基于二氧化钛纳米管的染料敏化电池光阳极研究

本文报道了一种基于二氧化钛(TiO₂)纳米管的染料敏化太阳能电池。用二次阳极氧化法在钛箔上生长出高度有序的TiO₂纳米管薄膜, 然后将完整剥落的纳米管薄膜结合TiO₂纳米颗粒的浆料转移到掺杂氟的SnO₂透明导电玻璃(FTO)基底上, 从而获得一种特殊的染料敏化光阳极。对比了不同长度的TiO₂纳米管的电池性能, 发现经TiCl₄处理长度为32.8 μm的TiO₂纳米管对应的电池表现较好的光电转换效率, 达到4.15%。通过X射线衍射分析了高温退火对纳米管晶化结构的影响。电化学阻抗谱分析表明: 光电子传输对光阳极纳米管层厚依赖性强, 随着纳米管长度的增长, 界面电阻呈明显的减小, 这一结果对于理解和进一步改善染料敏化电池光阳极内部电子输运过程具有重要意义。     

基于金属网的叠层染料敏化太阳能电池

本文提出了一种新型染料敏化太阳能电池的叠层结构设计, 其中光阳极由导电玻璃上的第一层TiO₂纳米薄膜和不锈钢网上的第二层TiO₂纳米薄膜组成, 不同染料间的负反应相比混染共敏方式少. 此结构中引入的金属网, 减少了导电玻璃的使用片数, 从而减少入射光的损失; 同时也解决了两层不同TiO₂薄膜间的电连接性问题, 并提高电子传输和收集效率. 此叠层电池的光电转换效率达1.96%, 短路电流为8.4mA/cm², 相比相同电池厚度的单层电池, 效率提高约62%. 通过阻抗谱分析了叠层电池内部的电子传输, 给出叠层电池的等效电路图. 此外, 还发现电池厚度的增加及电子在不锈钢网表面的复合对光电性能有显著影响.     

高效CdS量子点敏化B/S共掺杂纳米TiO2太阳能电池的制备及光电性能研究

采用水热法制备硼硫(B/S)共掺杂纳米二氧化钛(B-S-TiO₂), 并配制成浆料, 利用丝网印刷技术在FTO导电玻璃上制备B-S-TiO₂薄膜; 用化学浴沉积(CBD)法制备了CdS量子点敏化B-S-TiO₂薄膜电极, 并用X射线衍射(XRD)、电子显微镜(TEM)、元素分析能谱(EDS)和紫外-可见光谱对其进行表征分析; 结果显示: B/S共掺杂不会改变TiO₂的晶型, 掺杂后的TiO₂吸收边带发生明显红移, 吸收强度显著增强; 同样用化学浴沉积的方法制备NiS工作电极, 用改性的聚硫化物((CH₃)₄N)₂S/((CH₃)₄N)₂S_n)电解液, 组装CdS量子点敏化硼硫(B/S)共掺杂纳米二氧化钛(B-S-TiO₂)太阳能电池, 并测试电池光电性能。测试结果表明, 在AM1.5G的照射下, 电池的能量转化效率(η)由3.21%增大到3.69%, 提高了14.9%, 电池获得高达 (V_oc)1.218 V的开路电压和3.42 mA/cm²的短路光电流(J_sc), 以及高达88.7%的填充因子(ff)。     

Ag2Se量子点共敏化固态染料敏化太阳能电池光电性能研究

采用水相共沉积法制备Ag₂Se量子点(QDs), 并与染料共敏化制备固态染料敏化太阳能电池(DSSCs)。考察了Ag₂Se量子点不同敏化方式(TiO₂/N719/QDs, TiO₂/QDs/N719)及敏化时间(0~5 h)对DSSCs性能的影响。通过透射电子显微镜(TEM)和紫外-可见光谱图(UV-Vis)对Ag₂Se量子点结构及光学性质进行了表征; 采用光调制光电流/电压谱(IMPS/VS)以及交流阻抗谱(EIS)对器件中载流子传输过程进行了研究。TiO₂/QDs/N719的电池器件比TiO₂/ N719/QDs具有更高的单色光量子转化效率(IPCE)及光电转化效率, 这是由于TiO₂/QDs/N719可以吸附更多的量子点和染料。随着Ag₂Se量子点敏化时间的延长, 光电转化效率先提高后降低, 最高达到3.97%。Ag₂Se量子点在器件中起到了阻挡层作用, 可以促进电子传输, 抑制电子-空穴复合。而随着量子点敏化时间超过2 h, 电子陷入陷阱的几率增加, 导致器件的光伏性能下降。     

柔性染料敏化太阳电池光阳极的优化及叠层电池的初步研究

在前期对冷等静压制备柔性染料敏化太阳电池(DSC)研究的基础上, 开展了浆料的优化及叠层DSC的研究。首先利用水热法处理由小颗粒P25调配的浆料, 发现处理后浆料的稳定性及DSC的效率得到了大幅提高。在P25浆料中加入不同比例200 nm TiO₂大颗粒提高光散射, 当P25与200 nm TiO₂比例为4:1时, DSC获得最高光电转换效率3.11%。在此基础上, 尝试用N719和N749双层染料敏化, 发现双层染料敏化后电池的效率介于N719和N749单独敏化的电池效率, 这可能是由于光阳极变厚不利于电子传输以及染料相互接触影响染料纯度, 光阳极厚度及电池结构有待于进一步优化。     

基于纳米多孔钛酸锂结构的染料敏化太阳电池复合光阳极研究

本研究探索了具有良好导电性能的多孔钛酸锂结构对传统氧化钛纳米晶光阳极的增强效果。以钛酸四丁酯、氢氧化锂为源, 采用溶胶-凝胶结合溶剂热反应和高温烧结方法, 制备了具有多孔结构的尖晶石型Li₄Ti₅O₁₂纳米粉体; 在表征其结晶性、微观形貌及孔结构的基础上, 将其与TiO₂纳米晶浆料复合, 制备复合光阳极, 并详细考察了钛酸锂掺量、结晶性和孔结构等对电池光电转换性能的影响规律。结果表明: 随热处理温度升高, Li₄Ti₅O₁₂结晶性增强, 晶粒尺寸明显增大, 比表面积下降。掺入Li₄Ti₅O₁₂粉体可以有效提高光阳极膜的染料负载量, 降低TiO₂/染料分子/电解液界面的电子传输阻抗, 从而明显提高复合光阳极的光电流密度(J_sc=13.91 mA/cm²)和开路电压(V_oc =0.8 V)。Li₄Ti₅O₁₂含量为1wt%的复合光阳极电池光电转化效率最好, 达到7.011%, 比纯TiO₂电池(效率: 5.384%)提高30%。     

CdS/TiO2纳米棒阵列复合材料的制备及其光电化学特性

以水热法在氟掺杂的氧化锡透明导电玻璃(FTO)上制备的TiO₂纳米棒阵列为衬底, 通过连续化学水浴沉积(S-CBD)法将CdS量子点 (QDs)沉积在TiO₂纳米棒上, 形成CdS/TiO₂阵列复合材料。分别利用高分辨透射电子显微镜(HRTEM)、 场发射扫描电子显微镜(FESEM)、 X射线衍射(XRD)和紫外可见光谱(UV-vis)等对样品的形貌、 晶型以及光吸收性能进行了表征。结果表明, TiO₂纳米棒阵列长度约为2.9 μm, CdS QDs的尺寸大约在5~9 nm。随着沉积层数的增加, CdS QDs的厚度增加, 同时伴随着光吸收边的红移。通过电流-电压特性曲线对其光电流-电压特性进行了分析, 发现光电流和光电转换效率均呈现出先增大后减小的规律。100 mW/cm²的光照下, 在S-CBD为7层时, 光电流和开路电压最大值分别达到2.49 mA·cm^-2和1.10 V, 而电池的效率达到最大值1.91%。     

TiO2形态对MAPbBr3太阳电池转化效率影响机制的研究

二氧化钛(TiO₂)是钙钛矿太阳电池中最常用的电子传输材料, 研究发现其形态对MAPbBr₃太阳电池的器件转化效率可产生直接影响。研究不同形态TiO₂对钙钛矿太阳电池转化效率的影响机制对进一步认识此类太阳电池的工作机理十分必要。本工作使用旋涂法制备了不同形态的TiO₂, 而后采用反溶剂室温结晶的方法在TiO₂基底上进一步制备MAPbBr₃(MA = CH₃NH₃)薄膜, 并通过X射线光电子能谱(XPS)详细研究了TiO₂与MAPbBr₃接触界面的能级位置关系。研究结果表明: 不同形态的TiO₂ 在与钙钛矿接触后形成的导带差异不同; 不同的导带能级差可直接影响MAPbBr₃钙钛矿电池中电子的传递与收集, 进而影响电池的转化效率。     

染料敏化太阳能电池阻挡层的制备及其性能研究

采用电子束蒸发法在光阳极导电玻璃基底上制备了一层致密的TiO2薄膜,并在氧氛围下进行不同温度的退火处理。以此TiO2薄膜为阻挡层来阻止电解质溶液中I3-与导电玻璃基底上光生电子的复合。分别利用X射线衍射（XRD）和X射线光电子能谱（XPS）对此薄膜的结构和成分进行表征。制备不同厚度的TiO2阻挡层薄膜并研究其对电池光电性能的影响。实验结果表明,阻挡层的引入有效地抑制了暗反应的发生,提高了染料敏化太阳能电池（DSSC）的开路电压、短路电流和光电转换效率,比未引入阻挡层的DSSC的光电转换效率提高了31.5%。     

一维二氧化钛光阳极的制备及在染料敏化太阳能电池中的应用综述

二氧化钛由于具有合适的禁带宽度、良好的光电性能、制作工艺简单等特点,目前广泛应用于染料敏化太阳能电池中。其中,大部分光阳极主要是由纳米颗粒组成,但纳米颗粒不利于电子和空穴的分离及传输、染料敏化太阳能电池的光电转化效率的提升。因此,可采用一维纳米结构光阳极替换纳米颗粒,这有利于提升染料敏化太阳能电池的光电转化效率。一维纳米材料具有较少的晶界,可为电荷提供通道、加速电子的传输,且能有效减少空穴/电子的复合,减少电子与染料的复合,从而提高效率。同时一维二氧化钛其较大的比表面积,不仅有利于染料吸附量增加,而且能有效提高电流密度。综述了几种一维二氧化钛制备方法的最新研究进展,分析了不同制备方法对二氧化钛光阳极的能带结构、光吸收特性、染料吸附量和电子传输过程的影响,介绍了近几年一维二氧化钛在染料敏化太阳能中的应用。最后,对一维二氧化钛在染料敏化太阳能电池中的应用进行了展望。     

Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS)

TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure.     

Fabrication of a multi-scale nanostructure of TiO(2) for application in dye-sensitized solar cells

We propose a highly ordered multi-scale nanostructure of TiO(2) for applications as an anode in dye-sensitized solar cells (DSSCs). The structure is composed of a TiO(2) blocking layer, a TiO(2) inverse opal main body, regularly arranged transport channels between contacting spherical voids of the TiO(2) inverse opal, and TiO(2) nanoparticles coated on the spherical surfaces of the voids. The ordered and continuous backbone of the inverse opal serves as the fast electron transport pathways while the regularly arranged transport channels enable easy transport of dye and electrolyte within the structure. A multi-cycle procedure was developed to enable fabrication of thick inverse opals and easy adjustment of the inverse opal thickness. An example structure was constructed, involving a blocking layer of 90?nm thickness, an inverse opal of 100?nm voids, transport channels of 30-50?nm openings, and nanoparticles 10-15?nm in size. An open-circuit voltage decay investigation showed a significant improvement in electron lifetime for the proposed multi-scale TiO(2) nanostructure based DSSC than that of a TiO(2) nanoparticle film based DSSC, revealing the superior electron recombination characteristic offered by the proposed TiO(2) nanostructure. The conversion efficiency of the DSSC assembled from such an anode structure can reach 4% with a short-circuit current density (J(sc)) of 8.7?mA?cm(-2) and open-circuit potential (V(oc)) of 0.76?V under AM 1.5 (100?mW?cm(-2)) illumination.     

Surface modified TiO2 nanostructure with 3D urchin-like morphology for dye-sensitized solar cell application

Three-dimensional (3D) urchin-like rutile TiO2 powders were synthesized by a mild hydrothermal method without any templates. An individual urchin-like TiO2 powder consists of self-assembled nanorods with a length of about 150 nm and width of about 10 nm. Additionally, the urchin-like TiO2 nanopowders were coated with an ultra-thin ZnO layer in order to modify the surface properties of the nanopowders, and the ZnO layer was confirmed by high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis. The ZnO-modified TiO2 was used as a photoelectrode of a dye-sensitized solar cell (DSSC) and the solar cell performances were investigated. In comparison with bare TiO2, ZnO-modified TiO2 improved the photovoltaic performances, i.e., energy conversion efficiency, open circuit voltage, and short circuit current were increased. The higher DSSC performance of ZnO-modified TiO2 was attributed to its higher dye loading and lower charge recombination rate.     

Correlating titania morphology and chemical composition with dye-sensitized solar cell performance

We have investigated the use of various morphologies, including nanoparticles, nanowires, and sea-urchins of TiO(2) as the semiconducting material used as components of dye-sensitized solar cells (DSSCs). Analysis of the solar cells under AM 1.5 solar irradiation reveals the superior performance of hydrothermally derived nanoparticles, by comparison with two readily available commercial nanoparticle materials, within the DSSC architecture. The sub-structural morphology of films of these nanostructured materials has been directly characterized using SEM and indirectly probed using dye desorption. Furthermore, the surfaces of these nanomaterials were studied using TEM in order to visualize their structure, prior to their application within DSSCs. Surface areas of the materials have been quantitatively analyzed by collecting BET adsorption and dye desorption data. Additional investigation using open circuit voltage decay measurements reveals the efficiency of electron conduction through each TiO(2) material. Moreover, the utilization of various chemically distinctive titanate materials within the DSSCs has also been investigated, demonstrating the deficiencies of using these particular chemical compositions within traditional DSSCs.     

Sputtered highly ordered TiO2 nanorod arrays and their applications as the electrode in dye-sensitized solar cells

For the first time, the TiO2 nanorod arrays have been prepared on ITO substrates at room temperature by dc reactive magnetron sputtering technique. These TiO2 nanorods have a preferred orientation along the (220) direction and are perpendicular to the ITO substrate. Both the X-ray diffraction and Raman scattering measurements show that the highly ordered TiO2 nanorod arrays have an anatase crystal structure. The diameter of the nanorod varies from 30 nm to 100 nm and the nanorod length can be varied from several hundred nanometers to several micrometers depending on the deposition time. The TiO2 nanorod arrays with about 3 micrometers length have been used as an electrode for dye-sensitized solar cell (DSSC). Short-circuit photocurrent density, open-circuit voltage, fill factor and light-to-electricity conversion efficiency at 100 mW/cm2 light intensity are estimated to be 12.76 mA/cm2, 0.65 V, 0.63 and 5.25%, respectively, for the DSSC made of the TiO2 nanorods.     

Solution Combustion Synthesis of TiO2 and Its Use for Fabrication of Photoelectrode for Dye-sensitized Solar Cell

Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis (SCS) method using three different fuels and for comparison, another type of TiO2 nano powder was synthesized by calcination of titanyl hydroxide. These TiO2 nano powders were used to fabricate photoelectrodes for the dye-sensitized solar cell (DSSC) and their performance was compared to that of the DSSC fabricated with Degussa P25 TiO2. The results showed that the SCS TiO2 could work well as photoelectrode for DSSC. The SCS TiO2 contained impurities of C and/or S, thus exhibiting visible light absorption and reduced band gap. The open circuit voltage and the fill factor both varied little among the various TiO2 and thus both had little effect on the photoelectrical conversion efficiency (η). However, the variation of η was seen to be in quite a good agreement with that of the short circuit current (Isc), suggesting that η was dominated by Isc. Isc was found to be enhanced by light scattering effect due to the presence of large particles but reduced by high impurity content due to an increase in electron transfer resistance. In addition, the specific surface area of the powders was found to be an important factor affecting the Isc and thus the η.     

Application of TiO2 nanoparticles coated multi-wall carbon nanotube to dye-sensitized solar cells

This study uses the sol-gel method to prepare TiO2 nanoparticle, and further applies TiO2 nanoparticle coating on the surface of the multi-wall carbon nanotube (MWCNT). As a result, TiO2-CNT composite nanoparticles are prepared to serve as photoelectrode material in dye-sensitized solar cell (DSSC). First, after acid treatment of MWCNT is used to remove impurities. Then, the sol-gel method is employed to prepare TiO2-CNT composite nanopowder. X-ray diffraction (XRD) pattern shows that after the TiO2 in TiO2-CNT composite nanopowder has been thermally treated at 450 degrees C, it can be completely changed to anatase phase. Furthermore, as shown from the SEM image, TiO2 has been successfully coated on CNT. The photoelectrode of DSSC is prepared using the electrophoretic deposition method (EPD) to mix the Degassa P25 TiO2 nanoparticles with TiO2-CNT powder for deposition on the indium tin oxide (ITO) conductive glass. After secondary EPD, a thin film of TiO2/CNTs with thickness 17 microm can be acquired. For the prepared TiO2-CNT composite nanoparticles, since MWCNT can increase the short-circuit current density of DSSC, the light-to-electricity conversion efficiency of DSSC can be effectively increased. Experimental results show that the photoelectric conversion efficiency of DSSC using CNT/TiO2 photoelectrode and N719 dye is increased by 41% from the original 3.45% to 4.87%.     

Ho~(3+)上转换发光在染料敏化太阳能电池中的应用

以水热和高温煅烧相结合的方法制备了掺Ho3+的TiO2上转换发光层,并将其组装在染料敏化太阳能电池中.通过XRD、荧光光谱仪、UV-vis和电池的光电性能测试,来分析上转换发光层的发光机理及其加入后对染料敏化太阳能电池性能的影响.结果表明,上转换发光层的引入有效地提高了DSSC的光电性能,在80mW/cm2红外光照射下最高光电转换效率达到了0.12‰,比未加上转换发光层的DSSC提高了360%.     

Effects of atomic layer deposited HfO2 compact layer on the performance of dye-sensitized solar cells

The performance of dye-sensitized solar cells (DSSCs) is limited by the back-reaction of photogenerated electrons from the photoelectrode back into liquid electrolyte. An atomic layer deposited (ALD) hafnium oxide (HfO₂) ultra thin compact layer was grown on the surface of the transparent conducting oxide (TCO) and its effects on the DSSC performance were studied with dark and illuminated current-voltage and electrochemical impedance spectroscopy measurements. It was found that this compact layer was effectively blocking the back-reaction of electrons from TCO to the liquid electrolyte, resulting in the overall photoconversion efficiency being enhanced by 66% compared to a DSSC with a conventional sol-gel processed TiO₂ compact layer. Reasons for the improved photovoltaic performance were attributed to passivation of the TCO surface, better electronic quality of the compact layer material and the higher compactness, shown by atomic force microscopic images, obtained from gas-based deposition methods. Also, an increased short-circuit current density suggests that the interfacial resistance for the injection of electrons from the porous nanoparticle network to TCO was reduced. Further, the theory of electron recombination at the TCO/compact layer/electrolyte interface was developed and used to explain the improved DSSC performance with an ALD HfO₂ compact layer.     

Fabrication and characterization of photoelectrode thin films with different morphologies of TiO2 nanoparticles for dye-sensitized solar cells

This study deals with the fabrication of three different morphologies of TiO2 nanoparticles to fabricate two-layer photoelectrode thin film for dye-sensitized solar cells (DSSC). The four different TiO2 morphologies are titania nanotubes (Tnt), TiO2 nanoparticles (H220), TiO2 nanoparticle (SP) and commercial DP-25 nanoparticles (P-25). To prepare the thin films of the photoelectrodes, the first layer is coated by H220 TiO2 nanoparticles, and the second is coated by 3 kinds of materials optimally proportionally mixed - P25, SP and Tnt. The photoelectric conversion efficiency of DSSCs with photoelectrodes fabricated using H220 reached 6.31%. Finally, the TiO2 nanaomaterials with four different morphologies were used to prepare a two layer photoelectrode with the structure of H220/P25-Tnt-SP which was combined with a Pt counter electrode to assemble DSSCs. These DSSCs had photoelectric conversion efficiencies of as high as 7.47%.