Electron correlation effects on polarons recombination in coupled polymer chains

The recombination dynamics of singlet and triplet oppositely charged polarons under the influence of electron–electron (e–e) interactions in coupled polymer chains are investigated using a multi-configurational time-dependent Hartree–Fock (MCTDHF) method. During recombination processes, singlet and triplet intrachain excitons are important products. By calculating the yields of the singlet and triplet intrachain excitons as a function of the on-site and long-range e–e interactions, it is found that the yields of the singlet and triplet intrachain excitons both decrease with increasing on-site e–e interactions. On the other hand, as the long-range e–e interactions increase, the yields of singlet intrachain excitons initially increase and then maintain a constant value, while the yields of the triplet intrachain excitons decrease. Our results show that the long-range e–e interaction is of fundamental importance and improves the luminescence efficiency in coupled polymer chains. Finally, the influence of the polymer chain length on the yields of singlet and triplet intrachain excitons is discussed.     

Toward the Optimized Spintronic Response of Sn‐Doped IrO2 Thin Films

Amorphous and polycrystalline Sn‐doped IrO₂ thin films, Ir_1‐xSn_xO₂, are grown for the first time. Their electrical response and strength of the spin–orbit coupling are studied in order to better understand and tailor its performance as spin current detector material. These experiments prove that the resistivity of IrO₂ can be tuned over several orders of magnitude by controlling the doping content in both the amorphous and the polycrystalline state. In addition, growing amorphous samples increase the resistivity, thus improving the spin current to charge current conversion. As far as the spin–orbit coupling is concerned, the system not only remains in a strong spin–orbit coupling regime but it seems to undergo a slight enhancement in the amorphous state as well as in the Sn‐doped samples.     

Performance evaluation of a tactile and kinesthetic finger feedback system for teleoperation

Teleoperation during a catastrophic event requires an interface that can perform under frequently changing circumstances caused by unpredictable and dangerous conditions. Thus, teleoperation interfaces are under active development to provide both visual and haptic feedback to the fingers. However, studies of teleoperation systems with finger haptic feedback based on force profiles are difficult to conduct because of interface limitations. Therefore, in this paper, we introduce an intuitive teleoperation interface, an anthropomorphic teleoperated robot, and a hand-wearable force-feedback system that provides various feedbacks to the fingers. We combined these systems to compare and evaluated the performance of tactile and kinesthetic finger feedback using two experiments: maintaining appropriate grip force for variably fragile objects and following a force trajectory that changed in real time. Ten subjects participated in the experiments. The results were analyzed using repeated measures analysis of variance. Feedback factors differed significantly. Provision of force feedback to the user’s finger was most effective in both teleoperation experiments.     

Development of compatible wet-clean stripper for integration of CoWP metal cap in Cu/low-k interconnects

Implementation of CoWP metal caps into Cu/low-k integration schemes requires a wet stripper that not only gives efficient cleaning but also has good compatibility to CoWP and low-k dielectrics. This paper describes a novel non-fluoride CoWP compatible stripper, developed based on a systematic study of the effect of stripper components, i.e. solvent, corrosion inhibitor, and stripper pH. Electrochemical methods were used to characterize galvanic corrosion of the CoWP/Cu couple and to estimate CoWP etch rate. Our studies showed that a traditional fluoride stripper caused severe damage to CoWP capping layer. The new stripper achieved a good balance between cleaning efficiency and compatibility to CoWP and low-k dielectrics, and demonstrated significant advantages in electrical properties over the traditional fluoride stripper.     

Disordered Topography Mediates Filopodial Extension and Morphology of Cells on Stiff Materials

In cell–material interactions, cells use filopodia to sense external biochemical and mechanical cues, and subsequently dictate their survival. In an effort toward understanding how disordered topography of stiff materials influences filopodial recognition, diamond films with grain sizes varying from nano‐ to micrometers are fabricated for the investigation of osteoblast filopodial extension. Interestingly, straight filopodia with pronounced cell–substrate adhesion are observed on a nanocrystalline diamond (NCD) region, whereas filopodia on a microcrystalline diamond (MCD) surface only adhere to, and get deflected by, large diamond grains. More importantly, filopodia on NCD keep propagating with a constant velocity, whereas the same process takes place in a slow and intermittent manner on MCD. A theoretical model is also developed and it suggests that the contact between the disordered topography and the filopodial tip plays a key role in altering filopodial growth dynamics. In particular, it is predicted that large surface asperities can block the movement of the filopodial tip, delay its extension, and cause bending of the structure, in quantitative agreement with experimental observations. These findings reveal previously underappreciated effects of random, stiff topographies on the response of cells, and hence can provide new insights for the design of future implant biomaterials.     

Balancing Intermolecular Interactions between Acceptors and Donor/Acceptor for Efficient Organic Photovoltaics

Promoted by uninterrupted materials and device innovation, organic solar cells have achieved impressive development. However, the complicated intermolecular interactions inside active layers are less understood. Herein, the intermolecular interactions are studied from the dual perspectives of acceptor/acceptor (A/A) and donor/acceptor (D/A), and how these interactions synergistically control the final efficiencies. Three small molecular acceptors (SMAs) are designed with different end-caps, which manipulate the crystallinity and electrostatic potential (ESP) distributions of acceptors, and accordingly, the A/A and D/A intermolecular interactions. The results show that SMA LA17 with low A/A interactions exhibits inferior performance around 12%, owing to its strong D/A interaction with donor PM6, which shapes too miscible morphology and increases charge recombination. Instead, LA16 with strong A/A interactions and moderate D/A interactions delivers improved bulk-heterojunction (BHJ) networks, and therefore, enhances charge transport and diminishes geminate or trap-assisted charge recombination. Consequently, PM6:LA16 records the competitive efficiency of up to 13.74% among the three systems. Therefore, this study deepens the synergistic or balancing effect of the D/A and A/A interactions on BHJ blends for efficient organic solar cells.     

A Molecular Brush Approach to Enhance Quantum Yield and Suppress Nonspecific Interactions of Conjugated Polyelectrolyte for Targeted Far‐Red/Near‐Infrared Fluorescence Cell Imaging

A red‐fluorescent conjugated polyelectrolyte (CPE, P2 ) is grafted with dense poly(ethylene glycol) (PEG) chains via click chemistry and subsequently modified with folic acid to form a molecular brush based cellular probe ( P4 ). P4 self‐assembles into a core–shell nanostructure in aqueous medium with an average size of 130 nm measured by laser light scattering. As compared to P2 , P4 possesses not only a substantially higher quantum yield (11%), but also reduced nonspecific interactions with biomolecules in aqueous medium due to the shielding effect of PEG. In conjunction with its high photostability and low cytotoxicity, utilization of P4 as a far‐red/near‐infrared cellular probe allows for effective visualization and discrimination of MCF‐7 cancer cells from NIH‐3T3 normal cells in a high contrast, selective, and nonviral manner. This study thus demonstrates a flexible molecular brush approach to overcome the intrinsic drawbacks of CPEs for advanced bioimaging applications.     

A Bridge between Ceramics Electrolyte and Interface Layer to Fast Li+ Transfer for Low Interface Impedance Solid-State Batteries

Solid-state batteries (SSBs) are regarded as next generation advanced energy storage technology to provide higher safety and energy density. However, a practical application is plagued by large interfacial resistance, owing to solid-solid interface contact between ceramics electrolytes and Li anode. Introducing polymer-based coating between electrolytes and Li anode is a feasible strategy to solve this issue. Unfortunately, current polymer is hard to achieve intimate contact at the atomic scale and lacks of a bridge to transfer Li⁺ quickly between electrolytes and polymer coating. This gives rise to sluggish Li⁺ transfer dynamics, huge interface impedance and greatly limits the effectiveness of this strategy. Herein, Poly(lithium 4-styrenesulfonate)(PLSS) is introduced between Li_6.5La₃Zr_1.5Ta_0.5O₁₂ (LLZTO) electrolyte and Li anode. The theories and experiments prove the existence of strong coordinating interaction between  SO₃Li in PLSS and atoms on LLZTO surface. This interaction structures a bridge to migrate Li⁺ fast across LLZTO/PLSS interface and hence interface impedance is as low as 9 Ω cm². Moreover, the electron-blocking feature of PLSS can prevent electrons from tunneling the LLZTO/PLSS interface and combining with Li⁺ to form dendrite within LLZTO. PLSS-base cells show improved long-life cycling for 4700 h at 0.1 mA cm⁻² at room temperature.     

Dispersion-Enabled Symmetry Switching of Photonic Angular-Momentum Coupling

Photonic spin-orbit interactions describe the interactions between spin angular momentum and orbital angular momentum of photons, which play essential roles in subwavelength optics. However, the influence of frequency dispersion on photonic angular-momentum coupling is rarely studied. Here, by elaborately designing the contribution of the geometric phase and waveguide propagation phase, the dispersion-enabled symmetry switching of photonic angular-momentum coupling is experimentally demonstrated. This notion may induce many exotic phenomena and be found in enormous applications, such as the spin-Hall effect, optical calculation, and wavelength division multiplexing systems. As a proof-of-concept demonstration, two metadevices, a multi-channel vectorial vortex beam generator and a phase-only hologram, are applied to experimentally display optical double convolution, which may offer additional degrees of freedom to accelerate computing and a miniaturization configuration for optical convolution without collimation operation. These results may provide a new opportunity for complex vector optical field manipulation and calculation, optical information coding, light-matter interaction manipulation, and optical communication.