ZnO纳米棒光阳极的制备及其天然染料敏化研究

采用溶胶-凝胶法和旋转涂覆法在FTO导电玻璃上制备ZnO种子层,以Zn(NO3)2和六亚甲基四胺(HMT)的混合溶液为生长液在ZnO种子层上制备出ZnO纳米棒薄膜,利用X射线衍射(XRD)、扫描电镜(SEM)对ZnO种子层及纳米棒薄膜的晶相及表面微观形貌进行了表征;研究了生长液浓度、生长时间对ZnO纳米棒薄膜生长的影响。实验表明,制备排列整齐的ZnO纳米棒阵列薄膜最佳条件为90℃环境下,基底竖直放置在0.025mol/L的生长液中,生长4h,纳米棒平均直径80nm左右。从新鲜草莓、桑葚中提取天然色素,对ZnO纳米棒电极进行敏化,组装成光电池;测试敏化电极的吸收光谱及光电池的伏安特性曲线。结果表明,桑葚色素在可见光区有更强的吸收特性,由桑葚色素敏化的电极组装的光电池,在模拟太阳光下,得到开路电压为228.75mV,短路电流为189μA,填充因子为0.37,光电转换效率为5.5×10-4。     

介孔ZnO微球的制备及其在染料敏化太阳能电池中的应用

制备了一种新型的染料敏化太阳电池的光阳极,该电极由溶剂合成的具有高比表面积和良好光散射特性的ZnO介孔微球组成。采用X射线衍射、扫描电子显微镜、能谱仪及N2吸附脱附等手段,分析了介孔ZnO微球的结构和形貌。所得介孔微球尺寸在亚微米范围,比表面积约为50m2.g-1。将ZnO介孔微球成功应用到染料敏化太阳电池中,当光阳极为3μm时,组成的原型器件的短路电流密度约为4.5mA.cm-2,开路电压约为602mV,转换效率可达1.28%。研究结果表明,ZnO介孔微球是一种优异的染料敏化太阳电池的光阳极材料。     

基于ZnO纳米片/纳米球复合结构光阳极的染料敏化太阳电池

将电沉积和溶剂热方法制备的ZnO纳米片阵列和ZnO纳米球组装成ZnO纳米片/纳米球复合结构光阳极,并应用 透射电镜(TEM)、扫描电镜(SEM)、X射线衍射仪(XRD)对合成产物的形貌和晶相进行表征.染料敏化太阳电池性能测试表 明,与单一光阳极结构的ZnO纳米片基电池相比,基于更大比表面积和更强光散射效应的ZnO纳米片...     

微等离子法制备原位生长TiO2薄膜电极研究

采用微等离子体氧化法制备用于染料敏化太阳能电池的原位生长TiO2薄膜电极。筛选适合制备较高光电性能原位生长TiO2薄膜电极的电解液,利用扫描电镜(SEM)、X射线衍射(XRD)和交流阻抗谱(EIS)考察电解液类型对所得TiO2薄膜电极的表面形貌、晶相组成和内部阻抗的影响,并利用X射线光电子能谱(XPS)和红外吸收(IR)研究染料敏化剂与TiO2薄膜表面的相互作用。结果表明,以(NH4)2SO4为电解液制备TiO2薄膜的光电性能高于硫酸体系所得TiO2薄膜的光电性能,短路电流、开路电压和光电转换效率分别为49μA/cm2,652mV和0.095%。薄膜主要由大量的金红石和少量的锐钛矿和钛组成,并且以(NH4)2SO4为电解液制备的薄膜中,TiO2含量较高。膜层较厚,约为7.5μm。薄膜的内部阻抗相对较小,有利于染料敏化太阳能电池光电性能的提高。所得TiO2薄膜电极的光电性能较高;cis-Ru(dcbpy)2(NCS)2染料可以吸附在微等离子氧化法制备的TiO2薄膜表面。染料cis-Ru(dcbpy)2(NCS)2敏化后的TiO2薄膜XPS谱中出现了O=C-O基团中的C1s吸收峰,说明染料可以吸附在微等离子氧化法制备的TiO2薄膜表面。在红外光谱中,在1 737nm处出现了一个吸收峰,应为酯键羰基振动所引起的,由此可以推断染料与TiO2表面应以类酯键形式结合。     

染料敏化太阳能电池TiO2薄膜电极的染料吸附性能研究

采用手工刮涂法制备了染料敏化太阳能电池( DSSC)的TiO2薄膜电极,用解吸的方法和正交试验研究了DSSC电池TiO2薄膜电极的染料吸附性能,并结合统计分析方法对染料吸附试验数据进行了分析处理.研究结果表明TiO2薄膜电极具有最优染料吸附性能的烧结条件为:以2℃/min的速率升温至450℃,保温50 min后随炉冷却...     

三维ZnO/CdS光电极的制备及其光电化学性能研究

采用两步水热法,在FTO基底上制备了ZnO/CdS阵列薄膜。利用扫描电镜(SEM)和透射电镜(TEM)对样品的形貌和结构进行了表征,发现通过改变水热前驱体溶液中的表面活性剂,可以有效改变ZnO/CdS光电极的形貌。制备了一维和三维结构的ZnO/CdS薄膜,以制备的薄膜作为光电极,研究了其光电化学性能,发现三维ZnO/CdS电极具有更高的光电流密度和能量转化效率,分析了电极光电化学性能提升的内在机制。     

29种天然染料敏化的太阳电池的性能研究

采用超声波萃取法从29种天然植物中提取染料, 测试天然染料的紫外-可见光(UV-vis)吸收光谱,探讨天然染料所 含的色素种类。采用水热法制备了TiO₂薄膜电极,用所提取的29种天然染料敏化TiO₂光 电极并将其组装成染料敏化太阳电池(DSSCs)。测试天然染料敏化的DSSCs 的光电性能结果显示,天然染料敏化的DSSCs的开路 电压Voc为0.46~0.64 V,短路电流I_sc为0.07~3.61mA· cm－2,其中山竹皮敏 化的DSSCs光电性能最佳,对应的I_sc和光电转换 效率η分 别为3.61mA·cm－2和2.13%。从天然 染料中挑选出7种不同吸收波段色素的染料进行协同敏化,UV-vis吸收光谱测试结 果显示混合染料的吸收峰一般有微小偏移。光电性能测试结果表明,协同敏化后的DSSCs的 性能一般都介于天然染料单独敏 化的两个DSSCs的性能之间,其中山竹皮和芥蓝协同敏化的DSSCs的η最高,为1.70%。对实验结果进行深入分析,探讨提高天然染料 敏化的DSSCs光电性能的途径。     

氧流量对TiO_2薄膜光电性质的影响

采用直流反应磁控溅射法在FTO基底上制备了TiO2薄膜,研究了在不同氧流量条件下TiO2薄膜的拉曼光谱、表面形貌和透射光谱,并将TiO2薄膜用N719染料进行敏化,制备了染料敏化太阳电池,测试了电池的I-V特性曲线。实验结果表明:随着氧流量的增加,电池的短路电流和光电转换效率先增加而后降低,在15cm3时达到最大;薄膜为锐钛矿和金红石的混合晶体结构;氧流量对薄膜的表面形貌影响不大,薄膜都表现出疏松多孔的表面结构。     

NiSe纳米材料合成及其在染料敏化太阳能电池中的应用

探寻电催化性能优异、廉价的对电极材料是染料敏化太阳能电池发展过程中所面临的重大挑战之一。本文将采用一步溶剂热法合成NiSe纳米材料,采用喷涂法制备Ni Se薄膜,并作为染料敏化太阳能电池对电极。利用循环伏安曲线、塔菲尔极化曲线、电化学阻抗谱表征对电极的电催化性能。实验结果表明,在I–/I3~–体系中,Ni Se对电极展现出了与铂电极相当的电催化性能。通过染料敏化太阳能电池组装与测试,表明基于NiSe对电极的染料敏化太阳能电池拥有良好的光伏性能,其能量转换效率达到5.27%,与基于铂电极的电池效率(5.34%)相当。     

天然染料作为Zn2TiO4太阳能电池敏化剂的研究

从植物的叶、花、果实和果皮中提取出7种天然染料,通过对它们的UV-vis吸收光谱比较发现,从月季叶中提取的染料表现出较好的光响应性.采用溶胶-凝胶法制备了纳米晶Zn2TiO4薄膜电极,并利用X射线衍射(XRD)、扫描电镜(SEM)对其晶相及表面形貌进行了表征;制备了月季叶染料敏化Zn2TiO4电极,并以此为光阳极组装了...     

Polydisperse Aggregates of ZnO Nanocrystallites: A Method for Energy‐Conversion‐Efficiency Enhancement in Dye‐Sensitized Solar Cells

ZnO films consisting of either polydisperse or monodisperse aggregates of nanocrystallites were fabricated and studied as dye‐sensitized solar‐cell electrodes. The results revealed that the overall energy‐conversion efficiency of the cells could be significantly affected by either the average size or the size distribution of the ZnO aggregates. The highest overall energy‐conversion efficiency of ～4.4% was achieved with the film formed by polydisperse ZnO aggregates with a broad size distribution from 120 to 360 nm in diameter. Light scattering by the submicrometer‐sized ZnO aggregates was employed to explain the improved solar‐cell performance through extending the distance travelled by light so as to increase the light‐harvesting efficiency of photoelectrode film. The broad distribution of aggregate size provides the ZnO films with both better packing and an enhanced ability to scatter the incident light, and thus promotes the solar‐cell performance.     

Synthesis of ZnO nanostructure films by thermal evaporation approach and their application in dye-sensitized solar cells

Zinc oxide (ZnO) films were prepared successfully by simple thermal evaporation of zinc acetate dihydrate at low temperature onto FTO (fluorine-doped tin oxide) glass substrates coated with thin ZnO seed layer. The synthetic parameter such as temperature was found to determine the morphology of nanostructures. ZnO nanorod (NR) and nanoparticle (NP) films have been synthesized at 245 and 350 °C, respectively, for 6 h. The dye-sensitized solar cells (DSSCs) were fabricated using the ZnO nanostructure films as photosensitized electrodes. A maximum photoelectric conversion efficiency (PCE) of 1.56%, and short-circuit photocurrent density of 5.12 mA/cm² were achieved with the ZnO NP-based DSSC. The PCE increase was ascribed to the reduced recombination loss and prolonged electron lifetime according to electrochemical impedance spectroscopy (EIS).     

Development of Nano‐TiO2 dye sensitised solar cells on high mobility transparent conducting oxide thin films

The optical transmission of dye‐sensitised solar cells (DSCs) can be tuned by altering the dye and/or particle size of the mesoporous TiO₂ layers, to allow their application as the top device in tandem solar cells. To benefit from this semi‐transparency, parasitic optical losses by the transparent electrodes must be minimised. This work investigates the influence of using two different transparent conductors, namely, the high mobility material titanium doped indium oxide (ITiO) and fluorine doped tin oxide (FTO) as electrodes for semi‐transparent DSCs. The overall NIR transparency through the DSCs increased significantly as each FTO electrode was replaced by an ITiO electrode. This increase was from 20–45% in the 1300–700 nm wavelength range for fully FTO‐based cells, to about 60% for fully ITiO‐based cells, across the same spectrum. DSCs prepared on these electrodes exhibited short circuit currents ranging from 14·0–14·9 mA/cm². The conversion efficiency of the cell with ITiO as both the front and rear electrodes was 5·8%, which though significant, was lower than the 8·2% attained by the cell using FTO electrodes, as a result of a lower fill factor. Improvements in the ITiO thermal stability and in the processing of the TiO₂ interfacial layer are expected to improve the cell efficiency of such single DSC devices. The high current density and optical transparency of ITiO‐based DSCs make them an interesting option for tandem solar cells. Copyright © 2008 John Wiley & Sons, Ltd.     

Sensitization of zinc oxide photoanode with an indoline dye

A dye‐sensitized solar cell (DSC) made of nanoporous ZnO film on aluminum‐doped zinc oxide (ZnO/AZO) transparent substrate has higher solar‐to‐electric energy conversion efficiency than a DSC consisting of nanoporous ZnO film deposited on conventional fluorine‐doped tin oxide (ZnO/FTO) transparent substrate. The ZnO/AZO DSC gave an overall conversion efficiency of 7.2% whereas the ZnO/FTO yielded a conversion efficiency of 4.5%. The film‐substrate orientation and higher light harvesting of the nanoporous ZnO film on the AZO after heating in air are mainly attributed to the higher energy conversion efficiency of the ZnO/AZO DSC. Copyright © 2012 John Wiley & Sons, Ltd.     

Spray deposited ZnO and Ga doped ZnO based DSSC with bromophenol blue dye as sensitizer: Efficiency analysis through DFT approach

Dye sensitized solar cells based on spray deposited ZnO and Ga doped ZnO (GZO) thin film were fabricated with Bromophenol Blue as the photo sensitizer. XRD results show the hexagonal wurtzite phase of ZnO and GZO thin films with c-axis growth orientation, and the diminished crystalline nature of GZO thin film as the effect of doping. FE-SEM results revealed the morphology induced internal light interaction capability of GZO thin film for better harvesting of photon energy. Photovoltaic studies showed that the DSSC fabricated with GZO thin film has obtained enhanced power conversion efficiency (1%) than the ZnO thin film based DSSC (0.2%), as a result of Ga doping. To investigate the obtained photovoltaic performance of the device, the electronic properties of Bromophenol Blue dye were theoretically analyzed with Density Functional Theory (DFT) study.     

Transparent,Double‐Sided,ITO‐Free,Flexible Dye‐Sensitized Solar Cells Based on Metal Wire/ZnO Nanowire Arrays

Transparent, double‐sided, flexible, ITO‐free dye‐sensitized solar cells (DSSCs) are fabricated in a simple, facile, and controllable way. Highly ordered, high‐crystal‐quality, high‐density ZnO nanowire arrays are radially grown on stainless steel, Au, Ag, and Cu microwires, which serve as working electrodes. Pt wires serve as the counter electrodes. Two metal wires are encased in electrolyte between two poly(ethylene terephthalate) (PET) films (or polydimethylsiloxane (PDMS) films) to render the device both flexible and highly transparent. The effect of the dye thickness on the photovoltaic performance of the DSSCs as a function of dye‐loading time is investigated systematically. Shorter dye‐loading times lead to thinner dye layers and better device performance. A dye‐loading time of 20 min results in the best device performance. An oxidation treatment of the metal wires is developed effectively to avoid the galvanic‐battery effect found in the experiment, which is crucial for real applications of double‐metal‐wire DSSC configurations. The device shows very good transparency and can increase sunlight use efficiency through two‐sided illumination. The double‐wire DSSCs remain stable for a long period of time and can be bent at large angles, up to 107°, reversibly, without any loss of performance. The double‐wire‐PET, planar solar‐cell configuration can be used as window stickers and can be readily realized for large‐area‐weave roll‐to‐roll processing.     

Realizing the Potential of ZnO with Alternative Non‐Metallic Co‐Dopants as Electrode Materials for Small Molecule Optoelectronic Devices

High performance indium tin oxide (ITO)‐free small molecule organic solar cells and organic light‐emitting diodes (OLEDs) are demonstrated using optimized ZnO electrodes with alternative non‐metallic co‐dopants. The co‐doping of hydrogen and fluorine reduces the metal content of ZnO thin films, resulting in a low absorption coefficient, a high transmittance, and a low refractive index as well as the high conductivity, which are needed for the application in organic solar cells and OLEDs. While the established metal‐doped ZnO films have good electrical and optical properties, their application in organic devices is not as efficient as other alternative electrode approaches. The optimized ZnO electrodes presented here are employed in organic solar cells as well as OLEDs and allow not only the replacement of ITO, but also significantly improve the efficiency compared to lab‐standard ITO. The enhanced performance is attributed to outstanding optical properties and spontaneously nanostructured surfaces of the ZnO films with non‐metallic co‐dopants and their straightforward integration with molecular doping technology, which avoids several common drawbacks of ZnO electrodes. The observations show that optimized ZnO films with non‐metallic co‐dopants are a promising and competitive electrode for low‐cost and high performance organic solar cells and OLEDs.     

SnO2 nanosheet as a photoanode interfacial layer for dyesensitized solar cells

SnO2 nanosheet films about 200 nm in thickness are successfully fabricated on fluorine-doped tin oxide (FTO) glass by a facile solution-grown approach. The prepared SnO2 nanosheet film is applied as an interfacial layer between the nanocrystalline TiO2 film and the FTO substrate in dye-sensitized solar cells (DSCs). Experimental results show that the introduction of a SnO2 nanosheet film not only suppresses the electron back-transport reaction at the electrolyte/FTO interface but also provides an efficient electron transition channel along the SnO2 nanosheets, and as a result, increasing the open circuit voltage and short current density, and finally improving the conversion efficiency for the DSCs from 3.89% to 4.62%.     

Universal Electron Injection Dynamics at Nanointerfaces in Dye‐Sensitized Solar Cells

Initial nanointerfacial electron transfer dynamics are studied in dye‐sensitized solar cells (DSSCs) in which the free energy and kinetics vary over a broad range. Surprisingly, it is found that the decay profiles, reflecting the electron transfer behavior, show a universal shape despite the different kinds of dye and semiconductor nanocrystalline films, even across different device types. This renews intuitive knowledge about the electron injection process in DSSCs. In order to quantitatively comprehend the universal behavior, a static inhomogeneous electronic coupling model with a Gaussian distribution of local injection energetics is proposed in which only the electron injection rate is a variant. It is confirmed that this model can be extended to CdSe quantum dot‐sensitized films. These unambiguous results indicate exactly the same physical distribution in electron injection process of different sensitization films, providing limited simple and important parameters describing the electron injection process including electronic coupling constant and reorganization energy. The results provide insight into photoconversion physics and the design of optimal metal‐free organic dye‐sensitized photovoltaic devices by molecular engineering.