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Osmium sensitizer with enhanced spin-orbit coupling for panchromatic dye-sensitized solar cells
摘要： Low-lying triplet metal-to-ligand charge transfer (3MLCT) transitions of osmium complexes induced by spin-orbit coupling (SOC) is promising to extend photocurrent response when applied to dye-sensitized solar cells. In this study, we present a newly designed osmium complex (coded CYC-33O), incorporating a 2-thiohexyl-3,4-ethylenedioxythiophene functionalized bipyridyl ancillary ligand to red-shift the absorption and enhance the absorbance of both singlet and triplet MLCT transitions. Time-dependent density functional theory (TDDFT) calculations clearly signify the reinforced 1MLCT and 3MLCT transitions of CYC-33O mainly originate from osmium to 4,4',4"-tricarboxy-2,2':6',2"-terpyridine anchoring ligand, advantaging the heterogeneous electron transfer between CYC-33O and TiO2. The device sensitized with CYC-33O exhibits the panchromatic conversion beyond 1000 nm, yielding the photocurrent density of 19.38 mA cm–2 which is much higher than those of the cells based on the ruthenium analogue (CYC-33R) and model osmium complex (Os-3) sensitizers.
关键词： dye-sensitized solar cell,triplet metal-to-ligand charge transfer (3MLCT),ruthenium complex,spin-orbit coupling (SOC),osmium complex,time-dependent density functional theory (TDDFT)
更新于2025-09-23 15:21:01
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Effect of fluoro-substituted acceptor-based ancillary ligands on the photocurrent and photovoltage in dye-sensitized solar cells
摘要： Herein, we report four novel heteroleptic ruthenium (II) complexes, namely SD-7 to SD-10, containing fluoro- and trifluoro- methyl antennas as substituents on the ancillary ligands for dye-sensitized solar cells, and were compared to the benchmark dye N719. Photosensitizers (dyes) SD-7 to SD-10 were synthesized according to a typical one-pot three-step procedure with the corresponding ancillary ligands (LS-7 to LS-10). All the dyes were characterized by ATR-FTIR, 1H NMR and mass spectrometry. Furthermore, the photophysical, electrochemical and photovoltaic performances were compared with N719. The band gaps, ground and excited state oxidation potentials were measured. The photovoltaic performance of the dyes showed that SD-7 with five fluorine atoms and SD-8 with eCF3 at the –ortho position of the phenyl moiety outperformed the benchmark dye N719 with the efficiencies of 8.03% and 8.17%, respectively, with current density of 19.57 and 19.46 mA?cm?2, respectively, and open-circuit voltages of 0.65 V and 0.69 V, respectively, under optimized conditions. The fabricated solar devices at lab-scale showed a systematic trend of decreasing JSC when the fluoro-substituted dyes were sensitized on TiO2: SD-7 (with five –F) > SD-8 (with one eCF3 at ortho position) > SD-9 (with one eCF3 at para position) > SD-10 (with two eCF3, one at ortho and one at para position). This can be attributed to the greater number of fluorine atoms directly attached to sp2 hybridized carbon atoms, which greatly enhanced the dipole moment and intimate electronic coupling of SD-7 with TiO2 nanoparticles leading to better photocurrent density.
关键词： Fluoro-based dyes,Acceptor-based ancillary ligand,Photovoltaic performance,Dye-sensitized solar cells,Ruthenium complex
更新于2025-09-19 17:13:59
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Photophysical, electrochemical, and DFT studies of the novel azacrown-bridged dinuclear ruthenium dye sensitizers for solar cells
摘要： A dinuclear ruthenium bipyridyl complex with 1,10-diaza-18-crown-6 bridging ligand was synthesized and characterized. Its photophysical and electrochemical properties were also studied. DFT computations were performed to complement the experimental investigations. Analysis of the results indicates that the path in which charges move from one metal center to the other is significant for effective electronic coupling. However, electron transfer between the two ruthenium centers is hindered by the azacrown bridging ligand, compared to the smooth electronic transfer reported for a related dye involving an azo bridging ligand.
关键词： Bridging ligands,Dinuclear ruthenium complex,DFT,Charge transfer,Electronic coupling
更新于2025-09-12 10:27:22
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Role of phosphate in ruthenium-complex-sensitized TiO2 system for hydrogen production: mechanism and kinetics
摘要： Most Ru(II) complex-sensitized TiO2 systems for hydrogen (H2) production suffer from instability of the photosensitized system because the anchoring groups of Ru(II) dyes, which are required for their adsorption on TiO2, are intrinsically vulnerable to chemical and photochemical cleavage. In this study, a new method that enables the use of a Ru(II) dye without any anchoring groups (Ru(bpy)3 2+) was developed and investigated. The stable photocatalytic efficiency in repeated H2 production cycles under visible-light irradiation indicates that the Ru(II) dye without anchoring groups is highly stable during dye-sensitized H2 production. The dye-sensitized H2 production in the Ru(bpy)3 2+-sensitized TiO2 system comprising Ru(bpy)3 2+ as a photosensitizer, platinized TiO2 (Pt-TiO2) as a cocatalyst-electron mediator, and ethylenediaminetetraacetic acid as an electron donor was negligible. However, the addition of phosphate (PO4 3–) to the Ru(bpy)3 2+-sensitized TiO2 system enabled the production of H2 via dye sensitization in the absence of any anchoring groups on the dye. The adsorption of PO4 3– changed the surface charge of Pt-TiO2 from positive to negative under acidic conditions, thereby inducing adsorption of cationic Ru(bpy)3 2+ on the surface of Pt-TiO2 and facilitating electron transfer from excited Ru(bpy)3 2+ to the conduction band of TiO2. The PO4 3– adsorption-induced change in the surface charge and the subsequent adsorption of Ru(bpy)3 2+ on the surface of PO4 3–-adsorbed Pt-TiO2 were confirmed by zeta potential measurements and Fourier transform infrared spectroscopy, respectively. In contrast with H2 production, the presence of PO4 3– had little effect on the kinetics of anionic chromate (CrO4 2–) reduction in the Ru(bpy)3 2+-sensitized TiO2 system. This result indicates that electron transfer from Pt to the electron acceptor on PO4 3–-adsorbed Pt-TiO2 is highly dependent on the charge character of the electron acceptor (i.e., electron transfer to the cationic electron acceptor is more favored). The negative charge on the surface of Pt-TiO2 induced by the adsorption of PO4 3– attracts the positively charged protons to the surface, which kinetically enhanced electron transfer from Pt to the protons. The (photo)electrochemical data demonstrate that PO4 3– adsorbed on Pt-TiO2 facilitates the interfacial electron transfer processes by enhancing the adsorption of Ru(bpy)3 2+ and attracting protons to the surface. The positive effect of PO4 3– on H2 production increased with increasing PO4 3– concentration and decreasing pH, where the conditions are more favorable for PO4 3– and proton adsorption on the surface of Pt-TiO2. Among the five anions evaluated in this study (PO4 3–, AsO4 3–, F–, NO3 –, and SO4 2–), PO4 3– was most efficient and facilitated stable H2 production.
关键词： Phosphate,Dye sensitization,Hydrogen production,Photocatalysis,Ruthenium-complex
更新于2025-09-10 09:29:36
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Development of a nanoscale-based optical chemical sensor for the detection of NO radical
摘要： Nitric oxide is one of the most important biochemical parameters in biological processes; it is also known as carcinogenic. There is need for the design of stable and durable solid phase nitric oxide sensors. In this study, we immobilized the nitric oxide sensitive molecules pyrene, tris(2,2’-bipyrdyl)dichlororuthenium(II) hexahydrate (Ru(bipy) 2+ 3 ) , and magnesium phthalocyanine (Mg-Pc) for the first time in polymeric or glassy matrices. We applied silver nanoparticles and ionic liquids in the fabrication process of polymeric electrospun fibers and thin films. We compared their NO sensitivity in micelle solutions that mimic the cell medium by both steady state and lifetime-based fluorescence measurements. Among the tested dyes, the pyrene exhibited the highest response for radicalic NO. The Mg-Pc dye followed pyrene in terms of sensitivity and exhibited increasing fluorescence intensity and lifetime-based response. Lifetime-based response is advantageous and selective as it is not affected by source variations, photo-bleaching, or leaching effects. Another advantage of Mg-Pc dye is that it is not poisonous for organic systems. Presence of the ionic liquid enhanced the sensor response in all of the test moieties. The obtained limit of detection values for pyrene, Ru(bipy) 2+ and Mg-Pc dyes were 0.15 (cid:22) M, 1.54 (cid:22) M, and 0.78 (cid:22) M, respectively.
关键词： electrospinning,Nitric oxide radical,nanomaterials,ruthenium complex,magnesium phthalocyanine,pyrene,time resolved fluorescence
更新于2025-09-04 15:30:14