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Phenethylammonium iodide and its derivatives have been used to passivate the surface traps of metal halide perovskites films to increase the efficiency of solar cells, but their non-conductive nature harms the hole transfer from the perovskite to hole transport layer (HTL). Here, we prepared a novel solution containing 4-methoxyphenethylammonium iodide (CH3O-PEAI) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) to address effectively the above issue. CH3O-PEAI passivates the uncoordinated Pb2+ ions of the perovskite film surface. As an electron acceptor, F4-TCNQ can attract electrons from the valence band of the perovskite film. The energy difference between the valence band maximum and the Fermi level of the perovskite is decreased from 1.37 to 1.23 eV, and thus an upward band bending is formed at the perovskite film surface, which facilitates the hole transport from the perovskite to the HTL, and inhibits reverse electron transport. Consequently, the power conversion efficiency of the perovskite solar cells is increased to 21.57%. [ABSTRACT FROM AUTHOR]

The utilization of plasmonic Ag nanoparticles for harvesting solar energy to drive photocatalysis has attracted much attention. However, short lifetimes of plasmon derived charge carriers, poor chemical stability and easy-aggregation of Ag nanoparticles restrict their direct usage as photocatalysts. In this study, we report, for the first time, the fabrication of Ag nanoparticles fully coated with ultrathin layers of N, O-doped carbon, which were assembled to form a three-level hierarchical structure, i.e. a ginkgo-leaf-like structure (Ag@N,O-C GLLS). Due to the vital role of the N, O-doped carbon layer, the Ag@N/O-C GLLS exhibits excellent mass-normalized rate of H2 production and recycle stability. Our experimental results and theoretical calculation have indicated that the highly improved photocatalytic H2 evolution rate of the Ag@N/O-C GLLS should be attributed to the prolonged lifetimes of hot charge carriers by the full coating of the N,O-C layer, which provide a direct electron transfer path between Ag nanoparticles and the carbon layer. [ABSTRACT FROM AUTHOR]

Fiber supercapacitors (FSCs) have great application potential in future smart textiles and portable and wearable electronics because of their flexibility, tiny volume and wearability. Their main limitation, however, is the low energy density when compared with batteries, which seriously restricts their practical application. How to enhance their energy densities while retaining their high power densities is a critical challenge for fiber-shaped supercapacitor development. Here, we first fabricated three-dimensional CNT sponge (3DCS) by a facile electrochemical activation and freeze-drying method and then synthesized 3DCS/polyaniline nanocomposite fibers by in situ electro-polymerization. Through a rational nanoscale electrode engineering design, the resultant fibers show a specific capacitance as high as 242.9 F cm−1 in 1 M H2SO4. Furthermore, a fiber-shaped asymmetric supercapacitor (FASC) was assembled using 3DCS/P as the positive electrode and 3DCS as the negative electrode. After optimization, the FASC delivers a high energy density of 30.92 μW h cm−2, which is about 2 times higher than that of the highest reported previously, and maintains a maximum power density (1.78 mW cm−2) more than two orders of magnitude higher than those of micro-batteries and an outstanding mechanical stability with 90.2% specific capacitance retained after 1000 bending cycles. In view of the excellent electrochemical characteristics and the simple manufacturing of the highly conductive and flexible 3DCS/P, it offers new opportunities for designing long-life wearable FSCs with high energy density and high power density. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive interface electronic band structure was proposed for improving the capacitance of nano-architectured Ni(OH)2 by introducing a TiO2 embedding layer at the ZnO/Ni(OH)2 interface. A stair-like band alignment was designed to reduce the electron interface transport barrier and induce efficient electron-injection through the interface to the reaction region when it is charging. Consequently, the activation energy of reduction dropped, which further brought about a decreased equilibrium potential (Eeq) depending on the Butler–Volmer model of electrode kinetics. As expected, a superior capacitance of 1981 F g−1 at 2 A g−1 was triggered. After that, this advanced electrode was assembled in an asymmetric cell with a ZnO@Fe2O3 based negative electrode; the as-fabricated device delivered a high energy density of 52.2 W h kg−1 at a power density of 1.3 kW kg−1 within the voltage range of 0–1.6 V as well as a good cycling performance (96.6% capacity retention after 5000 cycles). These features demonstrate that suitable interface engineering may open up new opportunities in the development of high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Fiber-shaped supercapacitors (FSCs) have attracted significant interest owing to their unique advantages of small size, light weight, high flexibility, and capability of being integrated into wearable electronics and smart textiles. Their main limitation, however, is their low energy density when compared with batteries. Here a fiber-shaped asymmetric supercapacitor (FASC) with high energy density has been developed successfully using CNT@ZnO-NWs@MnO2 fibers as the positive electrode and CNT fibers as the negative electrode. Due to the high capacitances and excellent rate performances of CNT@ZnO-NWs@MnO2 fibers and CNT fibers, such an asymmetric cell exhibits superior electrochemical performances. An optimized FASC can be cycled reversibly in the voltage range of 0–1.8 V, and exhibits a maximum energy density of 13.25 μW h cm−2, which is much higher than those reported for fiber-shaped supercapacitors. Owing to the rational structure design, the all-solid-state FASCs demonstrate excellent mechanical and electrochemical stability. Over 1000 bending cycles, 96.7% of the initial capacitance can still be retained. [ABSTRACT FROM AUTHOR]

A self-powered photodetector was fabricated by taking advantage of the band bending at the ZnO/electrolyte interface. And a 48% performance enhancement was achieved with the introduction of 0.15% compressive strain due to the generation of piezopolarization charges. This result could be extended to other solid–liquid reactions, such as photoelectrochemical or photocatalytic processes. [ABSTRACT FROM AUTHOR]

A self-powered Schottky-type ultraviolet photodetector with Al–Pt interdigitated electrodes has been fabricated based on selectively grown ZnO nanowire arrays. At zero bias, the fabricated photodetector exhibited high sensitivity and excellent selectivity to UV light illumination with a fast response time of 81 ms. By tuning the Schottky barrier height through the thermally induced variation of the interface chemisorbed oxygen, an ultrahigh sensitivity of 3.1 × 104 was achieved at 340 K without an external power source, which was 82% higher than that obtained at room temperature. According to the thermionic emission–diffusion theory and the solar cell theory, the changes in the photocurrent of the photodetector at zero bias with various system temperatures were calculated, which agreed well with the experimental data. This work demonstrates a promising approach to modulating the performance of a self-powered photodetector by heating and provides theoretical support for studying the thermal effect on the future photoelectric device. [ABSTRACT FROM AUTHOR]

Large-scale highly ordered ZnO nanorod arrays with precise period control and uniform distribution are easily fabricated via three-beam interference lithography, top anti-reflective coating and hydrothermal synthesis. This new method demonstrates an efficient way to fabricate large-scale highly ordered semiconductor nanorod arrays and could meet the needs of nanomaterial design, nanodevice optimization and nanosystem integration. [ABSTRACT FROM AUTHOR]

Application-oriented nanomaterial design and fabrication are highly necessary and are turning into a new trend nowadays. In this paper, large-scale patterned ZnO nanorod arrays (NRAs) with tunable arrangement, period and morphology are designed and fabricated via two-beam laser interference lithography and hydrothermal synthesis, through changing the buffer layer, photoresist (PR) template and growth conditions. The growth behavior, crystal structures and optical properties of patterned ZnO NRAs grown on a single-crystalline GaN film and a polycrystalline ZnO seed layer are studied. Furthermore, the relationship between the orientation of the PR template and the morphology of the corresponding ZnO NRAs is investigated. This study will benefit a deeper understanding of the rules of patterned growth of ZnO NRAs, further enhancing the controllability of arrangement, density and morphology of the patterned ZnO NRAs, and finally accelerating the process of integration and optimization of related functional nanodevices and nanosystems. [ABSTRACT FROM AUTHOR]