香豆素型染料敏化剂的合成及光电性能研究

选择带有供电子基团的香豆素作为给体,噻吩基作为桥键,氰乙酸为受体,合成了两种新的具有"D-π-A"结构的香豆素型染料敏化剂,对其光谱性能、电化学性能以及光电转换性能进行了测试.结果表明,两者分子轨道能级与TiO2电极的导带以及电解质I2/I-的氧化还原电位相匹配,保证了电池电流循环的顺利产生.与甲氧基取代的染料敏化剂2-氰基-3-[5-(7-甲氧基-2-羰基-2H-苯并吡喃-3-基)噻吩-2-基]丙烯酸(IIIb)相比,香豆素环7位上二乙氨基取代的染料敏化剂2-氰基-3-[5-(7-二乙胺基-2-羰基-2H-苯并吡喃-3-基)噻吩-2-基]丙烯酸(IIIa)分子内电荷转移吸收较强,紫外吸收光谱红移.IIIa组装得到的染料敏化太阳能电池暗电流降低,具有较高的单色光转化效率IPCE(incident photo-to-currentconversion efficient)和短路电流Jsc,从而具有较高的光电转换效率(Jsc=8.68 mA/cm2,Voc=574 mV,η=3.52%).     

具有推拉电子结构卟啉染料的合成及其在染料敏化太阳能电池中的应用

将N,N’-二-(9,9’-二己基芴)胺作为电子供体引入具有推拉电子结构的卟啉染料中,设计合成了2个新的染料敏化太阳能电池(DSSCs)敏化剂WP-1和WP-2。利用核磁共振氢谱和高分辨质谱对染料结构进行了表征。测试了染料的紫外-可见吸收光谱。将其应用于染料敏化太阳能电池中,在模拟太阳光(100×10-3W/cm2)照射下,染料WP-1和WP-2敏化电池的能量转换效率分别达到了4.01%和7.07%。WP-2敏化的电池封装后经自然光照射500 h后,光电效率仍能维持在初始效率的98%以上。说明N,N’-二-(9,9’-二己基芴)胺作为电子供体,很适合推拉电子结构的卟啉染料。不仅丰富了用于卟啉染料的电子供体的种类,也为进一步将二芴胺衍生物引入到卟啉染料中的研究奠定了基础。     

基于不同取代基的噻吩-三苯胺染料敏化剂的合成与光伏性能

本文合成了含3种不同取代基的噻吩-三苯胺染料敏化剂(H1,H2和H3),并将其应用于二氧化钛纳米晶染料敏化太阳能电池.系统地研究了3种染料的光物理、电化学和光伏性能.基于H1的染料敏化太阳能电池获得了9.10%的光电转换效率(Voc=0.72V,Jsc=18.03mAcm-2,FF=0.70).     

不同受体结构染料共敏化对染料敏化太阳电池性能的影响（英文）

为了拓宽染料敏化太阳电池对太阳光谱的响应范围,提高电池的光电转换效率,将两种含有不同受体结构(绕丹宁-3-乙酸基(RA)和氰基丙烯酸基(CA))的三苯胺染料(TR1和TC1)进行共敏化。TR1染料平伏吸附在TiO_2表面,而TC1染料直立吸附在TiO_2表面。将两种染料按照不同摩尔比共敏化TiO_2后,TC1占据TR1的部分位置,拓展光谱的同时也抑制了电荷复合,电子寿命较TR1敏化的太阳电池长。在TR1与TC1摩尔比为5∶5的共敏剂溶液敏化的共敏电池器件中,短路光电流密度(J_(sc))为11.7 mA/cm~2,开路电压(V_(oc))为704 mV,填充因子(FF)为0.73,光电转换效率(η)为6.03%。该结果明显优于单一染料敏化的电池器件。     

π桥中不同吸电子基团对三苯胺-氰基丙烯酸类染料敏化太阳能电池性能影响的理论研究

采用密度泛函理论和含时密度泛函理论计算了染料的紫外-可见吸收光谱、电子注入驱动力、半导体导带能级移动量以及染料与碘的相互作用能等一系列评价电池性能的理论参数,以解释在π桥上引入不同吸电子基团导致三苯胺-氰基丙烯酸基染料敏化太阳能电池光电转换效率降低的原因.结果表明,在染料π桥上引入吸电子基团虽可以在一定程度上改善吸收光谱,但同时也引入了额外的与电解质中碘相互作用的位点,加快了与电解质之间的复合速率,影响了电子注入驱动力,最终导致电池光电转换效率降低.因此,在设计高效光敏染料时除了考虑吸收光谱外,也应考虑染料与电解质之间的复合以及电子注入驱动力这2个影响电池性能的关键因素.     

不同受体结构染料共敏化对染料敏化太阳电池性能的影响

为了拓宽染料敏化太阳电池对太阳光谱的响应范围,提高电池的光电转换效率,将两种含有不同受体结构（绕丹宁-3-乙酸基（RA）和氰基丙烯酸基（CA））的三苯胺染料（TR1和TC1）进行共敏化。TR1染料平伏吸附在TiO₂表面,而TC1染料直立吸附在TiO₂表面。将两种染料按照不同摩尔比共敏化TiO₂后,TC1占据TR1的部分位置,拓展光谱的同时也抑制了电荷复合,电子寿命较TR1敏化的太阳电池长。在TR1与TC1摩尔比为5：5的共敏剂溶液敏化的共敏电池器件中,短路光电流密度（J_sc）为11.7 mA/cm²,开路电压（V_oc）为704 mV,填充因子（FF）为0.73,光电转换效率（η）为6.03%。该结果明显优于单一染料敏化的电池器件。     

两种菁类染料复合敏化TiO_2纳米晶电极的光电化学研究

应用光电化学方法研究了两种菁类染料Cy3和Cy5复合敏化TiO2纳米晶电极的光电化学行为.结合两种染料的紫外-可见光谱和循环伏安曲线,确定了Cy3和Cy5的电子基态和激发态能级位置.结果表明两种染料的激发态能级位置能与TiO2纳米粒子导带边位置相匹配,复合敏化可以显著提高TiO2纳米晶的光电流,使TiO2纳米晶电极吸收波长由紫外光区红移至可见光区和近红外区.复合敏化降低了染料Cy3 在电极吸附时的聚集程度,使其单色光的转换效率(IPCE)提高了169%,复合敏化电极总的光电转换效率η为2.09%,分别是Cy3和Cy5单独敏化时光电转换效率的2.069 和1.229倍.     

两种菁类染料复合敏化TiO2纳米晶电极的光电化学研究

应用光电化学方法研究了两种菁类染料Cy3和Cy5复合敏化TiO2纳米晶电极的光电化学行为. 结合两种染料的紫外-可见光谱和循环伏安曲线, 确定了Cy3和Cy5的电子基态和激发态能级位置. 结果表明两种染料的激发态能级位置能与TiO2纳米粒子导带边位置相匹配, 复合敏化可以显著提高TiO2纳米晶的光电流, 使TiO2纳米晶电极吸收波长由紫外光区红移至可见光区和近红外区. 复合敏化降低了染料Cy3在电极吸附时的聚集程度, 使其单色光的转换效率(IPCE)提高了169%, 复合敏化电极总的光电转换效率η为2.09%, 分别是Cy3和Cy5单独敏化时光电转换效率的2.069和1.229倍.     

双链结构有机光敏染料的合成及性能

设计合成了2个含双D-π-A结构的新型有机光敏染料DP1和DP2,利用高分辨质谱(HRMS)、核磁共振氢谱及核磁共振碳谱对其结构进行了表征。 研究了2个染料的光物理和电化学性质,并将其应用于染料敏化太阳能电池(DSSCs)的制作中。 在100×10-3 W/cm2(AM 1.5) 模拟太阳光的照射下,由染料DP2所制备的敏化太阳能电池的光电转化效率为4.10%;开路电压(Voc)、短路电流密度(Jsc)和填充因子(FF)分别为0.63 V、8.59×10-3 A/cm2和0.76。 而在同等条件下,由染料DP1所制作的染料敏化电池光电转化效率为3.83%。     

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.     

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.     

Computational modelling of TiO2 surfaces sensitized by organic dyes with different anchoring groups: adsorption modes, electronic structure and implication for electron injection/recombination

We present a Density Functional Theory investigation aimed to model the possible adsorption modes to the TiO(2) surface of two representative TPA-based dyes, termed L0 and rh-L0, having the two mostly employed anchoring groups, namely the cyanoacrylic and rhodanine-3-acetic acids respectively. The bidentate coordination with proton transfer to a nearby surface oxygen is found to be the energetically favored anchoring mode for both dyes. The calculations show that the different dye anchoring groups give rise to a very different electronic coupling between the dye and the manifold of unoccupied semiconductor states, thus implying different electron injection mechanisms. The strongly coupled L0 dye possibly shows an adiabatic electron injection mechanism, while a non-adiabatic electron injection can be foreseen for the weakly coupled rh-L0 dye. The different orientation with respect to the TiO(2) surface for the two classes of dyes, implying different distances of the donor group from the oxide surface, together with the different electron injection mechanisms might account for the faster recombination reaction measured for the rhodanine-based dyes.     

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.     

Fine Tuning the Performance of DSSCs by Variation of the π‐Spacers in Organic Dyes that Contain a 2,7‐Diaminofluorene Donor

Organic dyes that contain a 2,7‐diaminofluorene‐based donor, a cyanoacrylic‐acid acceptor, and various aromatic conjugation segments, which are composed of benzene, fluorene, carbazole, and thiophene units, as a π‐bridge have been synthesized and characterized by optical, electrochemical, and theoretical investigations. The trends in the absorption and electrochemical properties of these dyes are in accordance with the electron‐donating ability of the conjugating segment. Consequently, the dyes that contained a 2,7‐carbazole unit in the π‐spacer exhibited red‐shifted absorption and lower oxidation potentials than their corresponding fluorene‐ and phenylene‐bridged dyes. However, the enhanced power‐conversion efficiency that was exhibited by the fluorene‐bridged dyes in the DSSCs was attributed to their broader and intense absorption. Despite the longer‐wavelength absorption and reasonable optical density, carbazole‐bridged dyes exhibited lower power‐conversion efficiencies, which were ascribed to the poor alignment of the LUMO level in these dyes, thereby leading to the inhibition of electron injection into the TiO₂ conduction band.     

Electrochemical behavior of tryptophan and its derivatives at a glassy carbon electrode modified with hemin

The electrochemical behavior of tryptophan (Trp) and its derivatives, such as indole-3-acetic acid (IAA), 5-hydroxytryptamine (5-HT), 5-hydroxy-indole-3-acetic acid (5-HIAA) and glycyl-tryptophan (Gly-Trp) peptide at a glassy carbon electrode modified with hemin (hemin/GC electrode) by electropolymerization have been investigated in detail. The results showed that the hemin/GC electrode would catalyze the electrochemical oxidation of Trp and its derivatives, based on which a differential pulse voltammetric procedure has been proposed for determination of Trp and its derivatives. Meanwhile, the electrochemical reaction mechanism for these compounds at hemin/GC electrode has been also investigated, and the results indicated that a two electron and two proton transfer was involved in the electrode reaction process.     

Synthesis,optical, and electrochemical properties,and theoretical calculations of BODIPY containing triphenylamine

The boron dipyrromethene (BODIPY) triads consisting of two triphenylamine units as electron donor (D) and BODIPY core as electron acceptor (A; B3 , and B4 ) have been synthesized using facile palladium cross‐coupling reactions to broaden the absorption of the BODIPY dyes. All dyes and intermediates were characterized by ¹H NMR, ¹¹B NMR, ¹³C NMR, and ¹⁹F NMR spectroscopies, UV–Vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and time‐dependent density functional theory calculations. It was found that an increase in conjugation to the BODIPY core systematically extended the absorption and emission wavelength maxima. As a consequence, B4 containing the D–π–A–π–D structure, exhibited the longest absorption and emission maxima at 597 and 700 nm, respectively, with 1.8 eV in optical bandgap. The 96 nm red‐shifted absorption of B4 as compared to the unsubstituted BODIPY ( B1 ) indicated the effective electronic communication between triphenylamine and BODIPY. This suggested that the proper alignment of triphenylamine and BODIPY triad could lead to broader absorption and suitable low energy bandgap. Furthermore, the molecular modeling has been employed to analyze the electronic and optical properties of the dyes. We found that the optical, electrochemical, and theoretical bandgaps of all dyes were in good agreement.     

Bi‐anchoring Organic Dyes that Contain Benzimidazole Branches for Dye‐Sensitized Solar Cells: Effects of π Spacer and Peripheral Donor Groups

Benzimidazole‐branched bi‐anchoring organic dyes that contained triphenylamine/phenothiazine donors, 2‐cyanoacrylic acid acceptors, and various π linkers were synthesized and examined as sensitizers for dye‐sensitized solar cells. The structure–activity relationships in these dyes were systematically investigated by using absorption spectroscopy, cyclic voltammetry, and density functional theory calculations. The wavelength of the absorption peak was more‐heavily influenced by the nature of the π linker than by the nature of the donor. For a given donor, the absorption maximum (λ_max) was red‐shifted on changing the π linker from phenyl to 2,2′‐bithiophene, whilst the dyes that contained triphenylamine units displayed higher molar extinction coefficients (?) than their analogous phenothiazine‐based triphenylamine dyes, which led to good light‐harvesting properties in the triphenylamine‐based dyes. Electrochemical data for the dyes indicated that the triphenylamine‐based dyes possessed relatively low‐lying HOMOs, which could be beneficial for suppressing back electron transfer from the conduction band of TiO₂ to the oxidized dyes, owing to facile regeneration of the oxidized dye by the electrolyte. The best performance in the DSSCs was observed for a dye that possessed a triphenylamine donor and 2,2′‐bithiophene π linkers. Electron impedance spectroscopy (EIS) studies revealed that the use of triphenylamine as the donor and phenyl or 2,2′‐bithiophene as the π linkers was beneficial for disrupting the dark current and charge‐recombination kinetics, which led to a long electron lifetime of the injected electrons in the conduction band of TiO₂.     

Donor-acceptor organic sensitizers assembled with isoxazole or its derivative 3-oxopropanenitrile

A series of new donor-acceptor organic sensitizers LJ5-LJ7 assembled with isoxazole or its derivative 3-oxopropanenitrile was synthesized and used in dye-sensitized solar cells to study the effect of both π-spacers and anchoring groups on device performance. X-ray crystal structure analyses show planar arrangement of dithiophene and isoxazole fragments, providing an excellent π conjugation and hence the large electronic coupling between the triphenylamine donor and electron acceptor units. For the DSSC applications, the derived photophysical and photovoltaic properties revealed a lower η value of 1.06% (LJ7) and 2.41% (LJ5), and 3.30% (LJ7) for the dyes with rhodanine-3-acetic acid, cyanoacetyl group, and vinyl cyanoacetic acid as the anchor. Electrochemical impedance spectroscopy was used to determine the interfacial charge transfer process occurring in solar cells that employed different dyes.     

Synthesis,Spectral, Electrochemical and Photovoltaic Studies of A3B Porphyrinic Dyes having Peripheral Donors

Three new ‘push-pull’ A₃B Zn(II)porphyrin dyes having meso-pyrenyl, carbazolyl and phenothiazine as electron donors ( A ) and phenylcarboxylic acid as acceptor/anchor ( B ) were synthesized and utilized for DSSC application. The spectral and electrochemical redox properties of these new dyes were studied and compared with trans-A₂BC Zn(II) porphyrin dyes under similar experimental conditions. Red-shifted, broadened absorption peaks, lower fluorescence quantum yields, and shortened lifetimes were observed for the A₃B dyes as compared to zinc tetraphenylporphyrin control, ZnTPP. DFT optimized structures suggested effective charge separation related to enhanced charge injection efficiency. Driving force for electron injection (ΔG_inj) and dye regeneration (ΔG_reg) calculated from the spectral and electrochemical studies predicted facile electron injection from excited dye into semiconductor TiO₂ in the constructed solar cells. Phenothiazine appended dye ( KP - TriPTZ - Zn ) showed the highest η value of 7.3 % for PCE with greater J_sc and V_oc values due to its better light harvesting ability and reduced dye aggregation as compared to other dyes. Our studies demonstrate that the dyes having multiple electron-donating groups exhibit higher photon-to-current conversion efficiency.