Toward high-efficiency perovskite solar cells with one-dimensional oriented nanostructured electron transport materials

The unique advantages of one-dimensional(1D)oriented nanostructures in light-trapping and chargetransport make them competitive candidates in photovoltaic(PV)devices.Since the emergence of perovskite solar cells(PSCs),1D nanostructured electron transport materials(ETMs)have drawn tremendous interest.However,the power conversion efficiencies(PCEs)of these devices have always significantly lagged behind their mesoscopic and planar counterparts.High-efficiency PSCs with 1D ETMs showing efficiency over 22%were just realized in the most recent studies.It yet lacks a comprehensive review covering the development of 1D ETMs and their application in PSCs.We hence timely summarize the advances in 1D ETMs-based solar cells,emphasizing on the fundamental and optimization issues of charge separation and collection ability,and their influence on PV performance.After sketching the classification and requirements for high-efficiency 1D nanostructured solar cells,we highlight the applicability of 1D TiO_(2)nanostructures in PSCs,including nanotubes,nanorods,nanocones,and nanopyramids,and carefully analyze how the electrostatic field affects cell performance.Other kinds of oriented nanostructures,e.g.,ZnO and SnO_(2)ETMs,are also described.Finally,we discuss the challenges and propose some potential strategies to further boost device performance.This review provides a broad range of valuable work in this fast-developing field,which we hope will stimulate research enthusiasm to push PSCs to an unprecedented level.

Controlling DNA Bundle Size and Spatial Arrangement in Selfassembled Arrays on Superhydrophobic Surface

The use of superhydrophobic surfaces(SHSs) is now emerging as an attractive platform for the realization of one-dimensional(1D) nanostructures with potential applications in many nanotechnological and biotechnological fields.To this purpose, a strict control of the nanostructures size and their spatial arrangement is highly required. However, these parameters may be strongly dependent on the complex evaporation dynamics of the sessile droplet on the SHS. In this work, we investigated the effect of the evaporation dynamics on the size and the spatial arrangement of self-assembled 1D DNA bundles. Our results reveal that different arrangements and bundle size distributions may occur depending on droplet evaporation stage. These results contribute to elucidate the formation mechanism of 1D nanostructures on SHSs.

Nanoscale ultraviolet photodetectors based on one- dimensional metal oxide nanostructures

Among the important optoelectronic devices, ultraviolet （UV） photodetectors show wide applications in fire monitoring, biological analysis, environmental sensors, space exploration, and UV irradiation detections. Research interest has focused on the utilization of one-dimensional （1D） metal oxide nanostructures to build advanced UV photodetectors through various processes. With large surface-to-volume ratio and well-controlled morphology and composition, 1D metal oxide nanostructures are regarded as promising candidates as components for building photodetectors with excellent sensitivity, superior quantum efficiency, and fast response speed. This article reviews the latest achievements with 1D metal oxide nanostructures reported over the past five years and their applications in UV light detection. It begins with an introduction of 1D metal oxide nanostructures, and the significance, key parameters and types of photo- detectors. Then we present several kinds of widely-studied 1D nanostructures and their photodetection performance, focusing on binary oxides with wide- bandgap （such as ZnO, SnO2, Ga203, Nb2Os, and WO3） and ternary oxides （such as Zn2SnO4, Zn2GeO4, and In2Ge2OT）. Finally, the review concludes with our perspectives and outlook on future research directions in this field.

Controlled Ag-driven superior rate-capability of Li4Ti5O12 anodes for lithium rechargeable batteries

The morphology and electronic structure of a Li4Ti5012 anode are known to determine its electrical and electrochemical properties in lithium rechargeable batteries. Ag-Li4Ti5012 nanofibers have been rationally designed and synthesized by an electrospinning technique to meet the requirements of one-dimensional （1D） morphology and superior electrical conductivity. Herein, we have found that the 1D Ag-Li4Ti5012 nanofibers show enhanced specific capacity, rate capability, and cycling stability compared to bare Li4Ti5012 nanofibers, due to the Ag nanoparticles （〈5 nm）, which are mainly distributed at interfaces between Li4Ti5O12 primary particles. This structural morphology gives rise to 20% higher rate capability than bare Li4Ti5O12 nanofibers by facilitating the charge transfer kinetics. Our findings provide an effective way to improve the electrochemical performance of Li4Ti5O12 anodes for lithium rechargeable batteries.

One-dimensional and two-dimensional synergized nanostructures for high-performing energy storage and conversion

To address the worldwide energy challenges,advanced energy storage and conversion systems with high comprehensive performances,as the promising technologies,are inevitably required on a timely basis.The performance of these energy systems is intimately dependent on the properties of their electrodes.In addition to the electrode materials selection and their compositional optimization,materials fabrication with the designed nanostructure also provides significant benefits for their performances.In the past decade,considerable efforts have been made to promote the search for multidimensional nanostructures containing both onedimensional(1D)and two-dimensional(2D)nanostructures in synergy,namely,1D-2D synergized nanostructures.By developing the freestanding electrodes with such unique nanoarchitectures,the structural features and electroactivities of each component can be manifested,where the synergistic properties among them can be simultaneously obtained for further enhanced properties,such as the increased number of active sites,fast electronic/ionic transport,and so forth.This review overviews the state-of-the-art on the 1D-2D synergized nanostructures,which can be broadly divided into three groups,namely,core/shell,cactus-like,and sandwich-like nanostructures.For each category,we introduce them from the aspects of structural features,fabrication methodologies to their successful applications in different types of energy storage/conversion devices,including rechargeable batteries,supercapacitors,water splitting,and so forth.Finally,the main challenges faced by and perspectives on the 1D-2D synergized nanostructures are discussed.

One Dimensional Nanostructures for Lithium-ion Batteries, Gas Sensors and Optoelectronics Applications

1 Results One dimensional (1D) nanostructures such as nanowires,nanotubes,nanorods and nanoribbons have been extensively investigated for a wide range of applications[1].Here,we present the synthesis,characterization and technological applications of several 1D nanostructures including SnO2 nanowires,CuO nanoribbons,CdSe nanowires and In2O3 nanowires.SnO2 nanowires were synthesized by thermal evaporation combined with a self-catalyzed growth procedure.Scanning electron microscopy (SEM) observation shows...

Lithographically directed assembly of one-dimensional DNA nanostructures via bivalent binding interactions

In order to exploit the outstanding physical properties of one-dimensional （1D） nanostructures such as carbon nanotubes and semiconducting nanowires and nanorods in future technological applications, it will be necessary to organize them on surfaces with precise control over both position and orientation. Here, we use a 1D rigid DNA motif as a model for studying directed assembly at the molecular scale to lithographically patterned nanodot anchors. By matching the inter-nanodot spacing to the length of the DNA nanostructure, we are able to achieve nearly 100% placement yield. By varying the length of single-stranded DNA linkers bound covalently to the nanodots, we are able to study the binding selectivity as a function of the strength of the binding interactions. We analyze the binding in terms of a thermodynamic model which provides insight into the bivalent nature of the binding, a scheme that has general applicability for the controlled assembly of a broad range of functional nanostructures.

Effects of indium doping concentration on the morphology and electrical properties of one-dimensional SnO_2 nanostructures prepared by a molten salt method

In this paper,indium doped SnO2 nanorods and nanowires have been prepared by the molten salt method,and the effects of indium doping concentration on the morphology and electrical properties of one-dimensional(1D) SnO2 nanostructures have been studied.It is found that indium doping concentration can affect the epitaxial growth,morphology and the electrical conductance of 1D SnO2 nanostructures.It is also found that the element made by using 6 mol% indium doped SnO2 nanorods responds to nitrogen gas.

Field electron emission from structure-controlled one-dimensional CuO arrays synthesized by wet chemical process

One-dimensional CuO nanostructure arrays have been synthesized on Cu foil by a low-temperature wet chemical process. Different CuO nanostrnctures including nanorods with facet heads, nanorods with needle-like tips and nanotubes are shaped simply by varying the concentration of oxidant. Field emission measurements show that CuO nanorods with needle-like tips are of superior performance than other shapes, having a turn-on field of 3.5 V/μm and a field enhancement factor of 2107. The good field emission performance is assigned to the sharp tips contributing to the high field enhancement effect and to the moderate density reducing the field screening effect.