Theoretical investigation of novel carbazole-fluorene based D-π-A conjugated organic dyes as dye-sensitizer in dye-sensitized solar cells (DSCs)

The ground state structure and frontier molecular orbital of newly synthesized carbazole-fluorene based D-π-A organic dyes, CFP1A, CFP2A, CFP1CA, and CFP2CA, were theoretically investigated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. These dye molecules have been constructed based on carbazole-fluorene as the electron-donating moiety while introducing benzene units as π-spacer connected to different anchor groups, such as acrylic acid and cyanoacrylic acid, as acceptors. The electronic vertical excitation energies and absorption wavelength were carried out using time-dependent DFT (TD-DFT). Furthermore, the adsorptions of phenylacrylic acid and phenylcyanoacrylic acid on the TiO(2) anatase (101) surface were carried out by means of quantum-chemical periodic calculations employing periodic PBE functional with DNP basis set. The results promise that anchor dyes with strong withdrawing CN group have easier injected electron to the conduction band of semiconductor implying that CFP1CA and CFP2CA show better performance among four dyes. Additionally, the intramolecular charge transfers (ICT) from electron donor group to anchoring group of CFP1CA and CFP2CA have shown better performance. The calculated results provide the efficiency trend of our new dyes as CFP1CA ≈ CFP2CA > CFP1A ≈ CFP2A which are excellently agree with experimental observation.     

Molecular Design Principle of All‐organic Dyes for Dye‐Sensitized Solar Cells

All‐organic dyes have shown promising potential as an effective sensitizer in dye‐sensitized solar cells (DSSCs). The design concept of all‐organic dyes to improve light‐to‐electric‐energy conversion is discussed based on the absorption, electron injection, dye regeneration, and recombination. How the electron‐donor–acceptor‐type framework can provide better light harvesting through bandgap‐tuning and why proper arrangement of acceptor/anchoring groups within a conjugated dye frame is important in suppressing improper charge recombination in DSSCs are discussed. Separating the electron acceptor from the anchoring unit in the donor–acceptor‐type organic dye would be a promising strategy to reduce recombination and improve photocurrent generation.     

D-π-A dye system containing cyano-benzoic acid as anchoring group for dye-sensitized solar cells

A D-π-A dye (KM-1) incorporating cyano-benzoic acid as a new acceptor/anchoring group has been synthesized for dye-sensitized solar cells (DSCs) with a high molar extinction coefficient of 66,700 M(-1) cm(-1) at 437 nm. Theoretical calculations show that the hydrogen bond between -CN and surface hydroxyl leads to the most stable configuration on the surface of TiO(2). In addition, the adsorption of the dye on TiO(2) follows a Brunauer-Emmett-Teller (BET) isotherm. Multilayer adsorption of KM-1 on TiO(2) seems to take place particularly at higher dye concentrations. DSC device using KM-1 reached a maximum incident photon-to-current conversion efficiency (IPCE) of 84%, with a solar to electric power conversion efficiency (PCE) of 3.3% at AM1.5 G illumination (100 mW cm(-2)). This new type of anchoring group paves a way to design new dyes that combine good visible light harvesting with strong binding to the metal oxide surface.     

Effect of TiO2 colloids on the fluorescence behavior of two cyanine dyes

The photophysical properties of two typical cyanine dyes [3,3'-diethyl-9-methyl-thiacarbocyanine iodide (dye A) and anhydro-3,3'-disulfopropyl-5,5'-diphenyl-9-ethyloxacarbocyanine hydroxide (dye B)] in the absence and presence of TiO(2) colloids have been investigated by UV-visible spectroscopy, (1)H-NMR spectroscopy, fluorescence spectroscopy, fluorescence lifetime measurements, and ESR measurements. It was found from the absorption spectra and NMR results that there are two isomers in the ground state of these dyes. Steady-state fluorescence spectra show that the fluorescence intensities of dye A and dye B are enhanced and quenched by TiO(2) colloids, respectively. Time-resolved fluorescence lifetime measurements indicate that the lifetimes of dye A and dye B in the presence of TiO(2) colloids are longer and shorter than those obtained in the absence of TiO(2) colloids, respectively. ESR measurements demonstrate that the electron transfer efficiency from (1)dye B* to the conduction band of TiO(2) is much larger than that from (1)dye A* to the conduction band of TiO(2). The different fluorescence behavior of dye A and dye B can be intepreted in terms of whether phi(Tr,nr)(0)-phi(Tr,nr) (the reduction of the quantum yield for radiationless transition in the excited singlet state (1)dye* caused by the TiO(2) colloids) is larger or smaller than phi(ET) (the quantum yield of electron transfer from (1)dye* to the conduction band of TiO(2) colloids).     

Change of adsorption modes of dyes on fluorinated TiO2 and its effect on photocatalytic degradation of dyes under visible irradiation

Surface-fluorinated TiO2 (F-TiO2) particles were prepared via the HF etching method. The surface characteristics of fluorinated TiO2, the adsorption modes of dyes, and the reaction pathways for the photocatalytic degradation of dye pollutants under visible light irradiation were investigated. It was found that, in the treatment of TiO2 by HF etching, F(-) not only displaces surface HO(-) but also substitutes some surface lattice oxygen. Using zwitterionic Rhodamine B (RhB) dye as a model, the change of the adsorption mode of RhB on F-TiO2 relative to that on pure TiO2 was validated by adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and IR techniques for the first time. RhB preferentially anchors on pure TiO2 through the carboxylic (-COOH) group, while its adsorption group is switched to the cationic moiety (-NEt 2 group) on F-TiO2. Both the photocatalytic degradation kinetics and mechanisms were drastically changed after surface fluorination. Dyes with positively charged nitrogen-alkyl groups such as methylene blue (MB), malachite green (MG), Rhodamine 6G (Rh6G), and RhB all underwent a rapid N-dealkylation process on F-TiO2, while on pure TiO2 direct cleavage of dye chromophore ring structures predominated. The relationship between surface fluorination and the degradation rate/pathway of dyes under visible irradiation was also discussed in terms of the effect of fluorination on the surface adsorption of dyes and on the energy band structure of TiO2.     

Photocatalytic reactivities of Nafion-coated TiO2 for the degradation of charged organic compounds under UV or visible light

Nafion (perfluorinated polymer with sulfonate groups)-coated TiO2 particles (Nf/TiO2) were prepared and their reactivities for the photocatalytic degradation (PCD) of charged organic substrates were investigated. The presence of Nafion adlayers drastically changed the positive TiO2 surface charge to a negative one over the entire pH range and significantly influenced the PCD kinetics and mechanisms. The UV-induced PCD of tetramethylammonium (TMA; cationic substrate) was greatly enhanced in the presence of Nafion adlayers on TiO2 because the ion-exchange sites within the Nafion can hold cationic substrates. On the other hand, despite the unfavorable electrostatic interaction between the Nf/TiO2 and anionic substrates, the PCD of dichloroacetate (DCA) and acid orange 7 (AO7) with Nf/TiO2 was not significantly inhibited. The visible-light-sensitized degradation of dyes was enhanced with Nf/TiO2 not only for cationic dyes (methylene blue (MB) and rhodamine B (RhB)) whose uptake on Nf/TiO2 is enhanced, but also for an anionic dye (AO7) that is less adsorbed on Nf/TiO2. The unexpected behavior in AO7 degradation seems to be related to the role of the Nafion layer in retarding the charge recombination. These observations indicate that Nf/TiO2 can enhance the PCD reactivity for cationic substrates without sacrificing the PCD reactivity for anionic substrates. In addition, it was found that the sensitized degradation of RhB followed a different path when the surface of TiO2 was coated with Nafion. The N-de-ethylation of RhB that leads to the generation of rhodamine-110 was a prevailing path with Nf/TiO2, whereas the cleavage of the chromophoric ring structure was dominant with pure TiO2. The effects of Nafion adlayers on the photoinduced electron transfer and PCD kinetics and mechanisms are discussed.     

New Dual Donor–Acceptor (2D‐π‐2A) Porphyrin Sensitizers for Stable and Cost‐Effective Dye‐Sensitized Solar Cells

A series of porphyrin sensitizers that featured two electron‐donating groups and dual anchoring groups that were connected through a porphine π‐bridging unit have been synthesized and successfully applied in dye‐sensitized solar cells (DSSCs). The presence of electron‐donating groups had a significant influence on their spectroscopic, electrochemical, and photovoltaic properties. Overall, the dual anchoring groups gave tunable electronic properties and stronger attachment to TiO₂. These new dyes were readily synthesized in a minimum number of steps in gram‐scale quantities. Optical and electrochemical data confirmed the advantages of these dyes for use as sensitizers in DSSCs. Porphyrins with electron‐donating amino moieties provided improved charge separation and better charge‐injection efficiencies for the studied dual‐push–pull dyes. Attenuated total reflectance–Fourier‐transform infrared (ATR‐FTIR) and X‐ray photoelectron spectroscopy of the porphyrin dyes on TiO₂ suggest that both p‐carboxyphenyl groups are attached onto TiO₂, thereby resulting in strong attachment. Among these dyes, cis-Zn2BC2A , with two electron‐donating 3,6‐ditertbutyl‐phenyl‐carbazole groups and dual‐anchoring p‐carboxyphenyl groups, showed the highest efficiency of 4.07 %, with J_SC=9.81 mA cm^?2, V_OC=0.63 V, and FF=66 %. Our results also indicated a better photostability of the studied dual‐anchored sensitizers compared to their mono‐anchored analogues under identical conditions. These results provide insight into the developments of a new generation of high‐efficiency and thermally stable porphyrin sensitizers.     

苯并噻二唑衍生物作为铆接基团提高染料敏化太阳能电池效率

This work describes the characteristics of benzobisthiadiazole analogues with different heteroatom substitution patterns as electronwithdrawing anchoring groups in dye-sensitized solar cells (DSSCs). In order to provide a systematic analysis of the effect of the designed anchoring groups, the widely used anchor cyanoacrylic acid was used as the reference. Theoretical calculations show that the newly designed anchors are capable of displaying a decent level of light absorption covering the entire visible range up to the near-IR region of 1000 nm. More importantly, an ultrafast electron injection is observed from the dyes SPN and SPS into the TiO₂ surface. The quantum dynamics of the interfacial electron transfer (IET) reveal that SPN and SPS anchors provide efficient IET performance. About 90% of the electron injection occurs in the first 15 fs, and is complete after ~100 fs. Furthermore, the pathway of electron injection is direct, leading to very efficient transfer of the wavepacket through the TiO₂ semiconductor. Therefore, the performances of both the anchors, SPN and SPS, are equivalent and even superior to that of cyanoacrylic acid. These findings are important in the context of providing guidelines for the design of metal-free organic dye sensitizers for high efficient DSSCs.     

Comparison of interfacial electron transfer through carboxylate and phosphonate anchoring groups

The effects of anchoring groups on electron injection from adsorbate to nanocrystalline thin films were investigated by comparing injection kinetics through carboxylate versus phosphonate groups to TiO2 and SnO2. In the first pair of molecules, Re(LA)(CO)3Cl (ReC1A) and Re(Lp)(CO)3Cl (ReC1P), [LA=2,2'-bipyridine-4,4'-bis-CH2-COOH, Lp=2,2'-bipyridine-4,4'-bis-CH2-PO3H2], the anchoring groups were insulated from the bipyridine ligand by a CH2 group. In the second pair of molecules, Ru(dcbpyH2)2(NCS)2 (RuN3) and Ru(bpbpyH2)2(NCS)2 (RuN3P), [dcbpy=2,2'-bipyridine-4,4'-biscarboxylic acid, bpbpy=2,2'-bipyridine-4,4'-bisphosphonic acid], the anchoring groups were directly connected to the bipyridine ligands. The injection kinetics, as measured by subpicosecond IR absorption spectroscopy, showed that electron injection rates from ReC1P to both TiO2 and SnO2 were faster than those from ReC1A. The injection rates from RuN3 and RuN3P to SnO2 films were similar. On TiO2, the injection kinetics from RuN3 and RuN3P were biphasic: carboxylate group enhances the rate of the <100 fs component, but reduces the rate of the slower components. To provide insight into the effect of the anchoring groups, the electronic structures of Re-bipyridyl-Ti model clusters containing carboxylate and phosphonate anchoring groups and with and without a CH2 spacer were computed using density functional theory. With the CH2 spacer, the phosphonate group led to a stronger electronic coupling between bpy and Ti center than the carboxylate group, which accounted for the faster injection from ReC1P than ReC1A. When the anchoring groups were directly connected to the bpy ligand without the CH2 spacer, such as in RuN3 and RuN3P, their effects were 2-fold: the carboxylate group enhanced the electronic coupling of bpy pi* with TiO2 and lowered the energy of the bpy orbital. How these competing factors led to different effects on TiO2 and SnO2 and on different components of the biphasic injection kinetics were discussed.     

二氢吲哚类染料用于染料敏化太阳能电池光敏剂的比较

采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)对四种二氢吲哚染料进行研究, 从中筛选出相对优秀的染料敏化太阳能电池光敏剂. 对前线分子轨道的计算表明, 二氢吲哚染料的前线分子轨道结构非常有利于染料激发态向TiO2电极的电子注入. 对真空中的紫外和可见光吸收光谱的计算表明, 二氢吲哚染料的吸收光谱与太阳辐射光谱匹配较好. 对染料分子的能级计算表明, 二氢吲哚染料的能级结构比较适合于I-/I-3作电解液的TiO2纳米晶太阳能电池的光敏剂. 二氢吲哚染料最低未占据分子轨道(LUMO) 能级均比TiO2晶体导带边能级高, 能够保证激发态染料分子高效地向TiO2电极转移电子. 二氢吲哚染料最高占据分子轨道(HOMO)的能级比I-/I-3能级低, 保证了失去电子的染料分子能够顺利地从电解液中得到电子. 与实验数据比较, 得出在提高染料敏化太阳能电池转换效率方面, 对染料的关键要求是LUMO能级的位置. 染料分子的稳定性是染料敏化太阳能电池使用寿命的关键因素. 通过对化学键键长的比较表明, 二氢吲哚染料的分子稳定性基本相同. 对计算结果的分析表明, 二氢吲哚染料1(ID1)的LUMO能级最高, 分子稳定性最好, 在酒精溶液中的吸收光谱与太阳辐射光谱匹配很好, 在同类染料中是较好的染料敏化太阳能电池光敏剂.     

Dye-sensitized solar cells based on donor-π-acceptor fluorescent dyes with a pyridine ring as an electron-withdrawing-injecting anchoring group

A new‐type of donor–acceptor π‐conjugated (D‐π‐A) fluorescent dyes NI3 – NI8 with a pyridine ring as electron‐withdrawing‐injecting anchoring group have been developed and their photovoltaic performances in dye‐sensitized solar cells (DSSCs) are investigated. The short‐circuit photocurrent densities and solar energy‐to‐electricity conversion yields of DSSCs based on NI3 – NI8 are greater than those for the conventional D‐π‐A dye sensitizers NI1 and NI2 with a carboxyl group as the electron‐withdrawing anchoring group. The IR spectra of NI3 – NI8 adsorbed on TiO₂ indicate the formation of coordinate bonds between the pyridine ring of dyes NI3 – NI8 and the Lewis acid sites (exposed Tiⁿ⁺ cations) of the TiO₂ surface. This work demonstrates that the pyridine rings of D‐π‐A dye sensitizers that form a coordinate bond with the Lewis acid site of a TiO₂ surface are promising candidates as not only electron‐withdrawing anchoring group but also electron‐injecting group, rather than the carboxyl groups of the conventional D‐π‐A dye sensitizers that form an ester linkage with the Brønsted acid sites of the TiO₂ surface.     

Porphyrins for dye-sensitised solar cells: new insights into efficiency-determining electron transfer steps

Porphyrin molecules offer immense potential as the light harvesting component of dye-sensitised nanocrystalline TiO(2) solar cells. Synthetic porphyrin dyes were amongst the first dyes trialled for sensitisation of inorganic semiconducting oxides. Today, they exhibit the best performance reported for dye-sensitised solar cells. Accompanying the significant performance improvement over the last two decades is a much improved understanding of efficiency-determining fundamental electron transfer steps, from charge photogeneration to recombination. In this feature article we highlight our recent discoveries of the influence of porphyrin molecule structure on efficiency determining electron transfer kinetics and device performance by systematically changing the molecular structure and observing electron injection and recombination kinetics using time-resolved optical and electrical probes. Despite our observation of ultrafast charge injection for all porphyrin dyes studied by transient absorption spectroscopy, the injection yield estimated using an internal standard remains below 100% and depends strongly on the molecular structure. The observed discrepancy between kinetic competition and the injection yield is attributed to non-injecting dyes, probably arising due to inhomogeneity. A very interesting sub-ns (0.5 ns to 100 ns) charge recombination channel between photo-injected electrons and porphyrin cations is observed, which is found to be more prominent in free-base porphyrin dyes with a conjugated linker. Charge recombination between the acceptor species in the redox containing electrolyte and injected electrons is shown to be an important limitation of most porphyrin-sensitised solar cells, accelerated by the presence of porphyrin molecules at the TiO(2)-electrolyte interface. This recombination reaction is strongly dependent on the porphyrin molecular structure. Bulky substituents, using a porphyrin dimer instead of a porphyrin monomer, a light soaking treatment of freshly prepared films and co-sensitization of TiO(2) with multiple dyes are shown to be successful strategies to improve electron lifetime. Finally, new developments unique to porphyrin dye-sensitised solar cells, including performance enhancements from a light exposure treatment of a zinc porphyrin dye, a significant performance improvement observed after co-sensitisation of TiO(2) with free-base and zinc porphyrin dyes and the use of porphyrin dimers with increased light harvesting in thin-film TiO(2) solar cells are described.     

三苯胺功能染料的合成及在谷胱甘肽超低电位光电检测中的应用

设计合成了一种具有D-π-A结构的三苯胺功能染料(TCA),并通过分子结构中的羧基将其配位于TiO_2纳米粒子修饰的光电极表面,发展了一种可在超低电位下高灵敏检测谷胱甘肽(GSH)的光电传感方法.该TCA分子以三苯胺为电子给体,噻吩为桥连基团,氰基乙酸为电子受体.在可见光的照射下,TCA通过分子内电子转移将光电子由三苯胺经噻吩和羧基注入到TiO_2的导带能级,进而注入基底光电极,产生阳极光电流;同时,TCA被氧化到氧化态.由于氧化态TCA的稳定性好,可循环被生理活性小分子GSH还原,并产生放大的阳极光电流.TCA功能化的TiO_2纳米粒子修饰电极对GSH表现出了极高的催化活性,在波长为480 nm的可见光照射下,在0 V的超低电位下即可实现对GSH的催化氧化.基于这一性质,发展了一种可用于GSH检测的光电传感方法.在最优条件下,该传感器对浓度为2~100μmol/L和0.1~2.4 mmol/L的GSH具有良好的线性响应,检出限低达1μmol/L.此外,该光电传感器具有较好的选择性,可排除13种氨基酸和生理活性物质多巴胺及氢醌的干扰,因此具有一定的实际应用前景.     

Dye-sensitized solar cells based on functionalized truxene structure

Three new metal-free organic dyes(TX1, TX2 and TX3) based on truxene core structure, with triphenylamine as the electron donor, thiophene as the p spacers, and cyanoacetic acid or rhodanine-3-acetic acid as the electron acceptor are designed and synthesized. Their UV–vis absorption spectra,electrochemical and photovoltaic properties were investigated. The cyanoacrylic acid is verified to be a better acceptor unit(meanwhile the anchoring group) compared to the rhodanine-3-acetic acid. And also, two anchoring groups in TX2 could provide stronger adsorption ability on the Ti O2 surface. In addition, the EIS results indicate a slower charge recombination processes for TX2. As a result, dye TX2 bearing two cyanoacetic acid outperforms the other two dyes, exhibiting the photo-conversion efficiency of 2.64%, with Jsc= 5.09 m A cm–2, Voc= 729 m V, FF = 71.1.     

Characterization of the adsorption of Ru-bpy dyes on mesoporous TiO2 films with UV-Vis, Raman, and FTIR spectroscopies

In the present work the adsorption of a new dye, [Ru(dcbpyH(2))(2)(bpy-TPA(2))](PF(6))(2), and the well-known (Bu(4)N)(2)[Ru(dcbpyH)(2)(NCS)(2)] complex on mesoporous anatase films were investigated to clarify the role of the carboxylate groups in the anchoring process of the dyes on the semiconductor surface. For this purpose UV-vis, Raman, resonance Raman, and ATR-FTIR spectroscopies have been used. The results of the Raman experiments at different excitation wavelengths demonstrate that photoinduced charge-transfer processes take place efficiently between the adsorbate and the substrate. Moreover, this is the first time that the Raman spectrum of a Ru-bpy dye (in this case, the dye N719) adsorbed on TiO(2) has been obtained without the resonance condition, only by means of SERS enhancement. The coordination of both complexes on the TiO(2) paste films is proposed to occur via bidentate or bridging linkage.     

Electrophoretic deposition of TiO2 nanoparticles using organic dyes

Electrophoretic deposition method has been developed for the deposition of TiO(2) nanoparticles modified with organic dyes. Alizarin red, alizarin yellow and pyrocatechol violet dyes were used for the dispersion and charging of TiO(2) in ethanol and anodic electrophoretic deposition of TiO(2) films. The deposition yield was varied by the variation of dye concentration in suspensions and deposition time. Aurintricarboxylic acid dye was used for the deposition of TiO(2) from aqueous suspensions. It was found that thin films of pure aurintricarboxylic acid and composite aurintricarboxylic acid TiO(2) films can be obtained. The deposition yield was studied by quartz crystal microbalance. Dye film thickness was varied in the range of 0.1-2 μm by variation in the deposition time at a constant voltage. The composition of the films and the amount of the deposited material can be varied by the variation of TiO(2) and dye concentration in suspensions and deposition time. The films were studied by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis and electron microscopy. The deposition mechanisms were discussed. The electrophoretic deposition method offers advantages for the fabrication of dye-sensitized TiO(2) films.     

Convenient photooxidation of alcohols using dye sensitised semiconductors in combination with silver nitrate and TEMPO--an electron paramagnetic resonance study

A mechanistic investigation into the photooxidation of alcohols using dye sensitised titanium dioxide and dye sensitised zinc oxide is described. The varying yields using the two photocatalysts have been explained using electron paramagnetic resonance (EPR) spectroscopy, which indicated that electron injection occurs in the dye sensitised ZnO system but is sluggish in the dye sensitised TiO(2) system. Due to the failure of the electron injection step, a 'break' in the photooxidative system occurs resulting in a decrease in the conversion of benzyl alcohol to benzaldehyde for the dye sensitised TiO(2) system.     

High-Performance Dipolar Organic Dyes with an Electron-Deficient Diphenylquinoxaline Moiety in the π-Conjugation Framework for Dye-Sensitized Solar Cells

We report here the synthesis and electrochemical and photophysical properties of a series of easily prepared dipolar organic dyes and their application in dye-sensitized solar cells (DSSCs). For the six organic dyes, the molecular structures comprised a triphenylamine group as an electron donor, a cyanoacrylic acid as an electron acceptor, and an electron-deficient diphenylquinoxaline moiety integrated in the π-conjugated spacer between the electron donor and acceptor moieties. The incorporation of the electron-deficient diphenylquinoxaline moiety effectively reduces the energy gap of the dyes and broadly extends the spectral coverage. DSSCs based on dye 6 produced the best overall cell performance of 7.35?%, which translates to approximately 79?% of the intrinsic efficiency of the DSSCs based on the standard N719 dye under identical experimental conditions. The high performance of DSSCs based on dye 6 among the six dyes explored is attributed to the combined effects of high dye loading on a TiO(2) surface, rapid dye regeneration, and effective retardation of charge recombination.     

A comparison of H+-restacked nanosheets and nano-scrolls derived from K4Nb6O17for visible-light degra-dation of dyes

H＋-restacked nanosheets and nanoscrolls peeled from K4Nb6O17 display different structures and surface characters. The two restacked samples with increased surface areas have an amazing visible-light response for the photodegradation of dyes, which is superior to commercial TiO2 （P25） and Nb205. By comparison, H＋/nanosheets have a relatively faster photodegradation rate originated from large and smooth basal plane. The work reveals that dye adsorbed on the unfolded nanosheets can effectively harvest sunlight. Due to facile preparation, low-cost and high photocatalytic efficiency, H＋/nanosheets and H＋/nanoscrolls might be used for the visible light-driven degradation of organic dyes as a substitute for TiO2 in industry.     

Sensitizer molecular structure-device efficiency relationship in dye sensitized solar cells

In the Dye Sensitized Solar Cell (DSSC) the dye sensitizer carries out the light harvesting function and is therefore crucial in determining overall cell efficiency. In addition, the dye sensitizer can influence many of the key electron transfer processes occurring at the TiO(2)/dye/electrolyte interface which also determine efficiency. Dye structure can influence and drive forward electron injection into the conduction band of the TiO(2). Conversely, dye structure can help retard loss electron transfer processes such as charge recombination of injected electrons in the TiO(2) with dye cations and also recombination of these electrons with the electrolyte. Therefore tuning dye sensitizer light absorbing properties and control of the aforementioned electron transfer processes through structural design of the dye sensitizer is an important avenue through which optimization of DSSC efficiency should be pursued. In this critical review the latest work focusing on the design of dyes for efficient DSSCs is revised (111 references).