Characterization of a green and environmentally friendly sensitizer for a low cost dye-sensitized solar cell

Clean and cheap device, namely dye-sensitized solar cells (DSSCs) were fabricated using a natural dye extracted from Sambucus ebulus. We prepared five sample solutions with various pH in the extraction process to improve power conversion efficiency. The UV–visible absorption investigation of sample solutions and on photoanode show the dyes from J-type aggregation on a photoanode substrate. Redox properties of all sample solutions certify thermodynamically a charge transfer from excited state to conduction band TiO₂. The optical properties of various dye solutions were investigated and results showed darkness and bluish tint effect of dye solutions extracted in basic environment rather than those extracted in acidic condition. Moreover, in comparison to the basic condition, the dye solutions extracted in acidic environment were more saturated and colorimetrically less different from that one which extracted in neutral condition. Photophysical and photoelectrochemical performance of natural extraction dyes have been studied in dye-sensitized solar cell devices. The results show the rather high conversion efficiency of 0.57%, 1.15%, 1.02%, 0.35% and 0.15% of each individual dye extraction, respectively.     

The Development of Highly Fluorescent Hemicyanine and Dicyanoisophorone Dyes for Applications in Dye-Sensitized Solar Cells

Journal of Fluorescence - Ruthenium-based metal complex dyes have been employed extensively in dye-sensitized solar cells (DSSCs) as photosensitizers, but the cost and toxicity of metal complexes...     

Photovoltaic and impedance properties of dye-sensitized solar cell based on nature dye from beetroot

The present study involves fabrication and photovoltaic characterization including impedance properties of dye-sensitized solar cells based on natural dye from beetroot. The electrode of the cell was prepared with commercial Fluorine-doped Tin Oxide glass with 100 μm layer of nanostructured TiO₂ whereas, the counter electrode consisted of platinum-coated glass. Fresh juice was extracted from beetroot to use as dye. The dye exhibited high absorption in visible range. Photovoltaic measurements of the solar cell gave a short circuit current density (Jsc) of 130 μA/cm² and an open-circuit voltage (VOC) of 0.38 V under AM 1.5 illumination intensity. The VOC and Jsc showed linear behavior at higher values of illumination intensities. The conductance-voltage, the capacitance-voltage and the series resistance voltage characteristics of the dye solar cell was measured at frequency range from 5 kHz to 5 MHz to study performance of the dye-sensitized solar cells with natural dyes.     

Performance of dye-sensitized solar cells based on natural dyes

The natural dyes were successfully extracted from spinach, pitaya pericarp, orange peel, ginkgo leaf, purple cabbage and carrot, and then fabricated a dye-sensitized solar cells (DSSCs). It suggested that the absorption properties of natural dyes were strongly dependent on the types and concentration of pigments, and the purple cabbage exhibited an obvious absorption at 317 nm. Meanwhile, a higher conversion efficiency of 0.157% was obtained as the DSSCs were prepared by using purple cabbage, but the DSSCs showed a poor performance when the carrot was used as natural dyes, just achieved 0.01%. FTIR spectra revealed that purple cabbage showed a better adsorption properties between TiO₂ films and dyes than carrot. The dipping time was further investigated and proved that an optimal dipping time was 6 min, the DSSCs using purple cabbage could achieve 0.146% in photoelectric conversion efficiency.     

吲哚染料的电荷转移和能量转移：应用于无金属的染料敏感太阳能电池

对于应用于无金属染料敏感太阳能电池的吲哚染料用量子化学方法进行研究．对比研究吲哚染料的基态和激发态性质,揭示了随着绕丹宁环数目的增加,HOMO和LUMO的能量差减少,吸收光谱红移,但是束缚能增加,跃迁偶极矩减少;依据电荷差分密度,电荷和能量从苯乙烯转移到吲哚环和绕丹宁;电子空穴相干性主要表现在吲哚环和绕丹宁环,对于吲哚染料系统,存在一个绕丹宁环的体系的激子数目为30个原子,带有两个绕丹宁环的体系激子数目有40个原子．理论计算结果可以应用于无金属的染料敏感太阳能电池的吲哚染料的计算机辅助设计中．     

Investigation of effect of thiophene-2-acetic acid as an electron anchoring group for a photovoltaic device

Different anchoring groups such as thiophene-2-acetic and malonic acid were investigated for synthesis of new photosensitizers. The new dyes (photosensitizers) were made pure and determined by various analytical techniques. The chemical structure of synthesized materials was certified by analytical studies. UV-Visible and fluorescence spectra revealed intense fluorescence and absorption for organic photosensitizers. The cyclic voltammetry results showed that the two photosensitizers were suitable for dye sensitized solar cell preparation. The work electrode was gathered using tin (IV) oxide nanoparticles in dye-sensitized solar cells structure. The new photosensitizers and tin (IV) oxide were used for photovoltaic devices preparation. The power conversion efficiency was obtained as about 4.12 and 4.29% for Dye 1 and Dye 2, respectively.     

Effect of surfactant surface nature on the energy transfer efficiency (η) of a carbon dot-dye system

Carbon dots (CDs) have unique optoelectronic properties and are considered efficient fluorescent probes as organic dyes, semiconducting quantum dots, metallic clusters, etc. A carbon dot-dye system has been established to study alternative photoelectric conversion processes. For this purpose, a CuO-associated CD was synthesized using a green chemical method. The energy conversion efficiency was monitored using a cationic, anionic, and neutral dye. The nature of the dye has an important effect on the energy transfer process. This limitation from its electrostatic nature was overcome by introducing a surfactant into the system. Both positively and negatively charged surfactants were used in this study. The nature of the surfactant was found to have a significant effect on the energy transfer process within positively charged CDs and organic dyes. The individual interactions within surfactant-CD and surfactant-dye system can cause modification. This CD-dye-surfactant system with further modifications can be used appropriately in dye-sensitized solar cells.     

Laser-sintered mesoporous TiO2 electrodes for dye-sensitized solar cells

Low-temperature laser sintering has been successfully demonstrated to improve the overall conversion efficiency of dye-sensitized solar cells. Mesoporous TiO₂ electrodes were prepared from a colloidal solution of TiO₂ nanopowders by a laser direct-write technique and then sintered by a quasi-continuous-wave UV laser (λ=355 nm) for the fabrication of dye-sensitized solar cells. The overall conversion efficiency of the cells based on the laser-sintered TiO₂ electrodes was double that of the devices with non-laser-treated TiO₂ electrodes. This enhancement is attributed to both the removal of organic additives and the improved inter-nanoparticle electrical contacts induced by the laser-sintering process, which led to an increase in porosity and dye-absorption sites in the TiO₂ electrodes. PACS 61.80.Ba; 61.46.+w; 73.22.-f; 84.60.Jt     

Influence of Solvent on Dye-Sensitized Solar Cell Efficiency: What is so Special About Acetonitrile? (Part. Part. Syst. Charact. 5/2021)

The selection of solvent for preparing a working electrode (and to act as the electrolyte) is known to influence the efficiency of dye-sensitized solar cells. In this topical review, results taken from a systematic study are presented from the authors’ own lab examining how protic and aprotic solvents, as well as solvent polarity, affect adsorption of carboxylic dyes on the titanium dioxide nanoparticle surface and electron injection from the dye to the semiconductor. Adsorption of dye molecules on nanoparticle surfaces is measured through second harmonic light scattering and electron injection through ultrafast transient mid-infrared absorption. It is revealed that protic solvents do not allow direct adsorption of the dye onto the semiconductor surface, due to hydrogen bonding with the dye and competitive binding to the semiconductor surface. Aprotic solvents, on the other hand, support solvation of the dye molecules but also facilitate dye adsorption on the semiconductor nanoparticle. Among aprotic solvents, it is found that solvents with higher polarity result in larger adsorption free energy for the dye and faster electron injection. Overall, these studies reveal that aprotic solvents with high solvent polarity (such as acetonitrile) yield more efficient solar cell devices.     

Influence of anthocyanin co-pigment on electron transport and performance in black rice dye-sensitized solar cell

This work reports the novel contribution of chlorophyll b as natural anthocyanin co-pigment in unpurified black rice extract for improved electron transport and performance of natural dye-sensitized solar cell. The dyes are extracted as prominent photosensitizers by considering the concentration, the dye electronic structure, the extraction, and immersion time. The anthocyanin dye containing 1.92 mM cyanidin-3-O-glucoside structure has been extracted without purification. Interestingly, 0.33 mM chlorophyll b is found as a natural co-sensitizer in unpurified anthocyanin. The role of chlorophyll b supporting the electron transfer of anthocyanin dye will be investigated for improved cell performance. Both purified and unpurified dyes are compared in the same anthocyanin concentration. The combined Tauc plot and voltametric method will be conducted to show the interfacial electronic band edges of TiO₂-dye-electrolyte. Electrochemical impedance spectroscopy method will investigate electron transfer dynamic in both cell systems. As a result, chlorophyll b has dominantly acted as two intermediate states in boosting electron injection and dye regeneration to improve cell efficiency from 1.31 to 2.17 % due to the narrower LUMO–TiO₂ conduction band gap and the narrower HOMO-iodide (I ^?) potential gap, respectively. According to the electron transport, the co-sensitizer contributes to the smaller transport resistance (R _t?=?21.9 Ω), the higher chemical diffusion coefficient (D_n?=?1.696?×?10^?3 cm²/s), the higher chemical capacitance (C_μ?=?14.32 μF), and the faster electron transport (τ_d?=?39.88 μs).     

染料敏化纳米薄膜太阳电池实验研究

染料敏化纳米薄膜太阳电池（DSCs）的性能主要是由纳米多孔TiO２₂薄膜、染 料光敏化剂 、电解质、反电极（光阴极）等几个主要部分决定的.通过优化DSCs各项关键技术和材料的 性能，并通过小面积DSCs的系列实验和优化组合实验来检测各项参数对DSCs性能的影响，获 得在光照1个太阳（AM15）下，光电转换效率达到895%.这为进行产业化制备大面积DSCs 打下了良好基础. 关键词： 染料敏化 太阳电池 优化 效率     

Sensitized solar cells based on natural dyes

We have employed several natural dyes for application in dye sensitized solar cells (DSSC). Spinach, beet, red cabbage and strawberry are well known and have been already used. We then checked the opportunity to realize good DSSC with dyes available in Tunisia: Henna and Mallow (Mloukhya). Henna is a herb which has interesting reddish brownish dyeing properties used since antiquity for traditional decoration of skin, hair and fingernails in the Middle East and North Africa. The mallow is a green vegetable which is widely consumed in the same region. The optical absorption of the extracted dyes diluted in ethanol or distilled water were measured using UV–Vis spectrophotometer. The absorption in beet and red cabbage is more significant compared to the other dyes. Mallow and henna dyes present a noticeable band in the region 660 nm. Infra-red spectroscopy measurements were done to probe the structure and dynamics in our used dyes. In this paper, we present the steps followed in the making of our solar cells. The DSSC were assembled using two glass plates (supporting electrode and counter electrode) which are coated with transparent conducting oxide (TCO). The counter electrode is coated by a catalyst Pt (Platinum) to speed up the redox reaction with the electrolyte solution. The typical J–V curves of our solar cells under AM 1.5 using a density of power 100 mW/cm² were measured. Cells using henna and mallow as dyes present less degradation with time in the photoelectric characteristics. The mallow cell shows a good fill factor of 55% and a noticeable photoelectric conversion efficiency of 0.215%.     

丝网印刷制备染料敏化太阳能电池

染料敏化太阳能电池（DSSC）是太阳能电池研究的热点领域之一,使用丝网印刷技术制备以纳米晶多孔TiO₂薄膜为光阳极的DSSC具有低成本、简单的制备工艺和高的光电转换效率（PCE）的特点,这类太阳能电池受到人们广泛关注。为了提高这类太阳能电池的光电转换效率,通过采用不同网目相同印刷胶体制备了太阳能电池的光阳极优化印刷工艺十分重要,采用不同网目的方法研究印刷工艺对太阳能电池光伏性能的影响是十分有效的。用溶胶-凝胶法制备了TiO₂胶体,通过扫描电镜看出TiO₂薄膜具有多孔结构,其高比表面积有利于薄膜对染料分子的吸附,也有利于提高电池对太阳光的吸收率。经过高温烧结后丝网印刷的TiO₂薄膜展现了明显的锐钛矿结构较窄衍射峰,意味着TiO₂颗粒已经完全晶化且粒径增加。制备目数从100增到300导致网孔直径减少而薄膜变得更加致密,使得TiO₂薄膜的XRD衍射峰逐渐增强,而从300目增到400目时由于网孔过小导致TiO₂胶体通过网孔数量变小使得衍射峰强度下降。用不同网目印刷了单层TiO₂光阳极研究DSSCs光伏性能的变化情况,发现制备目数是200目和300目印刷太阳能电池的性能较好,而400网目印刷太阳能电池的性能最差,这与XRD观察的结果一致。再分别采用网目为100目、200目、300目和400目的印网将胶体印刷成了多层TiO₂薄膜,以此为基础组装DSSC。实验结果表明：通过不同组合网目的丝网印刷制备TiO₂薄膜,组装后的染料敏化太阳能电池的光电转换效率得到了显著提升,其中以300目+200目+100目三层叠印时得到的优化光阳极的最高电池效率达到6.9%。以丝网印刷的方法制备电极不需要进行任何化学处理,在较高网目制备底层的情况下印刷的薄膜均匀牢固,且电池制备的步骤简单、重复性好,能量转换效率较高。     

Material properties controlling photocurrent on TiO2 aggregates with plane orientation for dye-sensitized solar cells

Effective design of a dye-sensitized solar cell (DSSC) requires a clear understanding of the reaction mechanisms of the constituent cell materials. The relationship between structural and photo-electrochemical properties of the photo-anodic materials is of the first priority for such investigations. Highly oriented aggregates of anatase phase TiO₂ nanoparticles were deposited on Indium Tin oxide (ITO) glass substrates; over which N719 dyes were adsorbed through electrophoretic deposition under a strong magnetic field. The properties were evaluated by electrochemical measurements, UV–VIS spectroscopy, and electrical resistance measurements. The results showed that the absorbed photon number in the TiO₂ aggregates with adsorbed dye and their resistivity showed different dependences on the orientation of the crystal plane in the TiO₂ particle. The dependence of the photocurrent on the plane orientation of aggregates of dye-sensitized TiO₂ nanoparticles has been determined from a combination of the electrical conductivity of TiO₂ aggregate and the amount of dye adsorbed on the surface of TiO₂.     

Influence of saffron carotenoids and mulberry anthocyanins as natural sensitizers on performance of dye-sensitized solar cells

Ionics - This study reports the effect of saffron carotenoids and mulberry anthocyanins as natural sensitizers on electron transfer process and performance of dye-sensitized solar cells (DSSCs). A...     

One-pot,large-scale synthesis silica-encapsulated NIR alloy quantum dots CdSeTe within short time

Hydrothermal process has been employed to synthesize titanium oxide (TiO₂) bottle brush. The nanostructured bottle brushes with tetragonal nanorods of ~75 nm diameter have been synthesized by changing the nature of the precursors and hydrothermal processing parameters. The morphological features and structural properties of TiO₂ films were investigated by field emission scanning electron microscopy, X-ray diffraction, high-resolution transmission electron spectroscopy, Fourier transform Raman spectroscopy, and X-ray photoelectron spectroscopy. The influence of such nanostructures on the performance of dye-sensitized solar cells (DSSCs) is investigated in detail. The interface and transient properties of these nanorods and bottle brush-based photoanodes in DSSCs were analyzed by electrochemical impedance spectroscopic measurements in order to understand the critical factors contributing to such high power conversion efficiency. Surface area of sample was recorded using Brunauer–Emmett–Teller measurements. It is found that bottle brush provides effective large surface area 89.34 m² g^?1 which is much higher than TiO₂ nanorods 63.7 m² g^?1. Such effective surface area can facilitate the effective light harvesting, and hence improves the dye adsorption and the photovoltaic performance of DSSCs, typically in short-circuit photocurrent and power conversion efficiency. A best power conversion efficiency of 6.63 % has been achieved. We believe that the present device performance would have wide interests in dye-sensitized solar cell research.     

Spectral and orientational properties of new group of naphthalene derivatives of bicarboxylic acid in liquid crystal 7CB

The spectral and orientational properties of some dichroic fluorescent dyes (naphthalene derivatives of bicarboxylic acid) in some isotropic solvents and in an anisotropic matrix have been studied. The order parameter of the dyes in the nematogenic liquid crystal 7CB has been determined from measurements of polarized electronic absorption and fluorescence. The influence of the dye addition on the nematic-isotropic phase transition temperature of 7CB has been investigated. It was found that some of the dyes studied could be successfully utilized in guest-host liquid crystal display devices.     

三芳胺和二氢吲哚作为给体的染料对钴电解质的染料敏化太阳能电池性能的影响

合成了两种有机染料,三芳胺染料XS51和二氢吲哚染料XS52,并分别用于钴基电解质和碘基电解质的染料敏化太阳能电池中. 考察了染料结构对光物理性能、电化学性能和电池性能的影响. XS51为含有四个己氧基的三芳胺结构,表现出较好的空间位阻,从而提高了光电压. XS52中二氢吲哚的给电子能力强,从而短路电流较大. 同碘电解质相比,所合成的染料更适合用于钴电解质的染料敏化电池中. 在100 mW/cm²的光强下,基于染料XS52的钴电解质太阳能电池总的光电转换效率达到6.58%.     

Performance characteristics of dye-sensitized solar cells with counter electrode based on NiP-plated glass and titanium plate

The counter electrodes based on NiP-plated glass and titanium plate were prepared. The performance characteristics of the dye-sensitized solar cells with platinized NiP-plated glass electrode (Pt/NiP electrode) and platinized titanium plate electrode (Pt/TP electrode) were discussed. Pt/NiP electrode and Pt/TP electrode showed the same catalytic activity for triiodide reduction compared with platinized fluorine-doped tin oxide conducting glass electrode (Pt/FTO electrode). However, Pt/NiP electrode and Pt/TP electrode have the advantage over Pt/FTO electrode in reducing the sheet resistance and increasing light reflectivity, which resulted in improving the photovoltaic performance of dye-sensitized solar cells effectively. Compared with the cell using Pt/FTO electrode, the incident photon conversion efficiency of dye-sensitized solar cells with Pt/NiP electrode and Pt/TP electrode was increased by 20% and 5%, respectively, the overall energy efficiency of dye-sensitized solar cells with Pt/NiP electrode and Pt/TP electrode was increased by 32% and 27%, respectively.     

Synthesis of ZnO compound nanostructures via a chemical route for photovoltaic applications

A facile, low-temperature, and low-cost chemical route has been developed to prepare ZnO nanowire and nanosphere compound structures. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have systematically investigated the optical properties of the ZnO nanostructures by micro-Raman, photoluminescence, and transmission spectroscopy. The results demonstrate that the yielded ZnO nanostructures possess good optical quality with high light absorption. We have further successfully employed the obtained ZnO compound nanostructures in dye-sensitized solar cells. The light-to-electricity conversion results show that the compound nanostructure exhibits a significant enhancement of short-circuit current density due to the increased surface area and light scattering in the compound nanostructures. The present chemical route provides a simple way to synthesize various compound nanostructures with high surface area for nanodevice applications.