap of <1.5 eV were obtained. In addition, the crystal orientation of the DPP-based polymer was changed from edge-on to face-on by copolymerizing with only 25 mol% BTDz units.

Thienylene vinylene dimerization: from solution to self-assembled monolayer on gold.

The electrochemical and spectroelectrochemical studies of thienylene vinylene (TV) derivatives in the immobilized state are compared with the ones obtained in solution. The results highlight the exaltation of the dimerization process onto TV-based self-assembled monolayers, in which the π interaction is maintained even after 75% dilution.

Modulation of Majority Charge Carrier from Hole to Electron by Incorporation of Cyano Groups in Diketopyrrolopyrrole-Based Polymers

A thienylene–vinylene–thienylene (TVT) derivative with cyano groups in the 3- and 3′-positions was synthesized as a building block of semiconducting polymers for high mobility organic field effect transistors (OFETs). (E)-1,2-Di-(3-cyanothiophen-2-yl)ethene (2CNTVT) was copolymerized with diketopyrrolopyrrole (DPP) units via Stille coupling reaction to give 2DPP-2CNTVT and 7DPP-2CNTVT. The properties of these two polymers were compared with those of the corresponding polymers without cyano groups in TVT (2DPP-TVT and 7DPP-TVT). The effects of CN groups and branched alkyl position were found to have a significant influence on the optical, electrochemical, morphological, and charge transporting properties of the polymers. The average hole mobilities of OFETs fabricated with 2DPP-TVT and 7DPP-TVT OFETs were 1.63 and 2.2 cm2 V–1 s–1, respectively, and the average electron mobility for both 2DPP-2CNTVT and 7DPP-2CNTVT OFETs was 1.2 cm2 V–1 s–1.

A Role of Side-Chain Regiochemistry of Thienylene–Vinylene–Thienylene (TVT) in the Transistor Performance of Isomeric Polymers

The π-extended (E)-2-(2-(thiophen-2-yl)-vinyl)thiophene (TVT)-based polymers are an interesting class of semiconducting polymers because of their excellent mobilities and unique film microstructures. Despite these properties, the effect of the side-chain regiochemistry of TVT skeletons on the intrinsic properties of these polymers remains unclear. To investigate this, in this study, hexyl-substituted TVT subunits with a “tail in (TI)” or “tail out (TO)” regiosymmetrical arrangement were first introduced into diketopyrrolopyrrole (DPP)-based copolymer main chains to afford “isomeric” polymers PI and PO, respectively. By combining optical spectroscopy, atomic force microscopy (AFM), and grazing incidence X-ray diffraction (GIXD) data, we quantitatively characterized the aggregation, crystallization, and backbone orientation of both polymer films, which were then correlated to the charge-carrier mobilities. The PI film exhibited a bimodal packing motif comprising a mixture of edge-on and face-on orientations...

Synthesis of low band gap polymers based on pyrrolo[3,2-d:4,5-d′]bisthiazole (PBTz) and thienylenevinylene (TV) for organic thin-film transistors (OTFTs)

New low band gap copolymers P1–P4, based on thienylenevinylene (TV) and pyrrolo[3,2-d:4,5-d′]bisthiazole (PBTz).

Rational Design of High‐Mobility Semicrystalline Conjugated Polymers with Tunable Charge Polarity: Beyond Benzobisthiadiazole‐Based Polymers

High‐mobility semiconducting polymers composed of arylene vinylene and dithiophene‐thiadiazolobenzotriazole (SN) units are developed by three powerful design strategies, namely, backbone engineering, heteroatom substitution, and side‐chain engineering. First, starting from the quaterthiophene‐SN copolymer, a vinylene spacer is inserted into the quaterthiophene unit for constructing highly‐planar backbones. Second, heteroatoms (O and N atoms) are incorporated into the thienylene vinylene moieties to tune the electronic properties and intermolecular interactions. Third, the alkyl side chains are optimized to tune the solubility and self‐assembly properties. As a consequence, a remarkable thin film transistor performance is obtained. The very high hole mobility of 3.22 cm2 V−1 s−1 is achieved for the p‐type polymer, PSNVT‐DTC8, which is the highest value ever reported for the polymers based on the benzobisthiadiazole and its analogs. Moreover, heteroatom substitution efficiently varies the charge polarity of the polymers as in the case of the N atom substituted PSNVTz‐DTC16 displaying n‐type dominant ambipolar properties with the electron mobility of 0.16 cm2 V−1 s−1. Further studies using grazing‐incidence wide‐angle X‐ray scattering and atomic force microscopy have revealed the high crystallinities of the polymer thin films with strong π–π interactions and suitable polymer packing orientations.