取向纳米ZnO/Cu_2O异质结阵列的制备及光电特性

以水热合成法制备的一维取向n型ZnO纳米线阵列为衬底,采用电化学沉积法在其上沉积生长一层p型Cu2O半导体包覆层,制备出了新型ZnO/Cu2O异质结纳米线阵列光敏器件.利用XRD、SEM、TEM、XPS、PL及光响应特性等测试方法对样品的形貌、晶体结构、化学成分及光电特性进行了分析表征.研究了生长条件对ZnO/Cu2O异质结纳米线阵列各种特性的影响.研究发现,适宜的沉积电压和沉积时间是保证ZnO/Cu2O异质结光敏器件具有适宜厚度核壳包覆层及较好光响应特性的关键因素.研究结果为ZnO及Cu2O半导体材料在光敏器件中的应用提供了实验基础.     

钙钛矿基近红外光电探测器

近年来,具有ABX₃晶体结构的金属卤化物钙钛矿材料因其可调带隙、高吸收系数、长载流子传输距离等光电学特性而在光电探测领域表现出良好应用前景,尤其是基于纯Sn或者Sn/Pb混合阳离子制备的杂化钙钛矿在760～1050nm范围的近红外光电响应性能非常优异,展现出高灵敏度、低暗电流和高探测率等多方面优势。为进一步拓宽钙钛矿的近红外以及红外响应波长范围,研究人员探索了将有机材料、晶体硅/锗、Ⅲ-Ⅴ族化合物、Ⅳ-Ⅵ族化合物、上转换荧光材料等作为互补光吸收层与钙钛矿结合制备异质结来构筑出宽谱响应的近红外光电探测器。基于以上研究,本文总结了当前拓宽钙钛矿光电探测器的光谱范围的有效途径。同时,对钙钛矿材料的近红外光电探测器的未来发展前景作出了展望。     

酞菁聚合物薄膜的电场取向和光导性能研究

通过电场取向法成功地制备了酞菁类聚合物(PPc)有序薄膜,并采用偏振荧光和TEM技术对其取向进行了研究.分别以该PPC有序薄膜和腙类作为载流子发生层和载流子传输层制备光电导体,发现其光导性能优于不加电场制备的PPc薄膜,呈现了光导性能提高的材料结构低维化效应.     

ZnO/Cu2O异质结中深能级表面光伏特性

采用恒电压沉积法在导电玻璃(FTO)上制备了具有三棱柱金字塔状的ZnO/Cu2O异质结薄膜. 利用场发射扫描电镜(FESEM)与X射线衍射仪(XRD)对薄膜的微观形貌和晶体结构进行了表征. 利用表面光电压谱(SPS)、场诱导表面光电压谱(FISPS)和相位谱(PS)研究了单一Cu2O与ZnO/Cu2O异质结薄膜的表面光伏性质. 结果表明, 与单一Cu2O薄膜相比, ZnO/Cu2O异质结薄膜的光伏响应范围拓展到了600~800 nm. 根据SPS, FISPS和PS的作用原理, 拓展部分的光伏响应归因于ZnO/Cu2O异质结中Cu2O层的深能级跃迁, 该跃迁在ZnO-Cu2O界面电场(方向由ZnO指向Cu2O)的作用下得到加强, 同时深能级跃迁产生的电子-空穴对在ZnO-Cu2O界面电场的作用下得到了有效分离和传输.     

电沉积法制备介孔TiO_2/CdS薄膜光电极

采用阴极恒电位沉积法,在介孔TiO2薄膜上制备了介孔TiO2/CdS薄膜光电极,用XRD,SEM,Raman,SPS和UV-Vis等多种手段对薄膜电极进行了表征.结果表明,CdS成功沉积到介孔TiO2的表面和孔道内,形成了异质结结构.通过光电流作用谱考察了该复合体薄膜电极的光电性能,结果表明,与单纯的介孔TiO2薄膜相比,其光电转换效率显著提高,这是由于CdS具有吸收可见光的特性以及CdS与介孔TiO2形成异质结从而使得光生载流子更容易分离的结果.     

Ag/ZnO/ZnSe三元异质结的合成及其可见光光催化性能

以Ag纳米线为模板,通过两步水浴法合成了Ag/ZnO/ZnSe三元异质结光催化材料。利用场发射扫描电子显微镜(FESEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)以及透射电子显微镜(FETEM)对样品的形貌和结构进行了表征。结果显示,Ag/ZnO/ZnSe三元异质结为蠕虫状的Ag/ZnO二元异质结外镶嵌着ZnSe小颗粒。在可见光下,对比纯Ag纳米线、纯ZnO纳米球、Ag/ZnO异质结对罗丹明B的可见光降解效率,结果发现Ag/ZnO/ZnSe异质结表现出了更高的光催化效率。其光催化性能的提高主要是由于Ag/ZnO/ZnSe异质结的作用促使电子空穴对的分离,降低了电子空穴对的复合机率,从而提高了材料的光催化效率。     

TiO2/CuS异质结的制备及光催化降解染料废水的研究

以原位沉淀法和水热法混合的合成手段,制备了TiO_2/CuS异质结光催化剂。这种异质结改善了单一TiO_2半导体光催化剂的缺陷,明显提高了太阳光下光催化降解甲基橙的效率。TiO_2与CuS之间形成的异质结结构和合适的能带结构能够扩展材料对太阳光谱的响应范围并且很好地收集和传输光诱导载流子,从而提高了载流子的分离效率,最终使半导体的光催化活性明显增强。结果表明,太阳光照射25min后,相比于TiO_2/MnS、TiO_2/CdS和TiO_2/ZnS异质结,TiO_2/CuS异质结(TiO_2和CuS的摩尔比为3∶1)对甲基橙的降解效果最佳,降解效率能达到97.3%。为提高半导体的光催化活性提供了一条可行的路径。     

还原石墨/氧化锌复合薄膜的制备及其光电转换性能

本工作研究不同过程还原的氧化石墨rGO/ZnO(reduced graphiteoxide/ZnO)复合膜的可见光激发光电转换性能。氧化石墨(GO)经KOH还原处理或NaBH4还原处理后,和氧化锌溶胶混合,通过旋涂法和热处理在F掺杂SnO2薄膜导电玻璃(FTO)衬底上形成复合薄膜。采用XRD、FTIR、FE-SEM、XPS、UV-Vis等方法对复合薄膜的晶相结构、微观形貌等进行表征,并测试了复合薄膜在可见光照射下的光电转换性能。GO的预处理过程对复合薄膜的结构影响显著,采用NaBH4对GO处理更有利于形成均匀薄膜。光电流测试结果表明不同复合薄膜均能实现可见光照射下产生光电流,其原理为rGO的光激发电子跃迁到ZnO,而空穴在rGO中迁移,在rGO与ZnO界面实现光生载流子分离。其中NaBH4处理后的rGO/ZnO复合薄膜光电流密度最大,达6×10-7A·cm-2。     

从晶体取向特点探讨ZnO薄膜的晶体不完整性

用MOCVD法在蓝宝石衬底上得到了ZnO(0002)膜, 并用XRD和SEM进行了表征. 结果表明， 薄膜中沿［0001］择优取向生长的柱状晶垂直于衬底表面, 晶柱之间存在着边界和间隙. X射线Ф扫描实验结果表明, 晶柱之间的取向偏差在3°~30°之间. X射线ω摇摆曲线和谱线宽度分析结果表明, 薄膜中的晶柱是由多个晶粒堆叠而成, 且晶粒之间的平均取向偏差也在2.6°以上. 实验结果表明, ZnO大失配度异质外延膜是c轴［0001］取向柱状多晶体, ZnO薄膜的结晶不完整性主要是由其柱状晶结构造成的.     

溶液法生长大面积超薄钙钛矿单晶薄膜

卤化物钙钛矿由于其独特的光电性质,在薄膜光电子器件领域具有极大潜力1。虽然许多工作都集中在多晶钙钛矿材料上,但单晶钙钛矿比多晶具有更低的缺陷态密度、更好的载流子输运能力和更高的稳定性2,3,可以有有效减少甚至消除载流子输运过程中的散射损失以及在晶界处的非辐射性复合4。采用单晶钙钛矿薄膜作为器件活性层被认为是进一步提高钙钛矿光电子器件性能的理想方案。目前,研究报道的钙钛矿单晶薄膜生长方法主要通过化学气相沉积和溶液空间限制法5,6,然而,所制备的薄膜厚度往往较厚,相应的器件性能也没有多晶薄膜的器件高7,因此,生长高质量的超薄大面积钙钛矿单晶薄膜至关重要。     

硫化锌与硫化锌/氧化锌异质结纳米线的化学气相沉积法制备与表征

介绍一种利用石墨还原快速制备大量硫化锌纳米线的方法,并分别合成了超晶格型、双轴型、核/壳型的硫化锌/氧化锌异质结纳米线。所合成的硫化锌纳米线存在六方纤锌矿和立方闪锌矿两种晶型,纳米线长度达几十微米,直径在20-50 nm,直径均匀且产量很高。在具有双轴型的硫化锌/氧化锌异质结中,首次发现具有超结构特征的氧化锌。HRTEM分析表明,硫化锌/氧化锌超晶格异质结界面为ZB-ZnS(111)∥ZnO(0001),而核/壳型异质结界面为W-ZnS(0001)∥ZnO(0001),这三个晶面分别为各自晶体的极性面,即所合成的硫化锌/氧化锌异质结中极性面相互平行。对ZnS 和ZnS/ZnO 异质结的生长机制进行了探讨,并对硫化锌纳米线与硫化锌/氧化锌异质结的光学性质进行了分析。     

ZnS nanoparticle decorated ZnO nanowall network: investigation through electron microscopy and secondary ion mass spectrometry

We report on the fabrication of ZnO nanowall networks decorated with ZnS nanostructures on aluminum substrates using simple chemical route. The structural features and elemental constituents of the ZnS/ZnO heterostructure systems have been extensively studied using electron microscopy and energy dispersive X‐ray spectroscopy. The light emission characteristics of the bare and heterostructured systems have been analyzed using room temperature photoluminescence spectroscopy. The decoration of ZnS nanostructures over ZnO nanowalls has been evidenced through secondary ion mass spectrometry (SIMS). The ‘matrix effect’ has been found to be prominent during SIMS analysis of the bare and heterostructured nanowalls indicating the presence of ZnS phase over ZnO surface. ‘MCs⁺‐SIMS’ has been employed to suppress the matrix effect and is found to be potentially effective in making a semi‐quantitative estimation of Zn and O surface–atom concentrations in both systems. The luminescence responses of the ZnS/ZnO heterostructures have been found to be strongly dependent on the extent of ZnS phase over ZnO. The higher luminescence responses in ZnS/ZnO heterostructures fabricated with smaller ZnS nanoparticles have been explained in terms of a mechanism of charge‐carrier transfer from ZnS to ZnO. Copyright © 2014 John Wiley & Sons, Ltd.     

Photoinduced charge transfer in ZnO/Cu(2)O heterostructure films studied by surface photovoltage technique

ZnO/Cu(2)O heterostructure films were prepared by a two-step electrodeposition method in aqueous solution on fluorine-doped tin oxide (FTO) substrates. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and UV-vis transmission measurements were utilized to characterize the films. Surface photovoltage (SPV) technique was used to investigate the process of photoinduced charge transfer. The results show that there is an electric field located at the interface between ZnO and Cu(2)O film and the photoinduced electrons in Cu(2)O film inject into ZnO under the effect of interfacial electric field with visible light irradiation. While under ultraviolet light illumination, the photoinduced electrons in Cu(2)O film accumulate at the surface of Cu(2)O film instead of injecting into ZnO under the action of surface built-in electric field of Cu(2)O film. The work function measurements confirm that the direction of interfacial electric field is from ZnO to Cu(2)O. These results are help to future design of high performance heterostructure photovoltaic devices.     

Self-organized hierarchical ZnS/SiO(2) nanowire heterostructures

Novel hierarchical heterostructures formed by wrapping ZnS nanowires with highly dense SiO(2) nanowires were successfully synthesized by a vapor-liquid-solid process. The as-synthesized products were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy equipped with an energy-dispersive X-ray spectrometer. Studies indicate that a typical hierarchical ZnS/SiO(2) heterostructure consists of a single-crystalline ZnS nanowire (core) with diameter gradually decreasing from several hundred nanometers to 20 nm and adjacent amorphous SiO(2) nanowires (branches) with diameters of about 20 nm. A possible growth mechanism was also proposed for the growth of the hierarchical heterostructures.     

花状ZnO/ZnS异质结构的简易合成、结构表征及光催化活性

采用简便的两步溶液相化学方法,在较低温度下(80℃),制备出了花状的ZnO/ZnS异质结构。分别利用X射线衍射、X射线光电子能谱仪、扫描电子显微镜、透射电子显微镜、紫外-可见光谱仪等测试手段对所制备的样品进行表征,结果表明ZnO/ZnS异质结构是由花状ZnO纳米结构和ZnS纳米粒子组成。在光降解罗丹明B(RhB)的测试中,ZnO/ZnS异质结构样品体现出了比ZnO前驱物和商业P25光催化剂更高的光催化效率,这主要可归因于异质结构更有利于电子-空穴的有效分离。ZnO/ZnS光催化剂体现出良好的循环稳定性。     

一种在固体基底上制备高度取向氧化锌纳米棒的新方法

采用廉价、低温的方法，在修饰过ZnO纳米粒子膜的ITO基底上成功制备出具有 高长径比、高度取向的ZnO纳米棒阵列，用扫描电子显微镜(SEM)，X射线衍射(XRD) ，高分辨透射电子显微镜(HRTEM)以及拉曼光谱对制备出的ZnO纳米棒的结构和形貌 进行了表征，测试结果表明，ZnO纳米棒是单晶，属于六方晶系，与基底直，上仍 沿(001)晶面择优生长的特征，并且ZnO纳米棒基本上无氧空位的存在，统计结果显 示，水热反应2h后90%以上的ZnO纳米棒直径为120～190nm，长度为4μm     

Hierarchical saw-like ZnO nanobelt/ZnS nanowire heterostructures induced by polar surfaces

Saw-like nanostructures composed of single-crystalline ZnO nanobelts and single-crystalline ZnS nanowires have been successfully synthesized by a vapor-solid process. Several techniques, including scanning electron microscope, transmission electron microscopy, and photoluminescence spectroscopy, were used to investigate the structures, morphology, and photoluminescence properties of the products. Due to the similar crystal habits of wurtzite ZnO and ZnS with chemically active Zn-terminated (0001) and chemically inactive O-terminated (or S-terminated) (000) polar surfaces, hierarchical saw-like nanostructures were considered to be formed by the initiation of a chemically active Zn-terminated ZnO (0001) polar surface. Photoluminescence properties of the heterostructures, different from pure ZnO nanobelts or ZnS nanowires, were also studied at room temperature.     

高度取向ZnO单晶亚微米棒阵列的制备与表征

通过低温压热的方法,在经过预先处理长满晶核的SnO2导电玻璃基底上制备出具有高度取向的ZnO亚微米棒阵列.用扫描电子显微镜(SEM)、选区电子衍射(SAED)及X射线粉末衍射(XRD),对制备出的ZnO亚微米棒的结构和形貌进行了表征.SEM测试结果表明,ZnO亚微米棒是六方型的,近乎垂直地长在基底上,棒的直径为400～500 nm,长度约为2 μm. SAED和XRD结果表明,ZnO亚微米棒为单晶,属于六方晶系,并且沿[001]方向择优取向生长.     

Synthesis and Photocatalytic Properties of Coupled Nanocrystalline ZnO/ZnS in Nation Membrane

T The coupled nanocrystalline ZnO/ZnS was fabricated and immobilized in Nafion membrane by using sodium sulfide (Na_2S) as the single anion precursor. The molar ratio of ZnO to ZnS can be controlled by simply adjusting the reaction time. The as-prepared ZnO/ZnS-Nafion samples were characterized by various methods, including optical absorption, X-ray diffraction and high-resolution transmission electron microscopy. These coupled ZnO/ZnS nanocrystals embedded in Nafion membrane displayed excellent photocatalytic activities for their efficient charge separation properties. A mechanism of ZnO/ZnS nanoparticle fabrication in Nation was deduced from the solubility difference, and the photocatalytic mechanism of coupled ZnO/ZnS was discussed as well.     

A study on electrodeposited of ZnO/ZnS heterostructures

ZnO/ZnS heterostructures were synthesized by a two steps electrochemical deposition method. Firstly, ZnS layer was deposited from an aqueous solution containing Na₂S₂O₃ and ZnSO₄ onto indium-doped tin oxide (ITO) coating glass substrate at two deposition potentials. Then, ZnO nanostructures were deposited from an aqueous solution of Zn(NO₃) onto ZnS surface. The as-obtained samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman and UV-visible analysis. The results indicate that the electrodeposition of ZnS layer at ?0.9 V give the best proprieties of ZnO/ZnS heterostructures. Homogeneous and uniform surface of ZnO/ZnS heterostructure was confirmed by AFM images. The XRD patterns indicates a high crystallinity of ZnO/ZnS. A high transmittance of 65% was also noted from UV-Visible spectra and band gap energy as large as 3.6?eV was found.