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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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Theoretical study on nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole
摘要： The first-, second- and third-order nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole in gas phase employing sum-over-states (SOS) method have been calculated for the first time. The ground state molecular structure of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole was obtained by the geometrical optimizations based on the B3LYP/6-31+G(d) level. The energy of excited states and transition dipole moments between different excited states were obtained by using the time-dependent density functional theory (TDDFT) based on the CAM-B3LYP/Sadlej POL level. Charge transfer during electron excitation was analyzed based on hole and electron distributions. Our calculations showed that the N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole has good nonlinear optical properties and its nonlinear optical properties arise from charge-transfer excitation and local excitation but charge transfer plays the leading role.
关键词： N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole,the time-dependent density functional theory (TDDFT),charge transfer,sum-over-states (SOS) method,nonlinear optical properties
更新于2025-09-19 17:15:36
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Many-body States Description of Single-molecule Electroluminescence Driven by Scanning Tunneling Microscope
摘要： Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention owing to their scientific importance and potential applications. With recent progresses of experimental techniques, especially by the virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it becomes possible to investigate single-molecule properties at sub-nanometer spacial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission is yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body state representation of the molecule. The effects of intra-molecular Coulomb interaction on conductance and luminescence spectra are investigated using the nonequilibrium Hubbard Green's function technique combined with first-principles calculations. We compare simulation results with experimental data and find that the intra-molecular Coulomb interaction is crucial for reproducing recent experiments for a single phthalocyanine molecule. The developed theory provides a unified description of both electron-transport and optical properties of a single molecule in contact with metal electrodes driven out of equilibrium, and thereby it contributes to a microscopic understanding of optoelectronic conversion in single molecules on solid surfaces and in nanometer-scale junctions.
关键词： Single molecule luminescence,exciton formation,nonequilibrium Hubbard Green's function technique,time-dependent density functional theory (TDDFT),scanning tunneling microscope-induced light emission,Vibronic interaction
更新于2025-09-19 17:15:36