Electronic structure, transport, and collective effects in molecular layered systems

• Torsten Hahn,
• Tim Ludwig,
• Carsten Timm and
• Jens Kortus

Beilstein J. Nanotechnol. 2017, 8, 2094–2105, doi:10.3762/bjnano.8.209

• tetracyanoquinodimethane (TCNQ) [5][6]. At interfaces between different organic materials interesting physical phenomena appear, in most cases due to (partial) charge transfer between the materials. One example is the formation of a two-dimensional metallic interface between insulating organic crystals [7][8]. Other

• effects are metal-insulator transitions or superconductivity which were reported for organic charge-transfer crystals realized by a combination of strongly electron-accepting and strongly electron-donating molecules [9][10]. Recently, a heterostructure of manganese phthalocyanine (MnPc) and structurally

• similar fluorinated copper phthalocyanine (F16CoPc), has demonstrated the occurrence of hybridization [11]. It was proved that a local charge transfer which affects only the transition-metal centers changes the charge state of the transition metal and is directly related to a change of its magnetic moment

Adsorbate-driven cooling of carbene-based molecular junctions

• Giuseppe Foti and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 2060–2068, doi:10.3762/bjnano.8.206

• of the CA junction. Electron donation from the carbene to the Au tip is reduced in the presence of the NH2 unit, resulting in NHC spectral features at slightly higher energies in the C than in the CA junctions. Notice that the behavior in terms of charge transfer and redistribution of this NH2

Intercalation of Si between MoS₂ layers

• Rik van Bremen,
• Qirong Yao,
• Soumya Banerjee,
• Deniz Cakir,
• Nuri Oncel and
• Harold J. W. Zandvliet

Beilstein J. Nanotechnol. 2017, 8, 1952–1960, doi:10.3762/bjnano.8.196

• graphene layers synthesized on metal substrates [59][60][61]. The driving force for intercalation is charge transfer between the intercalated atoms and the layered material [62][63] or thermodynamic stabilization [61][62]. The mechanism of intercalation was found to occur through cracks and wrinkles in the

• occurred. It is very likely that the observed shift is attributed to a change in the position of the Fermi level. It has been shown that the deposition of MoS2 on a SiO2 substrate with interface impurities leads to a charge transfer from the MoS2 surface to the defect states and, thus, to the formation of

Coexistence of strongly buckled germanene phases on Al(111)

• Weimin Wang and
• Roger I. G. Uhrberg

Beilstein J. Nanotechnol. 2017, 8, 1946–1951, doi:10.3762/bjnano.8.195

• within 0.01 eV/Å. Simulated STM images were generated from local density of states according to the Tersoff–Hamann approach [17]. The charge transfer was calculated by the Bader scheme within VASP. (a) LEED pattern obtained at an electron energy of 55 eV from Al(111) with 0.6 ML of Ge deposited at a rate

Freestanding graphene/MnO₂ cathodes for Li-ion batteries

• Şeyma Özcan,
• Aslıhan Güler,
• Tugrul Cetinkaya,
• Mehmet O. Guler and
• Hatem Akbulut

Beilstein J. Nanotechnol. 2017, 8, 1932–1938, doi:10.3762/bjnano.8.193

• coin cells. The initial specific capacity of graphene/α-, β-, and γ-MnO2 freestanding cathodes was found to be 321 mAhg−1, 198 mAhg−1, and 251 mAhg−1, respectively. Finally, the graphene/α-MnO2 cathode displayed the best cycling performance due to the low charge transfer resistance and higher

• the cell, electrochemical impedance spectroscopy (EIS) measurements were performed and results are shown in Figure 5. The width of the Nyquist curves indicates the charge transfer resistance (Rct) of the graphene/α-MnO2, graphene/β-MnO2 and graphene/γ-MnO2 cathodes [30]. As seen from Figure 5, the

Carbon nano-onions as fluorescent on/off modulated nanoprobes for diagnostics

• Stefania Lettieri,
• Marta d’Amora,
• Adalberto Camisasca,
• Alberto Diaspro and
• Silvia Giordani

Beilstein J. Nanotechnol. 2017, 8, 1878–1888, doi:10.3762/bjnano.8.188

• transfer (PET) and internal charge transfer (ICT) donor characteristics of the dimethylamino functionalities attached to a π-extended distyryl-substituted boron dipyrromethene (BODIPY) dye [23][24] to obtain a pH-sensitive nano-probe. Hence, CNOs grafted with BODIPY 3 molecules (fluo-CNOs) led to the

• Figure 1, Table 1). We observed that the on/off process is fast and reversible making this dye suitable for pH-dependent probes. Interestingly, this BODIPY sample also exhibited an internal charge transfer (ICT) characteristic resulting in a hypsochromic shift of the dye emission upon nitrogen

Application of visible-light photosensitization to form alkyl-radical-derived thin films on gold

• Rashanique D. Quarels,
• Xianglin Zhai,
• Neepa Kuruppu,
• Jenny K. Hedlund,
• Ashley A. Ellsworth,
• Amy V. Walker,
• Jayne C. Garno and
• Justin R. Ragains

Beilstein J. Nanotechnol. 2017, 8, 1863–1877, doi:10.3762/bjnano.8.187

• (bpy)3]2+ (1) results in a long-lived (τ = 1100 ns) [41], oxidizing metal-to-ligand charge transfer excited state [Ru(bpy)3]2+* (2, E1/2(M*/M-) = +0.77 V, SCE) [41] that accepts an electron from benzyl nicotinamide (BNAH, 3, E1/2 = +0.76 V, SCE) [41] to generate the strongly-reducing [Ru(bpy)3]+ (5

• solutions of phthalimide ester and BNAH results in the formation of radicals albeit with a dramatic reduction in efficiency compared to the same reactions performed in the presence of [Ru(bpy)3]2+ [37]. The mechanism of such processes may involve the intermediacy of charge transfer complexes between

Structural model of silicene-like nanoribbons on a Pb-reconstructed Si(111) surface

• Agnieszka Stępniak-Dybala and
• Mariusz Krawiec

Beilstein J. Nanotechnol. 2017, 8, 1836–1843, doi:10.3762/bjnano.8.185

• growing on the bare surface move Pb atoms, which form the dense phase in between the NRs. The stability of Si NRs is achieved by passivation of the bare Si(111) surface by Pb atoms, which in turn lowers the surface energy. The main process behind the energy lowering is the charge transfer from Pb to Si

Non-intuitive clustering of 9,10-phenanthrenequinone on Au(111)

• Ryan D. Brown,
• Rebecca C. Quardokus,
• Natalie A. Wasio,
• Jacob P. Petersen,
• Angela M. Silski,
• Steven A. Corcelli and
• S. Alex Kandel

Beilstein J. Nanotechnol. 2017, 8, 1801–1807, doi:10.3762/bjnano.8.181

• molecule so that it is oriented toward the center. This is not an energetically favorable configuration from an electrostatic standpoint. While in some cases weak dipoles on coinage metals can direct self-assembly [31], a combination of charge transfer and screening of in-plane adsorbate dipoles can result

Adsorption and diffusion characteristics of lithium on hydrogenated α- and β-silicene

• Fadil Iyikanat,
• Ali Kandemir,
• Cihan Bacaksiz and
• Hasan Sahin

Beilstein J. Nanotechnol. 2017, 8, 1742–1748, doi:10.3762/bjnano.8.175

• surface, the amount of charge transfer and energy barriers are given in Table 2. As shown in Figure 2a, four sites of 6Si, 2H, 2HT and 3H are considered as different binding sites for H-α-Si. Our calculations reveal that the most favorable site is 6Si, with the Si–Li bond length of 2.70 Å. In this binding

Three-in-one approach towards efficient organic dye-sensitized solar cells: aggregation suppression, panchromatic absorption and resonance energy transfer

• Jayita Patwari,
• Samim Sardar,
• Bo Liu,
• Peter Lemmens and
• Samir Kumar Pal

Beilstein J. Nanotechnol. 2017, 8, 1705–1713, doi:10.3762/bjnano.8.171

• extinction coefficient (ε) of the metal-to-ligand charge transfer (MLCT) band, a poor absorption in the near-infrared (NIR) range of the solar light and the toxicity are well-documented limitations of these Ru photosensitizers [12]. As an alternative to Ru dyes, less toxic and less expensive organic dyes are

• (Figure 1b) and the absorption spectra of SQ2 in ethanol (Figure 1c), it can be correlated that the highest intensity peak appearing at 651 nm corresponds to π–π* charge-transfer (CT) transitions. A lower intensity peak at the blue end (604 nm) of the spectra is a notable signature of dye aggregation [27

Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study

• İlknur Gergin,
• Ezgi Ismar and
• A. Sezai Sarac

Beilstein J. Nanotechnol. 2017, 8, 1616–1628, doi:10.3762/bjnano.8.161

• analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at

• ohmic resistance of the solution, Rct represents the charge-transfer resistance between nanofiber electrodes and electrolyte interface and Qdl (constant phase element (CPE)) is the double-layer CPE, a frequency-dependent element. The Nyquist plot in Figure 6a consists of a semicircle related to the

• electron-transfer process. The charge-transfer resistance (Rct) can be calculated from measuring the diameter of the semicircle. According to the Bode phase plot in Figure 6b, the phase angle of the sample was 10° around 80 Hz. In the Bode magnitude plot, the absolute values of impedance are plotted as a

Charge transfer from and to manganese phthalocyanine: bulk materials and interfaces

• Florian Rückerl,
• Daniel Waas,
• Bernd Büchner,
• Martin Knupfer,
• Dietrich R. T. Zahn,
• Francisc Haidu,
• Torsten Hahn and
• Jens Kortus

Beilstein J. Nanotechnol. 2017, 8, 1601–1615, doi:10.3762/bjnano.8.160

• large electron affinity. These can be exploited to prepare particular compounds and interfaces with appropriate partners, which are characterized by a charge transfer from or to MnPc. We summarize recent spectroscopic and theoretical results that have been achieved in this regard. Keywords: charge

• -metal phthalocyanine to date. These exceptional properties of MnPc render it possible that this molecule can undergo charge-transfer reactions of either kind, i.e., it can be oxidized or reduced by suitable reaction partners. This can be utilized to synthesize new compounds with potentially interesting

• properties. In this contribution we present a summary of recent results in regard of charge transfer compounds, or interfaces characterized by charge transfer, which all are based on MnPc. Materials and methodology This article covers charge-transfer reactions of manganese phthalocyanine with the alkali

Two-dimensional carbon-based nanocomposites for photocatalytic energy generation and environmental remediation applications

• Suneel Kumar,
• Ashish Kumar,
• Ashish Bahuguna,
• Vipul Sharma and
• Venkata Krishnan

Beilstein J. Nanotechnol. 2017, 8, 1571–1600, doi:10.3762/bjnano.8.159

• charge transfer and better catalytic dispersion to enhance the photocatalytic activity. The 2D carbon-based nanomaterials combine several of the above-mentioned advantages of both 2D and carbon-based materials, and have shown great prospects as catalysts for various applications. As this is currently an

• investigated in detail by various research groups. Hence, a new class of photocatalysts with significantly suppressed charge recombination and fast interfacial charge transfer have been developed using these materials with extraordinary H2 evolution capability. Yeh et al. [107] demonstrated graphite oxide as a

• sites for H2 evolution, increasing interfacial charge transfer and reducing the recombination probability of photogenerated electron–hole pairs [116]. However, the high cost of noble metals limits their use as cocatalysts on a large scale. Graphene has been demonstrated to be one of the best

Formation of ferromagnetic molecular thin films from blends by annealing

• Peter Robaschik,
• Ye Ma,
• Salahud Din and
• Sandrine Heutz

Beilstein J. Nanotechnol. 2017, 8, 1469–1475, doi:10.3762/bjnano.8.146

• 2120 cm−1, respectively. This finding is in contrast to the peak at 2228 cm−1 for the neutral TCNQ [22] and suggests charge transfer (CT) from the Mn ion of the phthalocyanines to the TCNQ molecules forming Mn3+ and TCNQ−. Similar CT was previously observed for MnPc/F4TCNQ films by Rückerl and

Spin-chemistry concepts for spintronics scientists

• Konstantin L. Ivanov,
• Alexander Wagenpfahl,
• Carsten Deibel and
• Jörg Matysik

Beilstein J. Nanotechnol. 2017, 8, 1427–1445, doi:10.3762/bjnano.8.143

• negative polaron on the acceptor molecules with the positive polaron remaining on the donor molecules, is called the charge transfer state (CTS) or charge transfer complex. They have been reported to show the emission–absorption signatures in transient EPR as expected for SCRP [32]. The free charge carrier

• bipolarons, electron–hole (polaron) pairs (or charge transfer excitons), but also polarons interacting with triplets, as well as triplet–exciton pairs. The bipolaron model [83] can explain a positive magnetoresistance in energetically disordered systems, such as a conjugated polymer film. A mobile polaron is

• involving particles with higher spin, e.g., due to the radical–triplet pair mechanism [117][118]. CIDEP effects have already been observed in materials, which are used for OPV: Behrends et al. [32] and Kobori et al. [119] have detected antiphase EPR lines of photo-induced charge transfer complexes, i.e., of

Adsorption and electronic properties of pentacene on thin dielectric decoupling layers

• Sebastian Koslowski,
• Daniel Rosenblatt,
• Alexander Kabakchiev,
• Klaus Kuhnke,
• Klaus Kern and
• Uta Schlickum

Beilstein J. Nanotechnol. 2017, 8, 1388–1395, doi:10.3762/bjnano.8.140

• [1][2] but furthermore to probe its electronic properties [3]. Aromatic molecules deposited onto a metal surface are known to interact through their π-orbitals via van der Waals interactions with the free electron gas at the metal surface [4]. This can lead to a charge-transfer process with or

Fabrication of hierarchically porous TiO₂ nanofibers by microemulsion electrospinning and their application as anode material for lithium-ion batteries

• Jin Zhang,
• Yibing Cai,
• Xuebin Hou,
• Xiaofei Song,
• Pengfei Lv,
• Huimin Zhou and
• Qufu Wei

Beilstein J. Nanotechnol. 2017, 8, 1297–1306, doi:10.3762/bjnano.8.131

• fresh cell are presented in Figure S2 (Supporting Information File 1). The plots for the two samples were similar, consisting of a compressed semicircle and a straight line. The semicircles in the high-frequency range represents the charge-transfer resistance (Rct) and the straight line in the low

• -frequency region represents the diffusion and accumulation process of lithium ions in the electrode [1][29][39]. As can be seen from Figure S2 (Supporting Information File 1), the charge–transfer resistance of sample A2 was about 235 Ω, whereas the charge–transfer resistance of solid TiO2 nanofibers was

• about 425 Ω. Herein, the lower charge–transfer resistance of sample A2 can be ascribed to the hierarchically porous structures of sample A2 facilitating charge transfer at the electrolyte–electrode interfaces [40][41][42] (Figure S2, Supporting Information File 1). Table 1 compares the electrochemical

Charge transport in organic nanocrystal diodes based on rolled-up robust nanomembrane contacts

• Vineeth Kumar Bandari,
• Lakshmi Varadharajan,
• Longqian Xu,
• Abdur Rehman Jalil,
• Mirunalini Devarajulu,
• Pablo F. Siles,
• Feng Zhu and
• Oliver G. Schmidt

Beilstein J. Nanotechnol. 2017, 8, 1277–1282, doi:10.3762/bjnano.8.129

• the charge transport properties of the crystalline nanopyramids, an electrical characterization is performed by measuring the current–voltage (I–V) characteristics. As shown in Figure 2a, the strong charge transfer (CT) between VOPc and F16CuPc causes the heterojunction nanopyramids with double

• the organic nanocrystals. These conclusions prove that with the assistance of the charge transfer effect, the soft yet robust contacts generated from rolled-up nanotechnology provide an efficient route for fabricating reliable organic nanocrystal electronic and spintronic devices. (a) Schematic

Adsorption characteristics of Er₃N@C₈₀on W(110) and Au(111) studied via scanning tunneling microscopy and spectroscopy

• Sebastian Schimmel,
• Zhixiang Sun,
• Danny Baumann,
• Denis Krylov,
• Nataliya Samoylova,
• Alexey Popov,
• Bernd Büchner and
• Christian Hess

Beilstein J. Nanotechnol. 2017, 8, 1127–1134, doi:10.3762/bjnano.8.114

• probably accompanied with charge transfer. Therefore the bonding character is conjectured to exceed the strength of van der Waals interaction. Topographic image (U = 2 V; I = 0.5 nA) of Er3N@C80 on W(110). The molecules appear as bright round structures on the straight monoatomic steps of W(110). The

Ultrasmall magnetic field-effect and sign reversal in transistors based on donor/acceptor systems

• Thomas Reichert and
• Tobat P. I. Saragi

Beilstein J. Nanotechnol. 2017, 8, 1104–1114, doi:10.3762/bjnano.8.112

• donor 2,2',7,7'-tetrakis-(N,N-di-p-methylphenylamino)-9,9'-spirobifluorene (Spiro-TTB) and the electron acceptor 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile (HAT-CN). Intermolecular charge transfer between Spiro-TTB and HAT-CN results in a high intrinsic charge carrier density in the coevaporated

• transistors is the charge-transfer complex molecule, which this system has already shown magnetoresistive effects in organic diodes [17]. In a previous study we presented the first magnetoresistive effects in transistor structures based on a coevaporated (50:50) thin film materials system consisting of 2,2

• does not significantly influence the magnetoresistance, but it strongly depends on the drain voltage Vd. These trends consolidate the conclusions drawn from the electrical characterization, showing a relatively gate-independent transport behaviour [18]. Due to the charge transfer between the HOMO of

ZnO nanoparticles sensitized by CuInZn_xS_2+x quantum dots as highly efficient solar light driven photocatalysts

• Florian Donat,
• Serge Corbel,
• Halima Alem,
• Steve Pontvianne,
• Lavinia Balan,
• Ghouti Medjahdi and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2017, 8, 1080–1093, doi:10.3762/bjnano.8.110

• metal cations in their highest oxidation state do not scavenge electrons (Fe3+ + e− → Fe2+) – contrary to results observed with many TiO2-based photocatalysts [49]. We suppose that this result originates from the heterojunction built between the ZnO and ZCIS materials, which improves charge transfer

• •−, electron and hole scavengers and (b) influence of 1O2 scavengers on the photocatalytic activity of the ZnO/ZCIS composite. The black line corresponds to the experiment conducted without a scavenger. Schematic illustration of the charge transfer process and of the ROS production in the ZnO/ZCIS

The integration of graphene into microelectronic devices

• Guenther Ruhl,
• Sebastian Wittmann,
• Matthias Koenig and
• Daniel Neumaier

Beilstein J. Nanotechnol. 2017, 8, 1056–1064, doi:10.3762/bjnano.8.107

• control limit is in the range of 1010 to 1011 atoms·cm−1, depending on the metal type and technology). They also are influencing the graphene properties by charge-transfer doping [40][41]. The second main contamination source, polymer residues, typically originates in the transfer process from

• 25,000–140,000 cm2·V−1·s−1 for h-BN [44]. Besides the formation of chemical bonds, mainly two mechanisms describe the graphene–substrate interactions, charge-transfer doping and the introduction of strain on the nanoscale. Also, the surface functionalization, e.g., of SiO2 with hexamethyldisilazane (HMDS

• -micrometers. Metal contacts can interact with graphene in different ways [52], as shown in Figure 6. Metals physisorbed on graphene cause charge-transfer-induced doping of the graphene sheet because of the difference in work function values [53]. Metals chemisorbed on graphene are open a band gap in graphene

CVD transfer-free graphene for sensing applications

• Chiara Schiattarella,
• Sten Vollebregt,
• Tiziana Polichetti,
• Brigida Alfano,
• Ettore Massera,
• Maria Lucia Miglietta,
• Girolamo Di Francia and
• Pasqualina Maria Sarro

Beilstein J. Nanotechnol. 2017, 8, 1015–1022, doi:10.3762/bjnano.8.102

• molecules via the virtual charge-transfer amount resulting from the interaction between graphene and analyte molecules, Δq. Hence, the effective number of analyte-induced charge carriers NS onto the devices surface can be expressed as where is the number of analyte molecules adsorbed on the surface of the

• sensing film. A charge transfer of −0.19e for NO2 and 0.02e for NH3 has been assumed, according to the theoretical results found by Zhang et al. on NO2 and NH3 adsorption on pristine graphene [32]. This choice has been made conforming to the results of the morphological characterizations, which attest a

High photocatalytic activity of Fe₂O₃/TiO₂ nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid

• Shu Chin Lee,
• Hendrik O. Lintang and
• Leny Yuliati

Beilstein J. Nanotechnol. 2017, 8, 915–926, doi:10.3762/bjnano.8.93

• and TiO2 nanoparticles that improved charge transfer and suppressed electron–hole recombination. A further investigation on the role of the active species on Fe2O3/TiO2 confirmed that the crucial active species were both holes and superoxide radicals. The Fe2O3(0.5)/TiO2 sample also showed good

• prepared by photodeposition for the degradation of 2,4-D were discussed. In addition to identifying the charge transfer capability of the Fe2O3/TiO2 catalyst for improved photocatalytic activity, the role of the active species on the Fe2O3/TiO2 nanocomposites prepared by the photodeposition method was

• the charge transfer of O2−→Ti4+ and electron excitation from the valence band (VB) to the conduction band (CB) [7][20][21]. Both the heat treatment and addition of Fe species did not affect the light absorption of the TiO2 (NT) in the UV and visible region. Owing to the low loading of Fe, there was no