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Indoline and benzothiazole-based squaraine dye-sensitized solar cells containing bis-pendent sulfonate groups: Synthesis, characterization and solar cell performance
摘要： Two new symmetric squaraine sensitizers (SQTHZ and SQIND) carrying benzothiazole and indoline moieties as strong electron donating groups to inject the electron into the TiO2 nanoparticles were tested as DSSC. The theoretical calculations and absorption results show that the electron density of LUMO of SQTHZ is delocalized in the whole chromophore, leading to strong electronic coupling between SQTHZ sensitizer and the conduction band of TiO2. Furthermore, the presence of long alkyl chain with pendent bis-SO3- groups would inhibit recombination and decrease the dye aggregation. Interestingly, SQTHZ displayed UV-Vis and NIR absorption at a longer wavelength compared to SQIND. This structure feature, as well as optical properties, would lead to improved efficiency of dye-sensitized solar cell with overall better photovoltaic performance (η of 3.31 %, Jsc of 7.65 mA/ cm2, Voc of 0.59, ff of 0.71 and IPCE of 47 % at 674 nm) compared to SQIND.
关键词： Photoelectrochemical properties,DFT,Dye-sensitized solar cell,Symmetric squaraine dyes
更新于2025-11-19 16:46:39
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π-Extended <i>cis</i> -Configured Unsymmetrical Squaraine Dyes for Dye-sensitized Solar Cells: Panchromatic Response
摘要： Light absorbing sensitizer is the heart of the third generation photovoltaic technologies such as dye-sensitized solar cells (DSSC). Despite possessing large extinction coefficients for the metal free organic dyes, the light harvesting efficiency is limited with the narrow absorption profile in either visible or NIR regions of the solar spectrum. Though monolayer formation of organic sensitizers on semiconducting metal oxide surface leads to dye-dye interaction that leads to broadening the absorption profile, the contribution of aggregated state to the power conversion process is found out to be poor. Here we have engineered far red active π-extended cis-configured unsymmetrical squaraine dyes with carboxylic acid and cycnoacetic acid as anchoring groups with controlled aggregation and panchromatic light absorption by including the steric and electronic factors. The presence of sp3-C (out of plane) and N-alkyl (in plane) groups played an important role in modulating the assembly the dyes on the TiO2 electrode, cis-squaraine unit helps to extend the conjugation in the NIR region besides enhancing the visible transition and the incident photon-to-current conversion efficiency (IPCE) profile showed the importance of anchoring groups for the panchromatic response. Dye PSQ10 showed solar-to-electric conversion with an onset of 850 nm with the device performance of 7.0% (Voc = 0.581 V, Jsc = 17.06 mA/cm2, FF = 70 %).
关键词： cis-Squaraine dyes,panchromatic response,dye-sensitized solar cells,extended far-red absorption,dye aggregation
更新于2025-09-12 10:27:22
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Triphenylethylene- and Tetraphenylethylene-Functionalized 1,3-Bis(pyrrol-2-yl)squaraine Dyes: Synthesis, Aggregation-Caused Quenching to Aggregation-Induced Emission, and Thiol Detection
摘要： Three novel pairs of 1,3-bis(pyrrol-2-yl)squaraine dyes, N-alkylated SQ1a?1b, and N-phenylated SQ2a?2b in which triphenylethylene moieties functionalized at 5-position of pyrrole, as well as SQ3a?3b with tetraphenylethylene (TPE) moieties attached at N-position of pyrrole, were synthesized. All six dyes were found not to exhibit aggregation-induced emission (AIE) properties. Spectrophotometric studies showed that N-TPE-functionalized SQ3a?3b exhibited much larger molar extinction coefficients (ε: 1.36?2.14 × 105 M?1 cm?1) than 5,5′-triphenylethylene-functionalized SQ1a?2b (ε: 2.17?8.22 × 104 M?1 cm?1). Surprisingly, SQ2b showed a remarkable red-shifted maximum absorption (λmax: 723 vs 631?652 nm) compared to that of other squaraine dyes. All six squaraine dyes selectively responded to the addition of thiol-containing biomolecules, such as cysteine and gluthatione, with the disappearance of λmax in the near-infrared region in their respective absorption spectra. Interestingly, the thiolated species of SQ3a?3b were AIE active, with the characteristic AIE emission of TPE at λmax = 484?490 nm upon addition of water. Further thiol sensing on solid supports was examined, indicating the potential applications of TPE-functionalized squaraine dyes as bioprobes for the detection of important thiol-containing biomolecules, with a clear change from aggregation-caused quenching to AIE.
关键词： bioprobes,aggregation-induced emission,near-infrared,thiol detection,squaraine dyes
更新于2025-09-09 09:28:46
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Media Dependent Switching of Selectivity and Continuous Near Infrared Turn-on Fluorescence Response through Cascade Interactions from Noncovalent to Covalent Binding for Detection of Serum Albumin in Living Cells
摘要： Abnormal level of proteins is proved to be associated with diseases. Thus, protein sensing is helpful for clinical diagnosis and therapy. However, there is a great variety of protein species and relatively low concentration of each protein in complicated biological systems including other non-protein biomolecules. Therefore, it remains challenging to develop an effective method for detecting protein with high selectivity and sensitivity. Herein, a new self-assembly method based on a robust dye SQSS of which two squaraine molecules were conjugated through disulfide bond was developed for highly selective and sensitive detection of serum albumin (SA) in aqueous solution and live cells. SQSS can self-assemble into “compact” aggregates, offering “inert” disulfide group and very low background fluorescence through the combination of aggregation quenching and homogeneous fluorescence resonance energy transfer (homoFRET) quenching. The response of SQSS to SA undergoes two cascade stages. At the first stage, SA drives the compact assemblies of SQSS to form loose ones with fast speed (30 s) through noncovalent interaction, resulting in the enhancement of fluorescence to some extent. In this loose assembly state, the disulfide bond in SQSS is reactive. At the second stage, the Cys34 in SA slowly induced further disassembly through covalent binding with reactive disulfide bond, resulting in fluorescence further increasing and SQSS labeling to SA that cannot be displaced by site binding ligands of SA. The self-assemblies of SQSS can selectively detect SA with continuous near infrared (NIR) turn-on fluorescence response in 100% aqueous buffer solution. In addition, SQSS showed the potential application of imaging SA in living cells. On the other hand, the loose assembly state of SQSS was also achieved in aqueous solution with 20% CH3CN. In this media, thiol-containing glutathione (GSH) caused the disassembly of SQSS with turn-on fluorescence response through interaction with disulfide bond. SQSS can selectively recognize GSH over other amino acids even in the presence of other sulfhydryl amino acids. As a proof-of-concept method, the molecular self-assembly through multi-steps interactions would provide an ideal strategy for detection and live-cell imaging of bio-related molecules with high selectivity and signal-to-noise ratio.
关键词： squaraine dyes,disulfide linkage,glutathione,live-cell imaging,serum albumin,self-assemblies,noncovalent and covalent interactions
更新于2025-09-09 09:28:46