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Towards Rational Designing of Efficient Sensitizers Based on Thiophene and Infrared Dyes for Dye-Sensitized Solar Cells  [PDF]
Ahmad Irfan,Abdullah G. Al-Sehemi,Shabbir Muhammad
Journal of Quantum Chemistry , 2014, DOI: 10.1155/2014/796790
Abstract: Geometries, electronic properties, and absorption spectra of the dyes which are a combination of thiophene based dye (THPD) and IR dyes (covering IR region; TIRBD1-TIRBD3) were performed using density functional theory (DFT) and time dependent density functional theory (TD-DFT), respectively. Different electron donating groups, electron withdrawing groups, and IR dyes have been substituted on THPD to enhance the efficiency. The bond lengths of new designed dyes are almost the same. The lowest unoccupied molecular orbital energies of designed dyes are above the conduction band of TiO2 and the highest occupied molecular orbital energies are below the redox couple revealing that TIRBD1-TIRBD3 would be better sensitizers for dye-sensitized solar cells. The broad spectra and low energy gap also showed that designed materials would be efficient sensitizers. 1. Introduction There exist many potential renewable energy technologies in the form of solid-state devices, such as, solar cells, which convert solar energy in the form of light to the more practical form of electricity. In 1991, Regan and Gratzel invented dye-sensitized solar cells (DSSCs). Solar cells are among the most important devices that can be used to solve the world’s energy and environmental needs. The DSSCs are still in the early stages. The DSSC is a promising solar cell technology [1–4]. The metal-free organic dyes as sensitizers such as boron-dipyrromethene (BODIPY) dyes [5], indoline dyes (D102 and D149) [6], infrared absorbing thiapenta-carbocyanine dye [7] and so forth, have been intensively studied. Improvement of absorption of the solar spectrum has been investigated mainly by adding different types of dopants such as transition metal elements, nonmetal elements, nitrogen, sulfur, boron, carbon nanotubes, and so forth [8–16]. The geometric characteristics of organic thiophene based dye (THPD) are of great attention for many applications, including photodynamic therapy light harvesting, nonlinear absorption, and optical storage. The UV/visible absorption areas of organic thiophene based dye are of great value when preparing them as sensitizers for solar cells. Theoretical investigations of the physical properties of the dye sensitizers are very important in order to disclose the relationship among the performance, structure, and properties. It is also supportive to design and produce novel dye sensitizer with high performance. Recently, we have designed the THPD and then explained it as a good sensitizer (17a). Generally THPD absorbs in the visible region. We are expecting that the
Utilization of Naturally Occurring Dyes as Sensitizers in Dye Sensitized Solar Cells  [PDF]
Nipun Sawhney,Soumitra Satapathi
Physics , 2015,
Abstract: Dye sensitized Solar cells (DSSCs) were fabricated with four naturally occurring anthocyanin dyes extracted from naturally found fruits/ juices (viz. Indian Jamun, Plum, Black Currant and Berries) as sensitizers. Extraction of anthocyanin was done using acidified ethanol. The highest power conversion efficiencies ({\eta}) of 0.55% and 0.53% were achieved for the DSSCs fabricated using anthocyanin extracts of blackcurrant and mixed berry juice. Widespread availability of these fruits/juices, high concentration of anthocyanins in them and ease of extraction of anthocyanin dyes from these commonly available fruits render them novel and inexpensive candidates for solar cell fabrication.
Theoretical Investigation of Novel Tetrathiafulvalene- Triphenylamine Sensitizers

- , 2016, DOI: 10.3866/PKU.WHXB201605031
Abstract: 在简单结构的D-π-A三苯胺光敏染料(YD1)中引入不同数量的四硫富瓦烯(TTF)单元作为次级电子给体以增强有机光敏染料的给电子能力,设计了两个结构分别为D-D-π-A (YD2)以及2D-D-π-A (YD3)的光敏染料分子,并且采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)分别模拟计算了纯光敏剂分子及其吸附二氧化钛团簇后的几何构型、电子结构以及光物理性能。采用周期性密度泛函理论模拟计算光敏染料分子在二氧化钛(101)面吸附的表面形貌以及态密度(DOS)。计算结果表明,TTF单元的引入不仅可以有效减少光敏染料分子的团聚,还可以提升其吸收性能。此外,光吸收效率(LHE)、电子注入驱动力(ΔGinject)以及DOS的计算结果显示,YD2和YD3理论上可以呈现出比YD1更高的短路电流密度(Jsc)以及开路电压(Voc)。因此,通过本文的理论研究表明,TTF单元可以作为有机光敏染料中的次级电子给体来改善光敏染料的性能。
Two novel sensitizers with D-D-π-A (YD2) and 2D-D-π-A (YD3) structures were designed by introducing different numbers of tetrathiafulvalene (TTF) unit as the auxiliary electron donor based on the simple D-π-A triphenylamine sensitizer (YD1) to enhance the electron donating ability. The geometries, electronic structures, and optical properties of YD1-3 before and after binding to TiO2 clusters were investigated. Owing to introduction of TTF unit, YD2 and YD3 show larger steric hindrance and a narrower band gap than YD1. Moreover, the estimated light-harvesting efficiency (LHE), injection driving force (ΔGinject) values, and density of states (DOS) calculations indicate that YD2 and YD3 should show higher short-circuit photocurrent density (Jsc) and open-circuit photovoltage (Voc) than YD1 with the presence of TTF unit. All of the results indicate that TTF unit can be used as an auxiliary electron donor in organic sensitizers to improve their photovoltaic properties
Natural Carotenoids as Nanomaterial Precursors for Molecular Photovoltaics: A Computational DFT Study  [PDF]
Teresita Ruiz-Anchondo,Norma Flores-Holguín,Daniel Glossman-Mitnik
Molecules , 2010, DOI: 10.3390/molecules15074490
Abstract: In this work several natural carotenoids were studied as potential nanomaterial precursors for molecular photovoltaics. M05-2X/6-31+G(d,p) level of theory calculations were used to obtain their molecular structures, as well as to predict the infrared (IR) and ultraviolet (UV-Vis) spectra, the dipole moment and polarizability, the pKa, and the chemical reactivity parameters (electronegativity, hardness, electrophilicity and Fukui functions) that arise from Conceptual DFT. The calculated values were compared with the available experimental data for these molecules and discussed in terms of their usefulness in describing photovoltaic properties.
First-principles study of Carbz-PAHTDDT dye sensitizer and two Carbz-derived dyes for dye sensitized solar cells  [PDF]
Narges Mohammadi,Feng Wang
Physics , 2014,
Abstract: Two new carbazole-based organic dye sensitizers are designed and investigated in silico. These dyes are designed through chemical modifications of the conjugated bridge of a reference organic sensitizer known as Carbz-PAHTDDT (S9) dye. The aim of designing these dyes was to reduce the energy gap between their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and to red-shift their absorption response compared to those of the reference S9 dye sensitizer. This reference dye has a reported promising efficiency when coupled with ferrocene-based electrolyte composition. To investigate geometric and electronic structure, density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were conducted on the new dyes as well as the reference dye. The present study indicated that the long-range correction to the theoretical model in the TD-DFT simulation is important to produce accurate absorption wavelengths.The theoretical studies have shown a reduced HOMO-LUMO gap and red-shifted absorption spectra for both of the new candidate dyes. Such findings suggest that the new dyes are promising and suitable for optoelectronic applications.
Density Functional Theory (DFT) Study of Coumarin-based Dyes Adsorbed on TiO2 Nanoclusters—Applications to Dye-Sensitized Solar Cells  [PDF]
Corneliu I. Oprea,Petre Panait,Fanica Cimpoesu,Marilena Ferbinteanu,Mihai A. G?r?u
Materials , 2013, DOI: 10.3390/ma6062372
Abstract: Coumarin-based dyes have been successfully used in dye-sensitized solar cells, leading to photovoltaic conversion efficiencies of up to about 8%. Given the need to better understand the behavior of the dye adsorbed on the TiO 2 nanoparticle, we report results of density functional theory (DFT) and time-dependent DFT (TD-DFT) studies of several coumarin-based dyes, as well as complex systems consisting of the dye bound to a TiO 2 cluster. We provide the electronic structure and simulated UV-Vis spectra of the dyes alone and adsorbed to the cluster and discuss the matching with the solar spectrum. We display the energy level diagrams and the electron density of the key molecular orbitals and analyze the electron transfer from the dye to the oxide. Finally, we compare our theoretical results with the experimental data available and discuss the key issues that influence the device performance.
Characterization of solution processed TiOx buffer layers in inverted organic photovoltaics by XPS and DFT studies  [PDF]
Ivan S. Zhidkov,Ernst Z. Kurmaev,Michel A. Korotin,Andrey I. Kukharenko,Achilleas Savva,Stelios A. Choulis,Danila M. Korotin,Seif O. Cholakh
Physics , 2014,
Abstract: We present the results of XPS measurements (core levels and valence bands) of solution processed TiOx thin films prepared from titanium butoxide (C16H36O4Ti) diluted in isopropanol which is a common sol-gel route for fabricating TiOx electron selective contacts for ITO/TiOx inverted organic photovoltaics bottom electrodes. XPS Ti 2p and valence band spectra show the presence of additional features which are absent in spectra of titanium butoxide deposited on Si and are attributed to appearance of Ti^{3+} valence states in ITO/TiOx. This conclusion is confirmed by density functional theory electronic structure calculations of stoichiometric TiO2 and oxygen deficient TiO_{2-1/8}. XPS C 1s measurements show the formation of C-O and O-C=O bonds which evidence the presence of residual carbon which can draw oxygen from the film network and induce the formation of fraction of Ti3+ states in TiOx films.
DFT Studies on the electronic structures of indoline dyes for dye-sensitized solar cells  [PDF]
Journal of the Serbian Chemical Society , 2010,
Abstract: A series of indoline dyes with promising efficiency for dye-sensitized solar cells (DSSCs) were studied using the density functional theory at the B3LYP/6-31g (d) level. The ground-state geometries, electronic structures and absorption spectra of these dyes are reported. The calculated results indicate that the energy levels of the HOMOs and LUMOs of these dyes are advantageous for electron injection. Their intense and broad absorption bands as well as favorable excited-state energy levels are key factor for their outstanding efficiencies in DSSCs.
Molecular Design of Indolizine Derivative as Sensitizers for Organic Dye-Sensitized Solar Cells

- , 2015, DOI: 10.3866/PKU.WHXB201505211
Abstract: 采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)方法研究了9个新的中氮茚[3, 4, 5-ab]异吲哚(INI)为给体的染料敏化剂性质.对影响电池效率的光捕获效率、电子注入、染料再生和电荷复合等重要因素与D5和D9染料进行了对比.计算表明,设计的INI系列敏化剂在440-500 nm内有最大吸收峰,表现出明显的电荷分离特征, INI2具有比D9染料更高的最大理论短路电流. Fukui反应指数计算指出INI2的亲核加成最易实现.染料分子在二氧化钛(101)面吸附计算表明,染料INI2以间接注入途径实现电子注入.综合计算结果,中氮茚INI染料有希望作为性能优良的染料敏化剂而得到应用.
Nine new D-π-A metal-free sensitizers INI1-INI9 with indolizino [3, 4, 5-ab] isoindole (INI) as electronic donor were investigated using the density functional theory (DFT) and time-dependent DFT calculations. Compared to D5 and D9, some major factors affecting the performance of the cell, including light harvesting, electron injection, dye regeneration, and charge recombination are taken into consideration. Calculations show that these novel INI-based sensitizers have an absorption maximum at 440-500 nm when π conjugated bridge attached at different position of aromatic ring and an excellent charge separation characters. INI2 shows better performance than that of D9 due to the theoretical maximum short-circuit current density of 13.26 mA·cm-2. Fortunately, condensed Fukui function calculation suggested that the INI2 be easiest to obtain due to a largest nucleophilic index at 2 position of INI aromatic ring. Based on the calculations of dyes adsorption on TiO2 cluster, indirect electron injection may be the main path from dye to TiO2 for INI2 and D5. Our calculations indicate that the INI dyes will be promising candidates for fabrication of the high performance dye-sensitized solar cells
Dye Sensitizers for Photodynamic Therapy  [PDF]
Alexandra B. Ormond,Harold S. Freeman
Materials , 2013, DOI: 10.3390/ma6030817
Abstract: Photofrin ? was first approved in the 1990s as a sensitizer for use in treating cancer via photodynamic therapy (PDT). Since then a wide variety of dye sensitizers have been developed and a few have been approved for PDT treatment of skin and organ cancers and skin diseases such as acne vulgaris. Porphyrinoid derivatives and precursors have been the most successful in producing requisite singlet oxygen, with Photofrin ? still remaining the most efficient sensitizer (quantum yield = 0.89) and having broad food and drug administration (FDA) approval for treatment of multiple cancer types. Other porphyrinoid compounds that have received approval from US FDA and regulatory authorities in other countries include benzoporphyrin derivative monoacid ring A (BPD-MA), meta-tetra(hydroxyphenyl)chlorin ( m-THPC), N-aspartyl chlorin e6 (NPe6), and precursors to endogenous protoporphyrin IX (PpIX): 1,5-aminolevulinic acid (ALA), methyl aminolevulinate (MAL), hexaminolevulinate (HAL). Although no non-porphyrin sensitizer has been approved for PDT applications, a small number of anthraquinone, phenothiazine, xanthene, cyanine, and curcuminoid sensitizers are under consideration and some are being evaluated in clinical trials. This review focuses on the nature of PDT, dye sensitizers that have been approved for use in PDT, and compounds that have entered or completed clinical trials as PDT sensitizers.
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