Assembly of one-dimensional polymer nanostructure arrays by photolithographic approaches

In this work, large area polymer nanostructure arrays with different patterns were successfully obtained by photolithographic approach and wetting anodic aluminum oxide (AAO) templates. First of all, the AAO templates with patterns were produced by photolithographic approach. Then the AAO/pattern membrane was used as a secondary template to fabricate polymer nanostructure arrays by solution-wetting and melt-wetting methods. The morphology of the polymer nanostructures has been characterized using scanning electron microscopy and transmission electron microscopy. The different factors have been discussed in the process of experiments.     

叠层有机太阳能电池中间电极的研究进展

有机太阳能电池具有成本低、质量轻、厚度薄、可溶液加工、制备工艺简单以及可制作大面积柔性器件等的优势,得到了研究者们的广泛关注。使用中间电极将不同带隙的子电池连接组成叠层有机太阳能电池,可以有效增加太阳能电池对入射光的吸收,以达到提高能量转换效率的目的。综述了叠层有机太阳能电池的重要组成部分中间电极材料的设计策略和近年来的研究进展,并展望了该类材料的发展趋势。     

叠层有机太阳能电池中间电极的研究进展

有机太阳能电池具有成本低、质量轻、厚度薄、可溶液加工、制备工艺简单以及可制作大面积柔性器件等的优势,得到了研究者们的广泛关注。使用中间电极将不同带隙的子电池连接组成叠层有机太阳能电池,可以有效增加太阳能电池对入射光的吸收,以达到提高能量转换效率的目的。综述了叠层有机太阳能电池的重要组成部分中间电极材料的设计策略和近年来的研究进展,并展望了该类材料的发展趋势。     

Building one-dimensional oxide nanostructure arrays on conductive metal substrates for lithium-ion battery anodes

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.     

CdS quantum dot-sensitized solar cells based on nano-branched TiO2 arrays

Nano-branched rutile TiO₂ nanorod arrays were grown on F:SnO₂ conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO₂ arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO₂ solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm² and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO₂ arrays, indicating an increase of 138% compared to those based on unbranched TiO₂ nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO₂ nanorod trunks.     

Organic solar cells based on conjugated polymers : History and recent advances

Organic solar cells have attracted huge attention because of their potential in the low-cost manufacturing of plastic solar modules featuring flexible, lightweight, ultrathin, rollable and bendable shapes. The power conversion efficiency of organic solar cells is now passing ~10%, which is a critical sign toward commercialization because organic solar cells surpass any other types of solar cells in terms of development speed. The encouraging efficiency enhancement could be realized by introducing a ‘bulk heterojunction’ concept that overcomes the weakness of organic semiconductors by minimizing their charge transport paths through making effective p-n junctions inside bulk organic films. However, there are several hurdles for commercialization, including stability and lifetime issues, owing to the bulk heterojunction concept. This review summarizes the important aspects of organic solar cells, particularly focusing on conjugated polymers as an active layer component.     

Efficient PbS/CdS co-sensitized solar cells based on TiO2 nanorod arrays

Narrow bandgap PbS nanoparticles, which may expand the light absorption range to the near-infrared region, were deposited on TiO₂ nanorod arrays by successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The thicknesses of PbS nanoparticles were optimized to enhance the photovoltaic performance of PbS QDSCs. A uniform CdS layer was directly coated on previously grown PbS-TiO₂ photoanode to protect the PbS from the chemical attack of polysulfide electrolytes. A remarkable short-circuit photocurrent density (approximately 10.4 mA/cm²) for PbS/CdS co-sensitized solar cell was recorded while the photocurrent density of only PbS-sensitized solar cells was lower than 3 mA/cm². The power conversion efficiency of the PbS/CdS co-sensitized solar cell reached 1.3%, which was beyond the arithmetic addition of the efficiencies of single constituents (PbS and CdS). These results indicate that the synergistic combination of PbS with CdS may provide a stable and effective sensitizer for practical solar cell applications.     

Recent advances in molecular electronics based on carbon nanotubes

Carbon nanotubes (CNTs) have exceptional physical properties that make them one of the most promising building blocks for future nanotechnologies. They may in particular play an important role in the development of innovative electronic devices in the fields of flexible electronics, ultra-high sensitivity sensors, high frequency electronics, opto-electronics, energy sources and nano-electromechanical systems (NEMS). Proofs of concept of several high performance devices already exist, usually at the single device level, but there remain many serious scientific issues to be solved before the viability of such routes can be evaluated. In particular, the main concern regards the controlled synthesis and positioning of nanotubes. In our opinion, truly innovative use of these nano-objects will come from: (i) the combination of some of their complementary physical properties, such as combining their electrical and mechanical properties, (ii) the combination of their properties with additional benefits coming from other molecules grafted on the nanotubes, and (iii) the use of chemically- or bio-directed self-assembly processes to allow the efficient combination of several devices into functional arrays or circuits. In this article, we outline the main issues concerning the development of carbon nanotubes based electronics applications and review our recent results in the field.     

染料敏化太阳能电池的进展及前景

国际太阳能光伏产业近年来发展迅猛,随着中国太阳能光伏发电技术的不断提高,为产业发展开拓了新思路,市场前景日趋广阔。笔者简明地介绍了染料敏化纳米薄膜太阳能电池的结构和原理;综合评述了染料敏化太阳能电池的研究进展,总结了染料敏化纳米薄膜太阳能电池的关键材料:(1)染料(2)电极材料(3)电解质等的研究现状和发展趋势,指出了各自存在的问题,提出了部分解决设想,并对其工业化前景进行了探讨。     

氢燃料电池电催化剂研究进展

目前铂（Pt）及其合金仍是氢燃料电池首选催化剂,但是Pt高价格、低储量及循环稳定性差等缺点严重阻碍了氢燃料电池商业化,因此发展低成本、高性能的新型非Pt催化剂和低Pt催化剂是实现氢燃料电池商业化的关键。本文围绕燃料电池催化开发及使用过程中存在的成本、稳定性和毒化问题,回顾了近年来阴离子交换膜燃料电池和质子交换膜燃料电池催化剂分别在提高阳极催化剂活性、降低阴极催化剂成本领域的最新研究进展,包括催化剂的组成、结构以及颗粒尺寸等对催化活性、稳定性的影响。最后针对燃料电池催化剂存在的问题,指出未来应基于原位观测和表征技术加强对碱性氢氧化机理的研究,同时开发高温制备小尺寸高有序度的有序铂合金阴极催化剂的方法是未来的研究重点。     

Effect of CdSe quantum dots on the performance of hybrid solar cells based on ZnO nanorod arrays

This paper reports the fabrication and interface modification of hybrid inverted solar cells based on ZnO nanorod arrays and poly (3-hexylthiophene). CdSe quantum dots (QDs) are grafted to the ZnO nanorod array successfully by bifunctional molecule mercaptopropionic acid to enhance the device performance. The power conversion efficiency of the device is increased by 109% from 0.11% to 0.23% under simulated 1 sun AM 1.5 solar illumination at 100 mW/cm² after the modification. The grafting of CdSe QDs effectively enhanced the excition generation and dissociation on the organic/inorganic interface. This work may provide a general method for increasing the efficiency of organic–inorganic hybrid solar cells by interface modification.     

Recent trends in polymer tandem solar cells research

Polymer solar cells have many intrinsic advantages, such as their light weight, flexibility, and low material and manufacturing costs. Recently, polymer tandem solar cells have attracted significant attention due to their potential to achieve higher performance than single cells. This trend article intends to provide the latest progress in polymer tandem solar cell technology with a focus on active layer materials and interfacial materials for sub-cell interconnection. Following an introduction of the structure and current status of polymer tandem solar cells, this article will review polymers which have been, and could be used, for tandem solar cells. Furthermore, this article will discuss the interconnecting layer consisting of p- and n-type interfacial layers, which is equally critical for polymer tandem solar cells. Finally, because tandem solar cell measurements are more complicated than that of single solar cells, this article will also address polymer tandem solar cell measurement issues.     

One dimensional nanostructure/nanoparticle composites as photoanodes for dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) show potential as a low cost alternative to silicon solar cells. Power conversion efficiencies exceeding 12% have been achieved for DSCs. Typical DSCs are based on TiO(2) nanoparticle photoanodes, which have numerous grain boundaries, surface defects and trap states as electrons transport from one particle to the other. Such defects and trap states increase back charge transfer (charge recombination) from the photoanode to electrolyte. One dimensional (1D) nanostructures such as nanofibers, nanorods, nanowires, and nanotubes can offer direct and fast electron transport to the electron collecting electrode. However, these 1D nanostructures have a major disadvantage of having insufficient surface area and inefficient dye attachment. To solve this challenge, mixtures of TiO(2) nanoparticles and 1D nanostructures (e.g. nanofibers, nanorods, nanowires, and nanotubes) are used to take advantage of the large surface area of nanoparticles and efficient charge transport of 1D nanostructures. In this article, we review the recent developments in using mixtures of 1D nanostructures and nanoparticles as photoanodes for efficient DSCs. Various randomly oriented and vertically aligned 1D nanostructures and their composites with nanoparticles are discussed. Future increase of efficiency in DSCs using 1D nanostructure/nanoparticle composites will rely on the optimization of diameters of 1D nanostructures, control of ratios of 1D nanostructures and nanoparticles, increase of crystallinity, and reduction of surface defects on the 1D nanostructures. This work will provide guidance for designing and growing appropriate 1D nanostructures, and combining them with nanoparticles at an optimal ratio for efficient DSCs.     

基于金属氧化物的乙醇检测气敏材料的研究进展

金属氧化物型半导体气体传感器是目前常用的乙醇检测手段,深入研究和改进金属氧化物型半导体材料是提升传感器性能的重要方式。本文首先论述了气敏检测的机理和影响因素,并综述了近年来发展的主要金属氧化物型半导体气敏材料,重点介绍了不同微观结构的Co₃O₄、ZnO、SnO₂及掺杂金属氧化物材料、氧化物异质结等的研究和发展情况,对它们的合成方法、结构特点以及结构与乙醇气敏性能之间的关系进行了探讨。分析表明,减小材料颗粒尺寸、构建大比表面积多孔结构、掺杂和复合改性,是提升金属氧化物材料气敏性能的有效措施。此外,基于传感器微小化的趋势,以微机电系统（MEMS）工艺为基础的微型传感器成为气体传感器的发展趋势。然而,目前针对金属氧化物气敏材料的制备依然缺乏一定的理论指导,气体检测缺乏相应的机理研究,亟需物理、化学、材料等多学科的相互结合,促进乙醇等半导体气体传感器的进一步发展。     

ZnO nanosheet arrays constructed on weaved titanium wire for CdS-sensitized solar cells

Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer adsorption and reaction method to make a photoanode. Nanoparticle-sensitized solar cells were assembled using these CdS/ZnO nanostructured photoanodes, and their photovoltaic performance was studied systematically. The best light-to-electricity conversion efficiency was obtained to be 2.17% under 100 mW/cm² illumination, and a remarkable short-circuit photocurrent density of approximately 20.1 mA/cm² was recorded, which could attribute to the relatively direct pathways for transportation of electrons provided by ZnO nanosheet arrays as well as the direct contact between ZnO and weaved titanium wires. These results indicate that CdS/ZnO nanostructures on weaved titanium wires would open a novel possibility for applications of low-cost solar cells.     

Recent advances on ion-imprinted polymers

Selective recognition of metal ions is a real challenge for a large range of applications in the analytical field (from extraction to detection and quantification). For that purpose, ion-imprinted polymers (IIPs) have been increasingly developed during the last 15 years on the principle of molecularly imprinted polymers (MIPs). Those imprinted materials are designed to mimic the binding sites of biological entities and assure an improved recognition of the template species. The aim of this review is to give the current state of the art in the conception of IIPs from the components to the polymerization process. Some applications of those materials will be also discussed.     

n-ZnO/p-Si 3D heterojunction solar cells in Si holey arrays

A wafer-scale, low-cost solar cell based on n-ZnO/p-Si 3D heterojunction arrays on holey Si substrates has been fabricated. This device shows a power-conversion efficiency of 1.2% and high photosensitivity. The present n-ZnO/p-Si heterojunction architectures are envisaged as potentially valuable candidates for next-generation photovoltaics.     

Hot embossing of moth eye-like nanostructure array on transparent glass with enhanced antireflection for solar cells

Antireflection (AR) silicon and glass surfaces are necessarily required for solar cells, because a reflective silicon solar cell with a glass covering will reflect a percentage of sunlight. In this work, we demonstrate a universal and scalable net-shape nanofabrication method for broadband nanostructured AR surface on transparent glass, intended for solar cell applications. Moth eye-like glass nanopillars with various diameters were successfully fabricated by a combination of precision hot embossing and ultrasonic vibration demolding process. The morphologies of nanopillars were detected to characterize different profiles formed by glass flow at elevated temperatures. Facile optical experiments were designed and conducted to measure the AR performance at varying wavelengths and angle of incidences and the proposed nanostructures exhibit excellent AR property. Additionally, a feasible optical modeling is developed and compared with the measurement to evaluate the theoretical optical behaviors of glass nanostructures based on their embossed shapes. The inexpensive and environmental hot embossing method with ultrasonic vibration demolding is expected to create AR glass nanostructured surfaces for widespread applications such as solar cells, displays and laser systems.     

Tuning of defects in ZnO nanorod arrays used in bulk heterojunction solar cells

With particular focus on bulk heterojunction solar cells incorporating ZnO nanorods, we study how different annealing environments (air or Zn environment) and temperatures impact on the photoluminescence response. Our work gives new insight into the complex defect landscape in ZnO, and it also shows how the different defect types can be manipulated. We have determined the emission wavelengths for the two main defects which make up the visible band, the oxygen vacancy emission wavelength at approximately 530 nm and the zinc vacancy emission wavelength at approximately 630 nm. The precise nature of the defect landscape in the bulk of the nanorods is found to be unimportant to photovoltaic cell performance although the surface structure is more critical. Annealing of the nanorods is optimum at 300°C as this is a sufficiently high temperature to decompose Zn(OH)₂ formed at the surface of the nanorods during electrodeposition and sufficiently low to prevent ITO degradation.