Original Article in 2017

We report a new anode material that has multifunction of both an anode and a hole injection layer (HIL) as a single layer. Our anode has easy work function tunability up to 5.8 eV and thus makes ohmic contact without any HIL. We applied our anodes to simplified organic light-emitting diodes, resulting in high efficiency (62% ph el⁻¹ for single and 88% ph el⁻¹ for tandem). Our anode showed a similar tendency in simplified perovskite light-emitting diodes. We also demonstrated large-area flexible lightings using our anodes. Our results provide a significant step toward the next generation of high-performance simplified light-emitting diodes.

The bimetallic Au@Rh core–shell nanodendrites with ultrathin Rh nanoplate shells show the light-enhanced catalytic activity for the hydrogen generation reaction from aqueous hydrazine solution.

Micron-thick highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) films are fabricated using a novel self-inhibited polymerization (SIP) approach. The newly adopted inhibitor-free heavy oxidative solutions containing weakly basic anions (WBAs) such as dodecylbenzenesulfonate (DBSA) enables the spin-coating of thick and homogeneous oxidant layer, and meanwhile effectively inhibits both the crystallization of the oxidant and the H⁺ formation throughout the polymerization process.

To profit of the breadth of multifunctional properties that double perovskites (A₂BB’O₆) exhibit, it is required to have high control on cation ordering of the B-site. We show that by growing thin films under minor in-plane strain along the (111) direction, cation ordering can be stimulated as a result of the formation of two differently sized and shaped B-sites. Such an approach enables the study of many new ordered double perovskites which have never been made before.

Despite great efforts that have focused on anticancer adjuvants, drug resistance in cancer therapy is still a challenging problem. Conventional spherical nanoprobes are unable to effectively destroy the cellular structure in therapy which means the gastric tumor has a high risk of drug resistance. Herein we developed a novel flower-like targeting Fe₃O₄@Au-HPG-Glc nanoprobe that can rotate along the central axis of the core and substantially destroy the tumor cells by damaging the tumor cells under an alternating magnetic field. The successful application of novel shape-dependent therapy strategy would potentially reduce drug resistance problems of gastric tumors.

One of the main criteria for realising new, interface-related heterostructure behaviours is the ability to control the atomic and electronic properties on an atomic level which typically requires creating epitaxially matched superlattices. Here, we demonstrate that single-crystalline, misfit-dislocation free interfaces between tetragonal Cu-doped FeSe and trigonal Bi₂Te₃ symmetry lattices with very large lattice mismatch (19%) can be realised due to the van der Waals-like bonding between the FeSe and Bi₂Te₃. The atomically resolved interface structure analysis and DFT calculations show that the Se and Te atomic columns are relaxed, so the overall strain is less than 10% and the energy cost associated with such displacements is less than 0.01 eV, which is significantly lower than the thermal energy at room temperature (0.0257 eV).

Dual-ion doping: Through theoretical and experimental methods, we determined that dual-doped TiO₂ has a much higher electron conductivity than that of single-doped TiO₂, and more Pt occupies the defect sites of dual-doped TiO₂. Pt on this dual-doped support is almost three times more active than Pt on single-doped TiO₂ and is more stable than Pt on carbon.

We demonstrated experimental and theoretical approaches to obtain a full picture of the mixed-anion effects for LiNi_0.5Mn_1.5O_4−xF_x cathode materials. The fluorine anion reduced the activation barrier for lithium (Li)-ion hopping along the most energetically preferable 8a-16c-8a route, enhancing the C-rate capability. Simultaneously, the coordination bond of the linear F⁻–Mn³⁺–F⁻ (Mn@2F diagonal) arrangement increased the oxidation potential to 5.1 V (vs Li⁺/Li). This hampered full extraction of Li⁺ from the spinel lattice, which was triggered by the oxidation of Mn³⁺ below the cutoff voltage (3.5–4.8 V (vs Li⁺/Li)), leading to a capacity loss.

We report the discovery of novel metastable boron allotropes, called hex-B_ν, using the crystal structure search method. First-principles calculations reveal that hex-B_ν shows not only dynamical, mechanical stability but also structural flexibility under high pressures and high temperatures. We suggest a new pressure-induced transition pathway from α-B₁₂ to γ-B₂₈ under extreme conditions, in which our discovered allotropes can act as intermediate phases. This work provides a possible solution to the long-standing fundamental question on the phase transition mechanism between boron allotropes.

A photothermally foldable soft bimorph was prepared by dry transfer of poly(3,4-ethylenedioxythiophene)s (PEDOT) onto poly(dimethylsiloxane) film. The reversible folding nature of the soft bimorph was programmable to convert the two-dimensional (2D) array of bimorph into complex three-dimensional (3D) architectures such as Venus flytrap under light. These 3D structures were returned reversibly to the original unfolded 2D structures under dark. The Venus flytrap could perform a task to snap and move an object within few second of near-infrared exposure. A localized heat pocket was generated inside the folding structure due to the large photothermal effect of PEDOT.

Over 8% efficient ultrathin kesterite Cu₂ZnSnS₄ (CZTS) solar cells have been developed by interface reaction route controlling and self-organized nanopattern at the back contact. An ultrathin dielectric Al₂O₃ intermediate layer is inserted into the Mo/CZTS interface to inhibit the detrimental interfacial reaction between CZTS and Mo, and then turns into a self-organized nanopatterning with opening for electrical contact. The typical issues of phase segregation and voids at the back contact region therefore can be addressed, which reduces back contact recombination and improves the device performance. A 7.6% efficiency world record for 1 cm² CZTS solar cells also has been achieved by this interface modification.

Piezostrain-enabled magnetization switching in magnetic/piezoelectric heterostructures consists of multiple coupled kinetic processes that have rarely been considered together, thus an accurate computational analysis on the switching speed has remained outstanding. Here a computational approach is developed to accurately analyze the speed of such piezostrain-enabled magnetization switching by linking local elastodynamics in the piezoelectric to local magnetization dynamics in the magnet. For example, the approach is utilized to analyze the speed of a recently proposed scheme of piezostrain-enabled 180° perpendicular magnetization switching, where the overall switching time is shown to be below 10 ns in a model CoFeB/Pb(Zr,Ti)O₃ heterostructure.

Having a well aligned monodomain is critical to performing fundamental studies on liquid crystals as well as exploiting them for technological applications. Unlike conventional nematics, lyotropic chromonic liquid crystals are notoriously hard to align. Here, we report on the homogeneous planar alignment of Sunset Yellow in a flat rectangular capillary. Counterintuitively, the in-plane director aligns perpendicular to the long axis of the rectangular capillary. We rationalize the evolution of this configuration from a metastable twisted configuration by considering the coupling of the curvature of the edges of the rectangle to the Frank free energy via the saddle-splay contribution.

We experimentally demonstrate that the spin-wave propagation in the hard-axis direction of an epitaxial Fe waveguide with a cubic anisotropy shows an enhanced spin-wave signal by improving spin-wave amplitude as well as group velocity and attenuation length. Schematic illustrations of a, easy-easy case (both directions of the magnetization and spin-wave propagation are in the easy axis) and b, hard-hard case (both directions of the magnetization and spin-wave propagation are in the hard axis). Magnetic-field dependences of spin-wave amplitude for c, easy-easy case and d, hard-hard case. e, Spin-wave attenuation length and f, group velocity as a function of the magnetic field.

The dc-ngCA-silk hydrogel is a highly protective biocatalytic matrix fabricated through bioinspired photoinduced chemical and dehydration-mediated physical dual-crosslinking of silk fibroin and carbonic anhydrase. The fabricated silk hydrogel exhibited significantly high toughness, resiliency and stability with good catalytic activity, which enabled its successful use as a robust biocatalyst for CO₂ sequestration.

A flash-evaporation printing technology is developed that employs freestanding carbon nanotubes as a flash evaporator. The target materials precoated on the flash evaporator are printed onto substrates by gas-phase transportation. This methodology offers a printable solution for hybrid perovskite thin films, and can also be used to print patterns and a wide variety of materials on large panels.

A full-color, solid-state, volumetric display based on second harmonic generation in a transparent glass-ceramic (GC) containing second-order optical nonlinear crystals is described. The device uses infrared femtosecond laser beams that focus inside the GC to address red, green and blue voxels. Three-dimensional images are drawn by scanning the point of focus of the lasers inside of the material. The prototype device is demonstrated using conventional focusing optics and mechanical scanners, and the image is bright enough to be seen in ambient room lighting conditions.

Initially formed amorphous GeTe layer crystallizes during growth by molecular beam epitaxy, as critical film thickness is reached. A remarkable change in bonding mechanism and improvement in atomic order are observed, in striking contrast to conventional lattice-matched epitaxial systems. Supported by density function theory calculations, resonant bonding is shown to be less favorable in an ultrathin GeTe film.

Formulation of carboxymethyl cellulose (CMC) and chitosan (CHI) hydrogel containing curcumin-loaded microcapsules (Cur-M) are developed for intratumoral injection. The Cur-M-loaded CMC and CHI (CCH) formulation forms a Cur-M-loaded CCH depot after mixing via electrostatic interactions between the anionic CMC and cationic CHI. The Cur-M-loaded CCH depot lead to greater inhibition of tumor growth.

In a typical thermal explosion process, a single-phase CuFeS₂ is obtained in a very short time and the thermoelectric performance of the fully condensed bulk samples is better than that of the samples synthesized by the traditional methods. The presence of phase boundaries in the CuFeS_2−x has an effect on the transport properties: phase boundaries scatter low-frequency phonons and reduce the thermal conductivity of a composite structure. Moreover, large differences in the carrier concentration in CuFeS₂ and Cu_1.1Fe_1.1S₂ drive a redistribution of electrons in the composite and lead to an enhancement in the electronic transport properties.