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Highlights • Vertical silicon, diamond and graphene structures for supercapacitor applications. • Electrochemical synthesis of conducting polymers onto 3D nanostructures. • Electrochemical performances of supercapacitor devices using ionic liquids. • Multi-hierarchized 3D nanostructures (PEDOT-D@SiNWs) showed the best performances. • Supercapacitive graphene and diamond nanostructures for new perspectives using ILs. Abstract The potential of electroactive conducting polymers (ECPs), as innovative pseudocapacitive materials, has recently emerged as a promising strategy to design new and advanced concepts in the field of electrochemical energy storage devices. From this point of view, the synergistic effect produced between high electroactivity ECPs (faradaic behaviour) and large active surface 3D nanostructured materials (electrochemical double layer behaviour) in terms of their high specific capacitance, high energy and power density as well as long lifetime, has awakened an enormous interest in the domain of (micro)-supercapacitors. Accordingly, in this work, we have originally analyzed the conformal electrochemical deposition of three different π-conjugated heterocyclic polymers [poly(3,4-ethylenedioxythiophene, polypyrrole and polyaniline] onto various vertically-oriented 3D nanoarchitectures, as for example silicon nanowires (SiNWs), diamond nanowires (DiNWs) or graphene nanosheets (GNs) among others. Next, the resulting as-grown hybrid materials were evaluated as attractive electrodes in symmetric supercapacitors (sandwich configuration) in presence of organic, aqueous, aprotic and protic ionic liquid (IL) electrolytes respectively. An exhaustive characterization of their corresponding electrochemical performances was investigated according to our previously reported works, confirming the remarkable cycling stability of ECPs in ILs. In addition, a detailed state-of-the-art dealing with other types of (micro)-supercapacitors in the literature was reported to corroborate the great impact of such devices to pave the way towards the elaboration of next generation high performance supercapacitors in the coming years. [ABSTRACT FROM AUTHOR]

N-Ethylcarbazole (NECZ) or carbazole (CZ) and bithiophene (BT) have been used as a mixture of monomers for the formation of electrodeposited polymer and copolymer films on platinum electrode. When beginning with a NECZ–BT mixture, the peak intensity resulting from the composite film cycling decreases with increasing initial NECZ proportion until that proportion reaches 40%. For higher NECZ proportions, no deposit could be obtained. Infrared spectra of the deposits show the presence of the characteristic bands of both monomer units in the material. In the case of CZ–BT mixtures, the electrochemical behaviours of the composite films are close to those displayed by the homopolymers, i.e. polybithiophene or dicarbazyle, containing respectively low and high proportions of CZ. Furthermore, infrared and ultraviolet-visible studies of deposits obtained for various CZ proportions yield spectra that vary according to monomer proportion. [Copyright &y& Elsevier]

Bis[5-(2,2′-bithienyl)]tetrazine has been synthesized and polymerized electrochemically. This is the first example of an electroactive polymer containing a tetrazine moiety in the main chain. In addition, reduction of the tetrazine ring has been shown to be possible in the films. [Copyright &y& Elsevier]

Using Si as anode materials for Li-ion batteries remain challenging due to its morphological evolution and SEI modification upon cycling. The present work aims at developing a composite consisting of carbon-coated Si nanoparticles (Si@C NPs) intimately embedded in a three-dimensional (3D) graphene hydrogel (GHG) architecture to stabilize Si inside LiB electrodes. Instead of simply mixing both components, the novelty of the synthesis procedure lies in the in situ hydrothermal process, which was shown to successfully yield graphene oxide reduction, 3D graphene assembly production, and homogeneous distribution of Si@C NPs in the GHG matrix. Electrochemical characterizations in half-cells, on electrodes not containing additional conductive additive, revealed the importance of the protective C shell to achieve high specific capacity (up to 2200 mAh.g−1), along with good stability (200 cycles with an average Ceff > 99%). These performances are far superior to that of electrodes made with non-C-coated Si NPs or prepared by mixing both components. These observations highlight the synergetic effects of C shell on Si NPs, and of the single-step in situ preparation that enables the yield of a Si@C-GHG hybrid composite with physicochemical, structural, and morphological properties promoting sample conductivity and Li-ion diffusion pathways. [ABSTRACT FROM AUTHOR]

This work deals with electroactive conducting polymers (ECPs) used as a complementary component on purely capacitive silicon nanowires protected by a 3 nm alumina layer. Accordingly, in this work, we use a fast and simple deposition method to create a pseudocapacitive material based on the electropolymerization in aqueous micellar media (SDS and SDBS 0.01 M) of hydroxymethyl-EDOT (EDOT-OH) onto 3 nm alumina-coated silicon nanowires (Al3@SiNWs). The composite material displays remarkable capacitive behavior with a specific capacitance of 4.75 mF·cm−2 at a current density of 19 µA·cm−2 in aqueous Na2SO4 electrolyte. [ABSTRACT FROM AUTHOR]

Developing flexible solid-state micro-supercapacitors with large potential window is crucial for many technologies. The present study focuses on the synthesis and elaboration of quasi-solid-state (QSS) electrolytes with an electrochemical stability greater than 3.0 V based on functionalized polysiloxane. Their electrochemical behavior was studied with silicon nanowires electrodes. The polysiloxane was functionalized with both ammonium and cross-linkable functions. The nanostructured electrodes were impregnated with a mixture of ionic liquid and functionalized polysiloxane. The crosslinking of the polymer electrolyte was then performed by thermal curing directly within the nanostructured electrodes. The quasi-solid system exhibits very high stability upon galvanostatic cycling i.e. during 100 000 cycles with a cell potential of 3.0 V only a capacitance loss of 2.10−5% per cycle was registered. The performance of this QSS with safe electrolyte is remarkable. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon nanowires (SiNWs) were successfully coated by uniform, adherent and homogenous ultra-thin crystalline diamond films through microwave enhanced chemical vapor deposition (MWCVD). The as-grown functionalized nanowires were employed as electrodes in a symmetric micro-supercapacitor (MSC) using a protic ionic liquid electrolyte [triethylammonium bis(trifluoromethylsulfonyl)imide; Et 3 NH TFSI]. The electrochemical performance of the device delivered a specific capacitance of 1.5 mF cm − 2 and a power density of 25 mW cm − 2 using an enlarged cell voltage of 4 V. Furthermore, a remarkable cycling stability was evaluated after 1 · 10 6 galvanostatic cycles at a high current density of 10 mA cm − 2 with an excellent capacitive behavior. These results confirm that diamond-coated SiNW micro-supercapacitors exhibit very promising performances dealing with MSCs based on CVD-grown SiNWs. [ABSTRACT FROM AUTHOR]

Silicon nanotrees (SiNTrs) have been grown by Chemical Vapor Deposition (CVD) via gold catalysis and a three steps process: trunks and branches growth are separated by a new gold catalyst deposition. The influence of growth conditions and the second gold catalyst deposition method on SiNTrs morphology are investigated. SiNTrs based electrodes show a capacitive behavior and better capacitance than the corresponding silicon nanowires (SiNWs) electrode. Electrode capacitance is increased up to 900 µF cm-2, i.e. 150 fold higher than for bulk silicon. Micro-supercapacitors with SiNTrs electrodes have a remarkable stability (only 1.2% loses of their initial capacitance after more than one million cycles). The use of an ionic liquid based electrolyte leads to a high maximum power density (around 225 mW cm-2) which is competitive with Onion Like Carbon based micro-supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract: The potential of silicon nanowires (SiNWs) as electrode material for large-voltage window micro-supercapacitors has been investigated. An ionic liquid electrolyte (EMI-TFSI) has been used in order to prevent the previously reported etching of silicon electrodes. Electrochemical oxidation of silicon surface at high anodic potentials leads to an extended operating voltage range (up to 4V) and slightly enhanced specific capacitance of silicon electrodes. The ability of SiNW electrodes to operate at high frequency was demonstrated and a promising specific power of 472μWcm−2 was obtained. [Copyright &y& Elsevier]

New alternating copolymers derived from thieno[3,4-c]pyrrole-4,6-dione (TPD) and 2,7-carbazole moieties havebeen synthesized by Suzuki cross-coupling reaction and characterized.These polymers combine interesting properties such as good solubilityand excellent thermal and air stability. The present studies indicatethat the combination of TPD and 2,7-carbazole building blocks canbe a very effective way to lower the HOMO energy level and ultimatelyto enhance the Vocof polymer solar cells.The Vocreported here (up to 1.07 V) isone of the highest observed for polymer:[60]PCBM bulk heterojunctiondevices, and preliminary results on the photovoltaic devices (powerconversion efficiencies up to 1.8%) indicate that performance couldprobably be improved by increasing the molecular weights and by fine-tuningthe electronic properties and the morphology. [ABSTRACT FROM AUTHOR]

Dielectric materials have been used for decades for energy applications where their insulation and polarizability properties are critical. In the energy storage field, most material scientists envision high-k dielectric layers in contact with an active material only as an insulating passivation layer. In microelectronics, this concept has been modified with the study of dielectrics at nanoscale level revealing interesting properties scarcely known by other fields. We propose to reconsider the vision of high-k dielectric materials for energy at nanoscale specifically. Based on microelectronic measurement techniques and nanometric control of dielectric thickness by Atomic Layer Deposition (ALD), an ultra-thin pinhole-free alumina (Al 2 O 3) layer on a silicon nanowire (SiNW) is shown to display thickness dependent tunneling electrical conduction. This result brings a new light on this material class in the energy field and allows original approaches toward achieving scientific leaps. As an illustrative application, a silicon based micro-supercapacitor (MSC) protected by 3 nm of alumina dielectric layer exhibits Electrical Double Layer Capacitance (EDLC) by means of tunneling current in aqueous electrolyte, an unprecedented result for this material, with outstanding lifetime capacity retaining 99% of its initial capacitance after 2 million cycles. Extended to multiple energy materials, such method could lead to notable progress. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A conjugated oligomer containing central bi-ethylenedioxythiophene (BEDOT) unit and two terminal anil-substituted carbazole units has been characterized by cyclic voltammetry and spectroelectrochemical methods (UV–vis–NIR and Raman). It shows two oxidation waves at −0.01V and +0.24V (versus Fc/Fc+), which can be ascribed to two successive oxidative dopings of the molecule. The molecule is transmissive sharp yellow when fully reduced, transmissive green upon oxidation up to the end of the first oxidative process, and dark blue upon full oxidation. UV–vis–NIR and Raman spectroelectrochemical investigations show that the colour changes within the potential of the first oxidation wave are associated with the oxidation of both carbazole and ethylenedioxythiophene subunits whereas the electrochromic effect in the potential range of the second oxidation wave involves predominantly the oxidation of the ethylenedioxythiophene subunits. [Copyright &y& Elsevier]

Abstract: Highly doped (both n and p-type dopings) silicon nanowires (SiNWs) have been deposited via Chemical Vapor Deposition and investigated as electrode materials for micro-capacitor in a standard organic based electrolyte. Silicon nanostructuration enables to increase areal capacitance. Double layer capacitance values up to 46μF·cm−2 have been measured. Micro capacitors based on two SiNWs electrodes exhibit an excellent cycling ability and power density as high as 1.6mW·cm−2. [Copyright &y& Elsevier]

Building of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO2@silicon nanowires (MnO2@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl)imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO2@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2 V and exhibits a high areal capacitance of 13 mFcm−2. The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO2 nanoflakes are responsible for the remarkable performance of these MnO2@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors. [ABSTRACT FROM AUTHOR]

Geminate recombination of bound polaron pairs at the donor/acceptor interface is one of the major loss mechanisms in organic bulk heterojunction solar cells. One way to overcome Coulomb attraction between opposite charge carriers and to achieve their full dissociation is the introduction of high dielectric permittivity materials such as nanoparticles of narrow band gap semiconductors. We selected CuInS2 nanocrystals of 7.4 nm size, which present intermediate energy levels with respect to poly(3-hexylthiophene) (P3HT) and Phenyl-C61-butyric acid methyl ester (PCBM). Efficient charge transfer from P3HT to nanocrystals takes place as evidenced by light-induced electron spin resonance. Charge transfer between nanocrystals and PCBM only occurs after replacing bulky dodecanethiol (DDT) surface ligands with shorter 1,2-ethylhexanethiol (EHT) ligands. Solar cells containing in the active layer a ternary blend of P3HT:PCBM:CuInS2-EHT nanocrystals in 1:1:0.5 mass ratio show strongly improved short circuit current density and a higher fill factor with respect to the P3HT:PCBM reference device. Complementary measurements of the absorption properties, external quantum efficiency and charge carrier mobility indicate that enhanced charge separation in the ternary blend is at the origin of the observed behavior. The same trend is observed for blends using the glassy polymer poly(triarylamine) (PTAA). [ABSTRACT FROM AUTHOR]