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Two-Dimensional Conducting Polymers: Synthesis and Charge Transport
摘要： Current technological advances and prolific endeavors have entrenched two-dimensional conducting polymers as the rapidly emerging interface across a diversity of functional materials for flexible electronics, sensors, ion-exchange membranes, biotechnology, catalysis, energy storage, and conversion. Rational design and fabrication of polymeric nanostructures enriched with well-ordered geometry are appealing and endorse significant impact on their inbuilt electrical, optical, and mechanical properties. In particular, recent interest in controlled hierarchical assembly of monomers/oligomers proved the free-standing sheet-like structures with exotic features of high conductivity and flexibility. Yet, the ongoing research to make nanometer-thick polymers suffers from limitations to access large-area, mechanical stability, and high-range internal ordering. In this perspective, we focus on the radical approaches that highlight confinement-entitled features of two-dimensional polymeric materials correlating to their interface or template-assisted synthesis, structure–property relationship, charge transport properties, and future scopes for relevant practical enactments.
关键词： 2D assembly,self-organization,conjugated polymers,charge transport,interfacial synthesis
更新于2025-09-23 15:22:29
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Initial evaluation of proportional scintillation in liquid Xenon for direct dark matter detection
摘要： The Liquid Xenon Time Projection Chamber (LXeTPC) is often seen as an ideal detector for the direct Dark Matter (DM) search. In such experiments an efficient γ-ray background discrimination is essential. This can be achieved by distinguishing the ionization density, different for γ-rays and Nuclear Recoils. Two quantities are used for this measurement, the direct scintillation light generated by the ionizing event, and the free charges swept away by an electric field before recombination occurs. Present LXe detectors apply the Dual Phase principle, i.e. the charges are extracted into the gas phase and are measured by the proportional light they produce in a strong electric field in the gas. With ever growing dimensions of the detectors it is difficult to meet the tight mechanical tolerances required. Proportional scintillation also occurs in the liquid phase, although at much higher field strengths. Such field strengths can be reached in the 1/r field close to thin wires. All the limitations due to the extraction of electrons into the gas phase are avoided. Since the liquid level has not to be crossed, the design of the detector becomes simpler with many advantages over Dual Phase detectors. Our initial tests clearly show the pulses. They are much shorter, and their length is limited by longitudinal diffusion of the drifting charges. The threshold for proportional light production seems significantly lower, and estimates of the gain are more favorable than previously predicted. We attribute these discrepancies to our improved liquid purity.
关键词： Time projection Chambers (TPC),Dark Matter detectors (WIMPs,multiplication and electroluminescence in rare gases and liquids,ionization,Charge transport,double-phase),axions,etc.),Noble liquid detectors (scintillation
更新于2025-09-23 15:22:29
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Charged solitons in branched conducting polymers
摘要： We consider the dynamics of charged solitons in branched conducting polymers, such as, e.g., trans-polyacetylene. An effective model based on the sine-Gordon equation on metric graphs is used for computing the charge transport and scattering of charge carriers at the polymer branching points. The condition for the ballistic charge carrier transport is revealed.
关键词： metric graphs,charged solitons,charge transport,branched conducting polymers,ballistic transport,sine-Gordon equation
更新于2025-09-23 15:21:21
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Low Frequency Dielectric Relaxation and Charge Transport in Bi<sub>12</sub>TiO<sub>20 </sub>Photorefractive Sillenite Crystals
摘要： Features of processes of a dielectric relaxation and charge transport in photorefractive sillenite crystals Bi12TiO20 at low frequency range are investigated. It was found that the dispersion of dielectric permittivity ε' in crystals Bi12TiO20 is characterized by its growth with lowering frequency and rising temperature. This behaviour may be related to existence of dipole-relaxation polarization mechanism. The frequency dependence of dielectric loss tgδ reveals the existence of low frequency relaxation peaks in the studied temperature range. From the conductivity dependence on the frequency and temperature it was found that conductivity σ increases as frequency increases in the low frequency range. The observed dependence σ(ω)≈Аωs indicates that transport mechanism is due to hopping of carriers via localized electron states. The charge transport is thermally activated process in which activation energy Ea = (0.82±0.03) eV.
关键词： Charge transport,Photorefractive Sillenite crystals,Dielectric relaxation
更新于2025-09-23 15:21:21
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Formation of Occupied and Unoccupied Hybrid Bands at Interfaces between Metals and Organic Donors/Acceptors
摘要： Efficient charge transport in organic semiconductors and at their interfaces with electrodes is crucial for the performance of organic molecule-based electronic devices. Band formation fosters effective transport properties and can be found in organic single crystals of large π-stacking aromatic molecules. However, at molecule/metal interfaces hybrid band formation and band dispersion is a rarely observed phenomenon. Using angle-resolved two-photon photoemission supported by density functional theory calculations we demonstrate such band formation for two different molecule/metal systems, namely tetrathiafulvalene (TTF)/Au(111) and tetrafluoro-tetracyanoquinodimethane (F4TCNQ)/Au(111), in the energy region of occupied as well as unoccupied electronic states. In both cases strong adsorbate/substrate interactions result in formation of interface states due to hybridization between localized molecular states and delocalized metal bands. These interface states exhibit significant dispersions. Our study reveals that hybridization in combination with an extended well-ordered adsorption structure of the π-conjugated organic molecules is a striking concept to receive and experimentally observe band formation at molecule/metal interfaces.
关键词： band formation,organic semiconductors,molecule/metal interfaces,hybridization,charge transport,density functional theory,angle-resolved two-photon photoemission
更新于2025-09-23 15:21:21
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D-??-D molecular semiconductors for perovskite solar cells: the superior role of helical versus planar ??-linker
摘要： Controlling the mode of molecular packing and the size of molecular aggregate are of fundamental importance for high-performance charge transporting materials in next-generation optoelectronic devices. To clarify the peculiar role of helicene as kernal blocks in the exploration of unconventional organic semiconductors, in this work thia[5]helicene (T5H) is duplicately aminated with electron-donating dimethoxydiphenylamine to afford T5H-OMeDPA, which is systematically compared with its perylothiophene (PET) congener (PET-OMeDPA). On the basis of quantum theory of atoms in molecules and energy decomposition analysis of single-crystals, it is suprisingly found that while π-π stacking of planar PET is stronger than that of helical T5H, this desirable effect for charge transport of organic semiconductors is completely lost for donor-π-donor (D-π-D) typed PET-OMeDPA, but is retained for T5H-OMeDPA to a large extent. Consequently, T5H-OMeDPA single-crystal presents an about 5 times higher theoretical hole-mobility than PET-OMeDPA. More critically, the solution-processed racemic glassy film of T5H-OMeDPA displays a 3 times higher hole-mobility in comparison with the PET-OMeDPA counterpart, due to a larger domain of molecular aggregate. With respect to PET-OMeDPA, there is a weaker electronic coupling of helical T5H-OMeDPA with perovskite, leading to a reduced interfacial charge recombination. Due to reduced transport resistance and enhanced recombination resistance, perovskite solar cells with T5H-OMeDPA exhibit a power conversion efficiency of 21.1%, higher than that of 19.8% with PET-OMeDPA and that of 20.6% with spiro-OMeTAD control.
关键词： charge transport,perovskite solar cells,helicene,molecular semiconductors,π-π stacking
更新于2025-09-23 15:21:01
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Systematic Modulation of Charge Transport in Molecular Device through Facile Control of Molecule-Electrode Coupling using Double Self-assembled Monolayers Nanowire Junction
摘要： We report a novel solid-state molecular device structure based on double self-assembled monolayers (D-SAMs) incorporated into the suspended nanowire architecture to form “Au | SAM-1 || SAM-2 | Au” junction. Using commercially available thiol molecules that are devoid of synthetical difficulty, we constructed Au | S-(CH2)6-Ferrocene || SAM-2 | Au junction, with various length and chemical structure of SAM-2 to tune the coupling between ferrocene conductive molecular orbital and electrode of the junction. Combining low noise and wide temperature range measurement, we demonstrated systematically modulated conduction depending on the length and chemical nature of SAM-2. Meanwhile, transport mechanism transition from tunneling to hopping, and the intermediate state accompanied by the current fluctuation due to the coexistence of the hopping and tunneling transport channels, were observed. Considering the versatility of this solid-state D-SAMs in modulating the electrode-molecule interface and electroactive groups, this strategy thus provides a novel facile strategy for tailorable nanoscale charge transport study and functional molecular devices.
关键词： charge transport,molecular device,nanowire junction,self-assembled monolayers,ferrocene
更新于2025-09-23 15:21:01
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Photovoltaic parameters and stability study of HTM-free mixed-cation perovskite solar cells by incorporating additives to absorbing layers
摘要： In this study, quick route-coating is practiced to substitute methyl ammonium (MA) cation with formamidinium (FA) at different ratios. Through optimizing the MA:FA ratio, a maximum power conversion efficiency (PCE) of 8.31% is achieved for holes transporting material-free MA0.8FA0.2PbI3 mixed PSCs with the JSC of 19.02 mA/cm2, VOC of 0.859 V and FF of 50.88%. Then, to improve the performance, stability and carrier transport dynamic, various additives (PVA, PVP, PEG and EC) are incorporated into the perovskite layer. The treatment of perovskites with additives has proved to cause significant changes in the surface roughness, charge accumulation, charge transport, charge transport resistance, photovoltaic performance and cell stability. PCE of the PSCs mixed with PVA, PVP, EC and PEG optimally reaches 12.76%, 11.28%, 10.38% and 8.92%, respectively. Among the additives, EC and PVP provide better stability owing to the excellent interaction between the functional group of the additives and the perovskite. Surface modification and charge transport also occur better with those two additives.
关键词： Charge transport,Perovskite solar cells,Stability,Additives,Photovoltaic performance
更新于2025-09-23 15:21:01
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Exploiting ternary blends for improved photostability in high efficiency organic solar cells
摘要： Ternary organic solar cells based on polymer donor and nonfullerene acceptors (NFAs) are delivering high power conversion efficiencies (PCE). Now, further improvement needs to be directed to enhance the operational lifetime of organic photovoltaics. Here, we selected three NFAs with different electron affinities and structural properties and found that the most crystalline third component, O-IDTBR, is selectively miscible within the acceptor phase. This reduced trap-assisted recombination and delivered a PCE of 16.6% and a fill factor of 0.76, compared to PM6:Y6 binary devices (15.2% PCE). Charge transport and recombination analyses revealed that O-IDTBR acts as a charge relay for improved charge transfer of both donor and acceptor materials leading to a more ordered transport. We find that minimizing traps formation in ternary devices deactivates light-induced traps upon full sun illumination (AM1.5G). As a result, ternary devices do not show any PCE drop in 225h, in comparison to binary cells which lose more than 60% of their initial performances.
关键词： photostability,nonfullerene acceptors,ternary organic solar cells,power conversion efficiency,charge transport
更新于2025-09-23 15:21:01
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Phase Distribution and Carrier Dynamics in Multiple-Ring Aromatic Spacers-Based Two-Dimensional Ruddlesden-Popper Perovskite Solar Cells
摘要： Two-dimensional (2D) perovskites with natural multi-quantum-well structure have been reported to offer better stability compared to 3D perovskites. However, the understanding of the exciton separation and transport mechanism in 2D perovskite as well as developing more efficient organic spacers remain considerable challenges as the 2D perovskite exhibit large exciton binding energy due to quantum confinement. Here, a class of multiple-ring aromatic ammoniums, 1-naphthalenemethylammonium (NpMA) and 9-anthracenemethylammonium (AnMA), were developed as spacers for 2D Ruddlesden-Popper (RP) perovskite solar cells (PSCs). In addition to significantly enhanced stability, the device based on (NpMA)2(MA)n-1PbnI3n+1 (average n = 4) exhibits a champion efficiency of 17.25% and a high open circuit voltage of 1.24 V. The outstanding photovoltaic performance could be ascribed to the ultrafast exciton migration (within 7 ps) from 2D phases to 3D-like phases, which were confirmed by charge carrier dynamics results, leading to efficient exciton separation, charge transportation and collection. This work facilitates understanding the working mechanism of 2D PSCs deeply and offers an efficient way to further boosting their efficiency and stability by developing multiple-ring aromatic spacers.
关键词： perovskite solar cell,organic spacer,phase distribution,charge transport,two-dimensional
更新于2025-09-23 15:21:01