Heavily n‑Dopable π‑Conjugated Redox Polymers with Ultrafast Energy Storage Capability

We report here the first successful demonstration of a “π-conjugated redox polymer” simultaneously featuring a π-conjugated backbone and integrated redox sites, which can be stably and reversibly n-doped to a high doping level of 2.0 with significantly enhanced electronic conductivity. The properties of such a heavily n-dopable polymer, poly­{[<i>N</i>,<i>N</i>′-bis­(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl]-<i>alt</i>-5,5′-(2,2′-bithiophene)} (P­(NDI2OD-T2)), were compared <i>vis-à-vis</i> to those of the corresponding backbone-insulated poly­{[<i>N</i>,<i>N</i>′-bis­(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl]-<i>alt</i>-5,5′-[2,2′-(1,2-ethanediyl)­bithiophene]} (P­(NDI2OD-TET)). When evaluated as a charge storage material for rechargeable Li batteries, P­(NDI2OD-T2) delivers 95% of its theoretical capacity at a high rate of 100C (72 s per charge–discharge cycle) under practical measurement conditions as well as 96% capacity retention after 3000 cycles of deep discharge–charge. Electrochemical, impedance, and charge-transport measurements unambiguously demonstrate that the ultrafast electrode kinetics of P­(NDI2OD-T2) are attributed to the high electronic conductivity of the polymer in the heavily n-doped state

Ion Pair p<i>K</i>s of Some Amines: Extension of the Computed Lithium p<i>K</i> Scale

The p<i>K</i> of <i>p</i>-(methylamino)­biphenyl, <b>1</b>, on our Li scale, p<i>K</i>(Li) = 22.09, compared to the cesium scale, p<i>K</i>(Cs) = 28.60. For hexamethyldisilazane, HMDS, p<i>K</i>(Li) = 23.05, p<i>K</i>(Cs) = 29.26. These results are those for the monomers in THF; corrections were made for dimers present in some cases. The p<i>K</i>(Li) of these two amines fit well the previously found correlation with Hartree–Fock calculations at 6-31+g­(d) using RLi coordinated with three dimethyl ethers as a computational model for RLi in THF. The results are also compared with earlier p<i>K</i>(Li)­s reported from equilibria with lithium amides in which aggregation was not considered

On-Surface Solvent-Free Crystal-to-Co-crystal Conversion by Non-Covalent Interactions

Enabling and understanding new methodologies to fabricate molecular assemblies driven by intermolecular interactions is fundamental in chemistry. Such forces can be used to control crystal growth and enable surface-confinement of these materials, which remains challenging. Here we demonstrate for the first time, a solvent-free on-surface crystal-to-co-crystal conversion process driven by halogen bonding (XB). By exposing a polycrystalline organic material, consisting of a XB-acceptor moiety, to the vapors of a complementary XB-donor compound, the corresponding halogen-bonded co-crystals were formed. Furthermore, we demonstrate that this approach can also be utilized for non-crystalline materials to afford surface-confined organic composites. Our stepwise vapor-based approach offers a new strategy for the formation of hybrid supramolecular materials

Annulated Thienyl-Vinylene-Thienyl Building Blocks for π‑Conjugated Copolymers: Ring Dimensions and Isomeric Structure Effects on π‑Conjugation Length and Charge Transport

A series of annulated thienyl-vinylene-thienyl (<b>ATVT</b>) building blocks having varied ring sizes, isomeric structures, and substituents was synthesized and characterized by spectroscopic, electrochemical, quantum chemical, and crystallographic methods. It is found that <b>ATVT</b> ring size and isomeric structure critically affect the planarity, structural rigidity, optical absorption, and redox properties of these new π-units. Various solubilizing substituents can be introduced on the annulated hydrocarbon fragments, preserving the <b>ATVT</b> planarity and redox properties. The corresponding π-conjugated copolymers comprising <b>ATVT</b> units and electron-deficient units were also synthesized and characterized. The solubility, redox properties, and carrier transport behavior of these copolymers also depend remarkably on the annulated ring size and the <b>ATVT</b> unit isomeric structure. One of the copolymers composed of an <b>ATVT</b> with five-membered rings (<b>1</b>), (<i>E</i>)-4,4′,5,5′-tetrahydro-6,6′-bi­(cyclopenta­[<i>b</i>]­thiophenylidene), and a naphthalenediimide (<b>NDI</b>) unit exhibits a broad UV–vis–NIR absorption with an onset beyond 1100 nm both in solution and in the film state, and thin films exhibit n-type semiconducting properties in field-effect transistors. These results are ascribed to the extended main chain π-conjugation length and the low HOMO–LUMO bandgap. Other π-conjugated copolymers containing unit <b>1</b> also exhibit characteristic red-shifted UV–vis–NIR absorption. A diketopyrrolopyrrole-based copolymer with unit <b>1</b> serves as an electron donor material in organic photovoltaic devices, exhibiting broad-range external quantum efficiencies from the UV to beyond 1000 nm

Annulated Thienyl-Vinylene-Thienyl Building Blocks for π‑Conjugated Copolymers: Ring Dimensions and Isomeric Structure Effects on π‑Conjugation Length and Charge Transport

A series of annulated thienyl-vinylene-thienyl (<b>ATVT</b>) building blocks having varied ring sizes, isomeric structures, and substituents was synthesized and characterized by spectroscopic, electrochemical, quantum chemical, and crystallographic methods. It is found that <b>ATVT</b> ring size and isomeric structure critically affect the planarity, structural rigidity, optical absorption, and redox properties of these new π-units. Various solubilizing substituents can be introduced on the annulated hydrocarbon fragments, preserving the <b>ATVT</b> planarity and redox properties. The corresponding π-conjugated copolymers comprising <b>ATVT</b> units and electron-deficient units were also synthesized and characterized. The solubility, redox properties, and carrier transport behavior of these copolymers also depend remarkably on the annulated ring size and the <b>ATVT</b> unit isomeric structure. One of the copolymers composed of an <b>ATVT</b> with five-membered rings (<b>1</b>), (<i>E</i>)-4,4′,5,5′-tetrahydro-6,6′-bi­(cyclopenta­[<i>b</i>]­thiophenylidene), and a naphthalenediimide (<b>NDI</b>) unit exhibits a broad UV–vis–NIR absorption with an onset beyond 1100 nm both in solution and in the film state, and thin films exhibit n-type semiconducting properties in field-effect transistors. These results are ascribed to the extended main chain π-conjugation length and the low HOMO–LUMO bandgap. Other π-conjugated copolymers containing unit <b>1</b> also exhibit characteristic red-shifted UV–vis–NIR absorption. A diketopyrrolopyrrole-based copolymer with unit <b>1</b> serves as an electron donor material in organic photovoltaic devices, exhibiting broad-range external quantum efficiencies from the UV to beyond 1000 nm

Exploratory Combustion Synthesis: Amorphous Indium Yttrium Oxide for Thin-Film Transistors

We report the implementation of amorphous indium yttrium oxide (a-IYO) as a thin-film transistor (TFT) semiconductor. Amorphous and polycrystalline IYO films were grown via a low-temperature solution process utilizing exothermic “combustion” precursors. Precursor transformation and the IYO films were analyzed by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and optical transmission, which reveal efficient conversion to the metal oxide lattice and smooth, transparent films. a-IYO TFTs fabricated with a hybrid nanodielectric exhibit electron mobilities of 7.3 cm² V^–1 s^–1 (<i>T</i>_anneal = 300 °C) and 5.0 cm² V^–1 s^–1 (<i>T</i>_anneal = 250 °C) for 2 V operation

Self-Assembled Metallic Nanowire-Based Vertical Organic Field-Effect Transistor

We report on in situ, self-assembly, solution-processing of metallic (Au/Ag) nanowire-based transparent electrodes integrated to vertical organic field-effect transistors (VOFETs). In the VOFET architecture, the nanowires’ microstructure facilitates current modulation by the gate across the otherwise shielding sandwiched source electrode. We show N-type VOFETs operation with on/off ratio ∼1 × 10⁵ and high current density (>1 mA cm^–2 at <i>V</i>_DS = 5 V). The integration of the device design and the transparent electrode deposition methods offers a potential route for all-solution processing-based, large-area, high-efficiency organic electronics

Annulated Thienyl-Vinylene-Thienyl Building Blocks for π‑Conjugated Copolymers: Ring Dimensions and Isomeric Structure Effects on π‑Conjugation Length and Charge Transport

A series of annulated thienyl-vinylene-thienyl (<b>ATVT</b>) building blocks having varied ring sizes, isomeric structures, and substituents was synthesized and characterized by spectroscopic, electrochemical, quantum chemical, and crystallographic methods. It is found that <b>ATVT</b> ring size and isomeric structure critically affect the planarity, structural rigidity, optical absorption, and redox properties of these new π-units. Various solubilizing substituents can be introduced on the annulated hydrocarbon fragments, preserving the <b>ATVT</b> planarity and redox properties. The corresponding π-conjugated copolymers comprising <b>ATVT</b> units and electron-deficient units were also synthesized and characterized. The solubility, redox properties, and carrier transport behavior of these copolymers also depend remarkably on the annulated ring size and the <b>ATVT</b> unit isomeric structure. One of the copolymers composed of an <b>ATVT</b> with five-membered rings (<b>1</b>), (<i>E</i>)-4,4′,5,5′-tetrahydro-6,6′-bi­(cyclopenta­[<i>b</i>]­thiophenylidene), and a naphthalenediimide (<b>NDI</b>) unit exhibits a broad UV–vis–NIR absorption with an onset beyond 1100 nm both in solution and in the film state, and thin films exhibit n-type semiconducting properties in field-effect transistors. These results are ascribed to the extended main chain π-conjugation length and the low HOMO–LUMO bandgap. Other π-conjugated copolymers containing unit <b>1</b> also exhibit characteristic red-shifted UV–vis–NIR absorption. A diketopyrrolopyrrole-based copolymer with unit <b>1</b> serves as an electron donor material in organic photovoltaic devices, exhibiting broad-range external quantum efficiencies from the UV to beyond 1000 nm

Fine Structural Tuning of Cyanated Dithieno[3,2‑<i>b</i>:2′,3′‑<i>d</i>]silole–Oligothiophene Copolymers: Synthesis, Characterization, and Photovoltaic Response

We report here the synthesis and characterization of a new series of semiconducting polymers based on dithieno­[3,2-<i>b</i>:2′,3′-<i>d</i>]­silole (SiDT) copolymerized with cyanated oligothiophenes (-2T- or -4T-) units. The effect of the fine structural tuning of the thiophene-based spacer on optical, electronic, morphological, and photophysical properties of the resulting polymers is investigated and correlated with the organic photovoltaic (OPV) performance. Bulk heterojunction (BHJ) solar cells, using this class of copolymers as electron donor material, are fabricated, optimized, and fully characterized. As a result of rational structural modifications, PCEs of ∼5% and open-circuit voltages (<i>V</i>_OC) greater than 0.8 V are achieved without the need of additional thermal annealing

Remarkable Order of a High-Performance Polymer

We directly image the rich nanoscale organization of the high performance, <i>n</i>-type polymer poly­{[<i>N</i>,<i>N</i>′-bis­(2-octyldodecyl)-naphthalene-1,4,5,8-bis­(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (P­(NDI2OD-T2)) using a combination of high-resolution transmission electron microscopy and scanning transmission electron microscopy. We demonstrate that it is possible to spatially resolve “face-on” lamella through the 2.4 nm alkyl stacking distance corresponding to the (100) reflection. The lamella locally transition between ordered and disordered states over a length scale on the order of 10 nm; however, the polymer backbones retain long-range correlations over length-scales approaching a micrometer. Moreover, we frequently observe overlapping structure implying a number of layers may exist throughout the thickness of the film (∼20 nm). The results provide a simple picture, a highly ordered lamella nanostructure over nearly the entire film and ordered domains with overlapping layers providing additional interconnectivity, which unifies prior seemingly contradictory conclusions surrounding this remarkable, high-mobility material