天然染料敏化太阳能电池的制备——一个大学化学综合性实验

介绍一个研究探索型的大学化学综合性实验——天然染料敏化太阳能电池的制备。内容包括天然染料的提取,天然染料及其敏化的光阳极的紫外-可见吸收光谱的测试,染料敏化太阳能电池的制备以及光电性能测试等。通过本实验的实践,可以让学生更好地掌握相关专业知识,提高实验操作技能和专业素质,激发学生对科学研究的兴趣,培养科研探究能力。     

全固态介观太阳能电池:从染料敏化到钙钛矿

介观太阳能电池(Mesoscopic Solar Cells)作为新一代太阳能电池的突出代表, 具有原材料来源丰富, 制备工艺简单, 光电转换效率高等优点, 从而具有广阔的应用前景. 本工作简要评述了全固态介观太阳能电池从染料敏化太阳能电池(Dye-sensitized solar cells)发展到钙钛矿太阳能电池(Perovskite solar cells)过程中新材料、新技术和新概念的研究进展. 1998年, Grätzel课题组首次将固态有机空穴传输材料spiro-OMeTAD应用到染料敏化太阳能电池中, 制备出全固态染料敏化太阳能电池, 虽然仅获得了0.74%的光电转换效率, 但是却使得全固态染料敏化太阳能电池迅速发展成为介观太阳能电池的重要研究方向. 2012年, Park与Grätzel课题组合作, 使用钙钛矿型吸光材料(CH₃NH₃)PbI₃作为敏化剂, spiro-OMeTAD作为空穴收集层, 制备出光电转换效率达到9.7%的全固态介观太阳能电池, 又被称为钙钛矿太阳能电池. 自此, 基于钙钛矿材料的介观太阳能电池迅速成为太阳能电池领域的研究热点. 目前, 钙钛矿太阳能电池的最高公证效率已经达到20.1%. 钙钛矿太阳能电池作为介观太阳能电池商业化道路上里程碑式的突破, 在材料开发、界面优化以及器件稳定性方面的研究仍充满挑战, 也期待新的突破.     

方酸染料在染料敏化太阳能电池及氰离子检测中的应用研究

<正>染料敏化纳米晶二氧化钛太阳能电池制备简单、成本低、光电转换效率高,已成为当前光电转换器件研究的热点之一.但目前还有许多制约染料敏化太阳能电池光电转换效率的问题有待解决.基于目前染料敏化太阳能电池在长波区采光不足的问题,本论文深入研究了在红光区域具有强吸光能力的方酸类染料在染料敏化太阳能电池中的应用,重点考察了方酸染料的结构对其光电转换性质的影响,并开辟了一种协同敏化新技术,还利用方酸染料的β-环糊精包合物实现了水溶液中氰根离子的高选择性检测.具体研究结果如下:     

有机染料敏化纳米晶太阳能电池

本文综述了有机染料敏化纳米晶太阳能电池的研究现状,简要介绍了有机染料敏化纳米晶太阳能电池的结构和工作原理以及氧化物电极、对电极和电解质的设计思路和制备情况。重点介绍了有机染料的研究现状,包括香豆素类染料、多烯类染料、噻吩类染料、天然染料、半花菁类染料、卟啉类染料、三苯胺类染料、苝类染料等。同时讨论了若干影响有机染料敏化太阳能电池性能的因素,提出了提高光电转换效率的设想与对策,对未来的发展进行了展望。     

有机染料D-SS和D-ST用于染料敏化太阳能电池光敏剂的比较

为了揭示D-SS和D-ST分子敏化的染料敏化太阳能电池(DSSCs)的物理机制,采用密度泛函理论(DFT)、含时密度泛函理论(TDDFT)和自然键轨道(NBO)分析,模拟计算染料D-SS和D-ST分子的结构、紫外-可见吸收光谱和能级结构.D-SS的紫外-可见吸收光谱相比于D-ST的有明显的红移,而且D-SS分子的摩尔吸光系数也高于D-ST分子的.D-SS分子本应该比D-ST分子拥有更高的俘获太阳辐射光子的能力,但由于D-SS分子的最高占据分子轨道(HOMO)能级位置比氧化还原电解质(|-/|-3)的氧化还原能级高,处于光激发态的D-SS分子向TiO2电极注入电子而被氧化后,不能顺利地从电解质中得到电子而还原,使得D-SS分子俘获光子的能力不能充分发挥,从而严重地降低了由其敏化的DSSCs的光电性能和光电能量转换效率.揭示了D-SS敏化的DSSCs的光电性能,特别是光电能量转换效率比D-ST敏化的DSSCs的低的原因.染料敏化剂分子的HOMO能级的位置对于DSSCs来说也是很重要的,用于DSSCs的有机敏化剂分子的HOMO能级的位置必须低于氧化还原电解质的氧化还原能级.     

染料敏化太阳能电池固态电解质

染料敏化太阳能电池(DSCs)具有成本低廉、制作工艺简单、光电转换效率较高等优点,在新一代薄膜太阳能电池中,被认为是最具市场潜力的新型太阳能电池之一.电解质在染料敏化太阳能电池中起到桥梁作用,担负着还原染料、输运载流子完成电池内部循环的作用.液态电解质虽然效率高,但是易挥发和泄露,对电池的稳定性和寿命有很大的影响.因此...     

温度对多硫电解质及量子点敏化太阳能电池性能的影响

采用电化学的方法研究了温度对多硫电解质导电性能及量子点敏化太阳能电池光电性能的影响.结果表明:随着温度的升高,电解质的电导率逐步升高,多硫离子在电解质中的扩散阻力变小;另外,随着温度的升高,量子点敏化太阳能电池的光电转化效率逐渐降低,这主要是由于在较高的温度下,电池的暗反应逐渐增大和量子点的脱附引起的.     

双面进光太阳能电池透明对电极研究进展

近年来,太阳能电池（包括染料敏化、量子点敏化及钙钛矿太阳能电池）因其成本低、质量轻、效率高受到研究人员的广泛关注.双面进光太阳能电池是太阳光能通过光阳极以及透明对电极同时入射的器件,是近年来扩宽太阳能电池光利用率及能效以达到提高器件光电性能的主要手段,其中透明对电极的性能直接影响器件的背面进光效率,因此研究对电极对提高双面进光太阳能电池光电转化效率十分必要.本文针对传统对电极透光性低,成本高,光利用率低等问题,与双面进光的高光电转换效率以及低成本等特点对比,综合分析了透明对电极材料的选择及界面修饰改性等对双面进光染料敏化、量子点敏化及钙钛矿太阳能电池光电性能的影响及其应用前景.     

基于二级结构TiO_2纳米晶光阳极的高效染料敏化太阳能电池

本文报道了一种新型的二级结构TiO2纳米晶(nano-TiO2)光阳极的简单制备方法及其在高效染料敏化太阳能电池中的应用.通过添加适量TiCl4异丙醇溶液到传统nano-TiO2浆料中,可生成微米级nano-TiO2聚集体.该二级结构能有效提高光阳极光谱吸收和散射性能及电子传输和收集效率.基于这种结构光阳极的染料敏化太阳能电池光电性能有显著提高.在光阳极中将6μm厚传统nano-TiO2膜用相同厚度nano-TiO2聚集体替换,电池光电转换效率由5.03%提高到7.30%.进一步增加nano-TiO2聚集体的厚度能制备出更高光电转换效率的电池.     

聚合溶液pH值对染料敏化太阳电池中聚吡咯对电极结构和性能的影响

电化学合成聚吡咯(PPy)时,聚合电解液的pH值对PPy薄膜的形貌和性质有较大的影响,进而影响PPy薄膜对I-/I3-的电催化活性以及基于PPy对电极(CE)的染料敏化太阳电池(DSSCs)的光电转换性能.本文采用电化学恒电位方法,在掺杂氟的SnO2(FTO)导电玻璃上合成出了对甲苯磺酸根离子掺杂的聚吡咯(PPyTsO)电极,并将其作为DSSCs的对电极.通过改变吡咯聚合时聚合电解液的pH值,借助扫描电镜(SEM)、紫外-可见(UV-Vis)吸收光谱、X-射线光电子能谱(XPS)和循环伏安(CV)等表征技术,详细探讨了聚合溶液pH值对PPy CE形貌、结构及其对I-/I3-的电催化性能的影响.研究发现在pH 2.0下合成的聚吡咯对阴离子掺杂率最高且链共轭性最佳,具有对I-/I3-氧化还原介质最强的催化能力,基于此PPy CE的电池光电转化效率也最高.pH值太大或太小都不利于生成具有高掺杂率和高催化活性的PPy电极,组装成DSSCs后的光电转换效率也较低.     

牡丹花色苷的热稳定性和降解动力学

研究了pH值和温度对牡丹花色苷热稳定性的影响。动力学数据分析表明,牡丹花色苷的热降解符合一级反应动力学模型。在70～90℃条件下,当pH值为2.6、3.0、3.6、4.0和4.6时,牡丹花色苷的半衰期分别为27.0～7.9、32.1～8.5、27.9～8.9、35.9～9.4和27.3～10.7h。提高温度,花色苷降解反应速率增大;降解反应速率常数与温度的关系附合Arrhenius公式,反应活化能为48.4～69.4kJ/mol。牡丹花色苷单体的降解速率依次为矢车菊-3-O-二葡萄糖苷芍药-3-O-葡萄糖苷矢车菊-3,5-O-二葡萄糖苷芍药-3,5-O-二葡萄糖苷。牡丹花色苷降解生成褐色物质,褐变指数随加热时间的延长、加热温度的升高、pH值的增大而增大。     

Determination of total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method: collaborative study

This collaborative study was conducted to determine the total monomeric anthocyanin concentration by the pH differential method, which is a rapid and simple spectrophotometric method based on the anthocyanin structural transformation that occurs with a change in pH (colored at pH 1.0 and colorless at pH 4.5). Eleven collaborators representing commercial laboratories, academic institutions, and government laboratories participated. Seven Youden pair materials representing fruit juices, beverages, natural colorants, and wines were tested. The repeatability relative standard deviation (RSDr) varied from 1.06 to 4.16%. The reproducibility relative standard deviation (RSDR) ranged from 2.69 to 10.12%. The HorRat values were < or = 1.33 for all materials. The Study Director recommends that the method be adopted Official First Action.     

Characterization of anthocyanin extracts from maize kernels

The aim of the present work is to characterize the pigments present in the kernel of four native maize varieties related to the races Arrocillo, Cónico, Peruano, and Purepecha to determine their possible use as natural dyes. Total anthocyanin content is determined by a conventional spectrophotometric method, and anthocyanin analysis is done by high-performance liquid chromatography. The stability of the pigment at pH is also evaluated. The four maize samples contained anthocyanin in both the pericarp and aleurone layer. Total anthocyanin content among samples ranged from 54 mg/100 g of sample to 115 mg/100 g of sample. Anthocyanin profiles are almost the same among the four samples. Differences are observed only in the relative percentage of each anthocyanin. The anthocyanins identified are cyanidin-3-glucoside, pelargonidin- 3-glucoside, peonidin-3-glucoside, cyanidin-3-(6" malonylglucoside), and cyanidin-3-(3",6"-dimalonylglucoside). Anthocyanin extracts showed similar behavior in solutions with different pH. From pH 1-6 lambdamax values are maintained almost constant; however, above this pH value, a marked increase is observed in the bathochromic shifts, but the bluish color did not continue to change above pH 8.     

苯并三氮唑对硫增感溴化银乳剂的过增感效应

采用在曝光前后用苯并三氮唑溶液对未增感的和硫增感的立方体溴化银乳剂涂层的处理方法,考察了苯并三氮唑在溴化银成像过程的两个阶段:曝光潜影的形成阶段和潜影中心得以放大的显影阶段的作用.有意义地发现苯并三氮唑对硫增感溴化银乳剂有明显的过增感效应.实验结果表明:1)对于未增感的立方体溴化银乳剂涂层,在曝光前吸附了苯并三氮唑后会抑制潜影的形成,但曝光后吸附了苯并三氮唑对显影有十分明显的促进作用;2)对于硫增感的立方体溴化银乳剂涂层,曝光前用苯并三氮唑溶液处理后,产生显著的过增感效应,相对感光度可提高4倍左右,在曝光后用苯并三氮唑溶液处理,随着苯并三氮唑浓度的增加对显影也有一定程度的促进作用;3)对于硫增感的溴化银涂层,先经过388 mV的氧化还原缓冲液处理,再经苯并三氮唑溶液处理过的样片的感光度都要较未经缓冲液处理的提高4倍左右,这说明苯并三氮唑对硫增感乳剂产生的过增感效应只与硫敏化中心内(Ag₂S)_n的存在有关,与(Ag)_m是否存在无关.     

Photocatalytic oxidation of aqueous trichloroethylene using dye sensitized buoyant photocatalyst monitored via micro-headspace solid-phase microextration gas chromatography/electron capture detection and mass spectrometry

Trichloroethylene (TCE), a useful industrial agent which unfortunately exhibits carcinogenic properties, has become an extremely prevalent environmental contaminant. As such, new rapid, sensitive, and cost effective detection methods are needed for the identification of potential point sources of contamination. A new analytic micro-headspace method is described, utilizing solid phase micro-extraction (SPME) fibers and routine gas chromatography/electron capture detection (GC/ECD) for the detection of TCE to the 3.89 ppb level in aqueous samples. The polydimethylsiloxane (PDMS) fiber was shown to have the greatest analytical promise, with excellent sensitivity and minimal carry over. This method was employed in the monitoring of the photo-oxidation of TCE using buoyant TiO₂ coated microspheres, which were sensitized using natural anthocyanin dyes obtained from fruits. Solar mediated photo-oxidation was shown to be a successful method for the removal of aqueous organic contaminants. The dye sensitized system yielded excellent remediation with 93% of the TCE removed from the system within 12 h. As irradiation was executed, overall TCE concentrations were reduced, while the expected mineralization product of hydrochloric acid was produced. The micro-headspace SPME procedure described here, offers considerably improved sensitivity, with orders of magnitude improvement in method detection limits, over previously published micro-headspace methods.     

High-purity isolation of anthocyanins mixtures from fruits and vegetables--a novel solid-phase extraction method using mixed mode cation-exchange chromatography

Research on biological activity of anthocyanins requires the availability of high purity materials. However, current methods to isolate anthocyanins or anthocyanin mixtures are tedious and expensive or insufficient for complete isolation. We applied a novel cation-exchange/reversed-phase combination solid-phase extraction (SPE) technique, and optimized the use of water/organic buffer mobile phases to selectively separate anthocyanins. Crude extracts of various representative anthocyanin sources were purified with this technique and compared to 3 commonly used SPE techniques: C(18), HLB, and LH-20. Purified anthocyanin fractions were analyzed with high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) and mass spectrometry (MS) detectors and by Fourier transform infrared (FT-IR) spectroscopy. The UV-visible chromatograms quantitatively demonstrated that our novel technique achieved significantly higher (P<0.05) anthocyanin purity than the C(18) cartridge, the next best method, for 11 of the 12 anthocyanin sources tested. Among them, eight were purified to greater than 99% purity (based on UV-visible chromatograms). The new method efficiently removed non-anthocyanin phenolics. MS and FT-IR results semi-quantitatively confirmed extensive reduction of impurities. Due to strong ionic interaction, our sorbent capacity was superior to others, resulting in the highest throughput and least use of organic solvents. This new methodology for isolation of anthocyanin mixtures drastically increased purity and efficiency while maintaining excellent recovery rate and low cost. The availability of high purity anthocyanin mixtures will facilitate anthocyanin studies and promote the application of anthocyanins in the food and nutraceutical industries.     

HPLC-DAD–MS Analysis of Anthocyanins in Rose Wine Made From cv. Öküzgözü Grapes,and Effect of Maceration Time on Anthocyanin Content

The anthocyanin composition of rose wine made from cv. Öküzgözü, a variety of grape native to Turkey, and the effect of maceration time (3, 6, 12, 18, or 24 h) on the anthocyanin content of the wine have been investigated. High-performance liquid chromatography with diode-array detection (HPLC-DAD) and mass spectrometry (MS) were used for anthocyanin analysis. Thirteen different anthocyanins, including five glucosides, five acetyl glucosides, and three coumaroyl glucosides were identified and quantified. It was found that an important characteristic of Öküzgözü rose wine was the presence of a large amount of malvidin-3-glucoside and its acylated esters. The total anthocyanin content of the wine increased with increasing maceration time. On the basis of sensory analysis, the most preferred wine was that produced with 3-h maceration, because of its better color and general flavor attributes.     

Rapid quantitative analysis of individual anthocyanin content based on high‐performance liquid chromatography with diode array detection with the pH differential method

A new quantitative technique for the simultaneous quantification of the individual anthocyanins based on the pH differential method and high‐performance liquid chromatography with diode array detection is proposed in this paper. The six individual anthocyanins (cyanidin 3‐glucoside, cyanidin 3‐rutinoside, petunidin 3‐glucoside, petunidin 3‐rutinoside, and malvidin 3‐rutinoside) from mulberry (Morus rubra) and Liriope platyphylla were used for demonstration and validation. The elution of anthocyanins was performed using a C₁₈ column with stepwise gradient elution and individual anthocyanins were identified by high‐performance liquid chromatography with tandem mass spectrometry. Based on the pH differential method, the high‐performance liquid chromatography peak areas of maximum and reference absorption wavelengths of anthocyanin extracts were conducted to quantify individual anthocyanins. The calibration curves for these anthocyanins were linear within the range of 10–5500 mg/L. The correlation coefficients (r²) all exceeded 0.9972, and the limits of detection were in the range of 1–4 mg/L at a signal‐to‐noise ratio ≥5 for these anthocyanins. The proposed quantitative analysis was reproducible with good accuracy of all individual anthocyanins ranging from 96.3 to 104.2% and relative recoveries were in the range 98.4–103.2%. The proposed technique is performed without anthocyanin standards and is a simple, rapid, accurate, and economical method to determine individual anthocyanin contents.     

Anthocyanins HPLC-DAD and MS Characterization,Total Phenolics,and Antioxidant Activity of Some Berries Extracts

Extracts of indigenous wild blackberries, mulberries, bilberries, and blackthorns were analyzed for anthocyanin composition, anthocyanin content, total phenolics, and antioxidant capacity. Anthocyanins extraction with acidified methanol in ultrasonic condition (59 kHz, 60 min., 25°C) was carried out. The extracts were analyzed by high-performance liquid chromatography (HPLC) using a Dionex Ultimate 3000 apparatus equipped with photodiode array detector for qualitative characterization of the anthocyanins. The chromatograms revealed the presence of a large number of anthocyanins in fruits extracts: blackberries, 4 compounds; mulberries, 3 compounds; bilberries, 18 compounds; and blackthorns, 5 compounds. The most abundant anthocyanins were cyanidin-3-glucoside in blackberry, mulberry, and bilberry, and cyanidin-3-rutinoside in blackthorn extract. Structural information about anthocyanins was obtained by using a mass spectrometric method based on fully automated chip-nanoelectrospray ionization (nanoESI) high capacity ion trap (HCT). Anthocyanin content was quantified by the pH differential method and total phenolics were determined by Folin-Ciocalteu method. A Jasco V 530 UV-VIS spectrophotometer was used for absorbance measurements. The free radical scavenging activity of the berries extracts was performed by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The reduction of DPPH was followed by a spectrophotometric method. Also, a correlation of the antioxidant capacities of the extracts with their anthocyanin content and total phenolics was attempted.     

Application of sample disruption methods in the extraction of anthocyanins from solid or semi-solid vegetable samples

Cassis, a commercial powder obtained from blackcurrant juice (Ribes nigrum L.), was used to optimize the anthocyanin extraction by matrix solid-phase dispersion (MSPD) and by sea sand disruption method (SSDM). The optimum eluent conditions were 5.0 mL of MeOH/H2O (1:1, v/v) at pH 2. The extracts were analyzed by HPLC with diode-array detection (DAD) and the extraction efficiency was evaluated by statistical comparison (analysis of variance, ANOVA-single factor) of the compounds peak areas. The extraction efficiency for the MSPD procedure was dependent on the chemical nature of the C18 material but the optimized procedure yielded results similar to those obtained by the inexpensive sea sand disruption method (SSDM). This procedure also compared favorably to a previously published liquid-liquid extraction method. The optimized sea sand method was then used in the anthocyanin extraction from red grapes (Vitis vinifera L.) and strawberries (Fragaria ananassa D.) yielding chromatographic profiles similar to those reported in the literature for these products.