The hybrid nature and soft lattice of organolead halide perovskites render their structural changes and optical properties susceptible to external driving forces such as temperature and pressure, remarkably different from conventional semiconductors. Here, we investigate the pressure-induced optical response of a typical two-dimensional perovskite crystal, phenylethylamine lead iodide. At a moderate pressure within 3.5 GPa, its photoluminescence red-shifts continuously, exhibiting an ultrabroad energy tunability range up to 320 meV in the visible spectrum, with quantum yield remaining nearly constant. First-principles calculations suggest that an out-of-plane quasi-uniaxial compression occurs under a hydrostatic pressure, while the energy is absorbed by the reversible and elastic tilting of the benzene rings within the long-chain ligands. This anisotropic structural deformation effectively modulates the quantum confinement effect by 250 meV via barrier height lowering. The broad tunability within a relatively low pressure range will expand optoelectronic applications to a new paradigm with pressure as a tuning knob.

3D interconnected MnMoO 4 nanosheet arrays with abundant open spaces and ordered arrangements deposited on nickel foam (NF@MnMoO 4 ) are fabricated by a mild one-step hydrothermal method. As an integrated binder-free electrode for supercapacitors, the optimized NF@MnMoO 4 electrode exhibits a superhigh specific capacitance of 4609 F g −1 (640 mAh g −1 ) at a current density of 1 A g −1 , remarkable rate capability (2800 F g −1 (388.89 mAh g −1 ) even at a current density as high as 20 A g −1 ), and outstanding cycling stability (92.4% of the initial specific capacitance after 20,000 cycles). The fabricated NF@MnMoO 4 //AC asymmetric supercapacitors (ASCs) with excellent cycling performance and high Coulombic efficiency achieve an ultrahigh energy density of 107.38 Wh kg −1 at a power density of 801.34 W kg −1 (72.18 Wh kg −1 at a power density of 3987.85 W kg −1 ). As the practical application, the self-charging power packs of commercial solar cells and NF@MnMoO 4 //AC ASCs are demonstrated to power an LED without extra recharging by other devices, indicating their promising applications in self-power energy-harvesting storage systems.

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A novel method was developed to prepare zinc blende structure CdS: Co diluted magnetic semiconductor nanocrystals. The prepared samples display ferromagnetic behavior with a crystal size of about 3-4 nm. First-principle calculations show the phenomenon of ferromagnetism in CdS:Co nanocrystals arising not only from the Co atoms, but also from the Cd vacancies, with Co atoms being the major contributor. The introduction of Co atoms into CdS significantly reduces the formation energy of Cd vacancies, producing a lot of vacancies which enhance the ferromagnetism of the samples as a whole.

Element doping is an effective method to improve the specific capacity and ion transfer rate of binary metal compounds. In this study, Cu-doped Ni–Co-based electrode materials were synthesized by a hydrothermal process and subsequent annealing treatment. The experimental results show that the nanocone-like Cu-doped Ni–Co carbonate hydroxides (Ni–Co–Cu CH) with high mass loading and the Cu-doped Ni–Co oxide (Ni–Co–Cu oxide) electrode with abundant oxygen defects achieve high area specific capacities of 6.31 F/cm2 and 6.54 F/cm2 at 3 A/g, respectively, which are about 2.5 times larger than the area specific capacity of the undoped nanorod-like Ni–Co precursor electrode (2.51 F/cm2 at 3 A/g). The quasi-solid-state asymmetric supercapacitors (ASCs) Ni–Co–Cu CH//AC and Ni–Co–Cu oxide//AC also achieved high energy densities of 36.9 Wh/kg and 42.1 Wh/kg at power densities of 374.2 W/kg and 374.9 W/kg, respectively, which can light up a red light emitting didode for ∼8 min and ∼11 min, respectively. Cu doping not only changes the morphology and defect state of a Ni–Co bimetallic compound electrode but also improves its electricity conduction and electrochemical performance. This strategy has important reference significance for the preparation of excellent performance supercapacitor energy storage materials in the future.