scholarly journals Two Excited State Collaboration of Heteroleptic Ir(III)-Coumarin Complexes for H2 Evolution Dye-Sensitized Photocatalysts

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2425
Author(s):  
Atsushi Kobayashi ◽  
Eiichirou Muramatsu ◽  
Masaki Yoshida ◽  
Masako Kato
Keyword(s):  
Tio2 Nanoparticles ◽  
Density Functional ◽  
Separation Efficiency ◽  
Monochromatic Light ◽  
Electron Injection ◽  
Methylphosphonic Acid ◽  
H2 Evolution ◽  
Semiconductor Interface ◽  
Visible Absorption ◽  
Dye Sensitized

Interfacial electron injection from a photoexcited surface-immobilized dye to a semiconductor substrate is a key reaction for dye-sensitized photocatalysts. We previously reported that the molecular orientation of heteroleptic Ir(III) photosensitizer on the TiO2 nanoparticle surface was important for efficient interfacial electron injection. In this work, to overcome the weak light absorption ability of heteroleptic Ir(III) photosensitizer and to improve the photoinduced charge-separation efficiency at the dye–semiconductor interface, we synthesized two heteroleptic Ir(III) complexes with different coumarin dyes, [Ir(C6)2(H4CPbpy)]Cl and [Ir(C30)2(H4CPbpy)]Cl [Ir-CX; X = 6 or 30; HC6 = 3-(2-enzothiazolyl)-7-(diethylamino)coumarin, HC30 = 3-(2-N-methylbenzimidazolyl)-7-N,N-diethylaminocoumarin, H4CPbpy = 4,4′-bis(methylphosphonic acid)-2,2′-bipyridine], as the cyclometalated ligands and immobilized them on the surface of Pt-cocatalyst-loaded TiO2 nanoparticles. Ultraviolet-visible absorption and emission spectroscopy revealed that the singlet ligand-centered (1LC) absorption and triplet 3LC emission bands of Ir-C30 occurred at shorter wavelengths than those of Ir-C6, while time-dependent density-functional-theory data suggested that the ligand-to-ligand charge transfer (LLCT) excited states of the two complexes were comparable. The photocatalytic H2 evolution activity of the Ir-C6-sensitized Pt-TiO2 nanoparticles (Ir-C6@Pt-TiO2) under visible light irradiation (λ > 420 nm) was higher than that of Ir-C30@Pt-TiO2. In contrast, their activities were comparable under irradiation with monochromatic light (λ = 450 ± 10 nm), which is absorbed comparably by both Ir-CX complexes. These results suggest that the internal conversion from the higher-lying LC state to the LLCT state effectively occurs in both Ir-CX complexes to trigger electron injection to TiO2.

Influence of Electron Injection Rate in Triphenylamine Based Dye for Dye-Sensitized Solar Cells: A First Principle Study

2019 ◽  
Vol 233 (9) ◽  
pp. 1247-1259
Author(s):  
Madhu Prakasam
Keyword(s):  
Solar Cells ◽  
Absorption Spectra ◽  
Density Functional ◽  
Dye Sensitized Solar Cells ◽  
Visible Region ◽  
Electron Injection ◽  
Injection Rate ◽  
Visible Absorption ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Abstract In this work, we systematically investigate the impacts of electron-donor based on Triphenylamine (TPA). The Geometry structure, energy levels, light-harvesting ability and ultraviolet-visible absorption spectra were calculated by using Density Functional Theory (DFT) and Time-Dependent-DFT. The electron injection rate of the TPA-N(CH3)2 based dyes has 0.71 eV for high among the dye sensitizer. The First and Second order Hyperpolarizability of the 11.95 × 10−30 e.s.u and 12195.54 a.u, respectively for TPA-N(CH3)2 based dye. The calculated absorption spectra were showed in the ultra-violet visible region for power conversion region. The study reveals that the electron transfer character of TPA-N(CH3)2 based dyes can be made suitable for applications in Dye-Sensitized Solar Cells.

Novel Ball-Type Dioxy-O-carborane Bridged Cobaltphthalocyanine: Synthesis, DFT Studies and Characterization for Dye-Sensitized Solar Cells as Photosensitizers

2018 ◽  
Author(s):  
Sevil ŞENER
Keyword(s):  
Solar Cells ◽  
Density Functional ◽  
Short Circuit ◽  
Photovoltaic Performance ◽  
Dye Sensitized Solar Cells ◽  
Performance Parameters ◽  
Visible Absorption ◽  
Dye Sensitized ◽  
Sensitization Time ◽  
Sensitized Solar Cells

The synthesis and spectroscopic characterization of an innovative ball-type cobalt (II)  metallophthalocyanine 4, bridged by four 1,2-bis(2-hydroxymethyl)-O-carborane (HMOC) 1 units has been achieved. The structure of 4 was characterized via elemental analysis, UV–visible absorption spectroscopy, FT-IR spectroscopy, and MALDI-TOF mass spectrometry. The photovoltaic performance of the newly synthesized compound in dye-sensitized solar cells was investigated. In order to clarify the effect of dye-sensitization time on photovoltaic performance parameters, the sensitization time was varied from 12 to 60 h and the performance parameters were investigated. It was found that sensitization time had a strong effect on the main performance parameters. The best photovoltaic performance was achieved after sensitization for 36 h (short circuit current density, 6.41 mA cm−2; overall conversion efficiency, 3.42%). Geometry optimization of the molecule was performed using density functional theory and shows a peripheral structure.

scholarly journals New 1,3,4-Oxadiazole Based Photosensitizers for Dye Sensitized Solar Cells (DSSCs)

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Umer Mehmood ◽  
Ibnelwaleed A. Hussein ◽  
Muhammad Daud
Keyword(s):  
Solar Cells ◽  
Density Functional ◽  
Electrochemical Impedance ◽  
Dye Sensitized Solar Cells ◽  
High Electron ◽  
Conjugation System ◽  
Native Form ◽  
Visible Absorption ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

1,3,4-Oxadiazole based photosensitizers with biphenyl, naphthalene, anthracene, and triphenylamine as the electron-donating moiety were synthesized for solar cell applications. In these photosensitizers, cyano groups were introduced as the electron acceptor and the anchor group because of their high electron-withdrawing ability and strong bonding to the semiconductor. Oxadiazole isomers were used as theπ-conjugation system, which bridges the donor-acceptor systems. The electrochemical and optical properties of the sensitizers were investigated both in their native form and upon incorporation into dye sensitized solar cells. The results of UV-visible absorption spectroscopy, electrochemical impedance spectroscopic measurements, and photocurrent voltage characteristics indicate that 1,3,4-oxadiazole pi-spacer with the anthracene moiety has the highest efficiency of 2.58%. Density functional theory was employed to optimize the structures of the sensitizers and the TiO2cluster.

scholarly journals Density Functional Theory Study on the Electronic Structures of Oxadiazole Based Dyes as Photosensitizer for Dye Sensitized Solar Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Umer Mehmood ◽  
Ibnelwaleed A. Hussein ◽  
Khalil Harrabi ◽  
Shakeel Ahmed
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Electron Injection ◽  
Molecular Structures ◽  
Visible Absorption ◽  
Functional Theory ◽  
Oxidation Potentials

The molecular structures and UV-visible absorption spectra of complex photosensitizers comprising oxadiazole isomers as theπ-bridges were analyzed by density functional theory (DFT) and time-dependent DFT. The ground state and excited state oxidation potentials, HOMOs and LUMOs energy levels, and electron injection from the dyes to semiconductor TiO2have been computed in vacuum here. The results show that all of the dyes may potentially be good photosensitizers in DSSC. To justify the simulation basis, N3 dye was also simulated under the similar conditions. Simulated absorption spectrum, HOMO, LUMO, and band gap values of N3 were compared with the experimental values. We also computed the electronic structure properties and absorption spectra of dye/(TiO2)8systems to elucidate the electron injection efficiency at the interface. This work is expected to give proper orientation for experimental synthesis.

scholarly journals Theoretical Study of theπ-Bridge Influence with Different Units of Thiophene and Thiazole in Coumarin Dye-Sensitized Solar Cells

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Rody Soto-Rojo ◽  
Jesús Baldenebro-López ◽  
Daniel Glossman-Mitnik
Keyword(s):  
Solar Cells ◽  
Molecular Orbital ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Dye Sensitized Solar Cells ◽  
Molecular Properties ◽  
Chemical Hardness ◽  
Visible Absorption ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Eight coumarin derivative dyes were studied by varying theπ-bridge size with different thiophene and thiazole units for their potential use in dye-sensitized solar cells (DSSC). Geometry optimization, the energy levels and electron density of the Highest Occupied Molecular Orbital and the Lowest Unoccupied Molecular Orbital, and ultraviolet-visible absorption spectra were calculated by Density Functional Theory (DFT) and Time-Dependent-DFT. All molecular properties were analyzed to decide which dye was the most efficient. Furthermore, chemical reactivity parameters, such as chemical hardness, electrophilicity index, and electroaccepting power, were obtained and analyzed, whose values predicted the properties of the dyes in addition to the rest of the studied molecular properties. Our calculations allow us to qualitatively study dye molecules and choose the best for use in a DSSC. The effects ofπ-bridges based on thiophenes, thiazoles, and combinations of the two were reviewed; dyes with three units mainly of thiazole were chosen as the best photosensitizers for DSSC.

2-Hexylthiophene-substituted Alizarin-based (D–π–A) Organic Dyes for Dye-sensitized Solar Cell Applications: Density Functional Theory and UV–Vis Studies

2020 ◽  
pp. 174751982092245
Author(s):  
Ismail Abubakari ◽  
Surendra Babu ◽  
Said Vuai ◽  
John Makangara
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Molecular Orbital ◽  
Density Functional ◽  
Dye Sensitized Solar Cells ◽  
Electron Injection ◽  
Basis Sets ◽  
Functional Theory ◽  
Oh Groups ◽  
Dye Sensitized

This work reports density functional theory and time-dependent density functional theory calculations of the optimized geometries, electronic structures and optical properties of molecular dyes D1, D2, D3, D4, D5, and D6 formulated through substitution of 2-hexylthiophene to alizarin using the hybrid functional B3LYP and 6-31G (d,p) basis sets. The dyes are considered as potential pigments for dye-sensitized solar cells. For all dyes, HOMO/LUMO (Highest Occupied Molecular Orbital/Lowest Unoccupied Molecular Orbital) analysis results in positive outcomes upon electron injection to semiconductors and subsequent dye regeneration by the electrolyte. It is found that charge transfer is from the thiophene and unsubstituted ring of alizarin to the substituted ring of alizarin containing C=O and OH groups. The C=O groups are observed to be very important in strengthening the dyes as they are revealed to be the anchoring group bonding to the TiO2 semiconductor. Comparatively, dye D6 is observed to possess high absorption ability and electron injection power through a study of the light-harvesting efficiency and injection driving force (Δ Ginject). The estimated values of open-circuit voltage ( Voc) for the computed dyes are also presented. Decisively, all the considered dyes prove to be useful as potential photosensitizers in solar cells using a TiO2 semiconductor and [Formula: see text] coupling electrolyte.

Theoretical Investigation of Anthocyanidin Aglycones as Photosensitizers for Dye-Sensitized TiO2 Solar Cells

2015 ◽  
Vol 1112 ◽  
pp. 317-320 ◽  
Author(s):  
Eka Cahya Prima ◽  
Brian Yuliarto ◽  
Suyatman ◽  
Hermawan Kresno Dipojono
Keyword(s):  
Solar Cells ◽  
Density Functional ◽  
Electron Injection ◽  
Dft Method ◽  
Open Circuit ◽  
Oxidation Potential ◽  
Functional Theory ◽  
Dye Sensitized ◽  
The Density Functional Theory ◽  
Dye Regeneration

The aim of this study is to analyze dye electronic properties of anthocyanin aglycones to be used as photosensitizers for TiO2solar cells. The dye properties will be examined by the density functional theory (DFT) method at IEF-PCM(UFF)/B3LYP/6-31+G(d,p) levels under ethanol and water environments. The results show that the position of LUMOs of all dyes lying over TiO2ECBwill facilitate good electron transfer while their HOMOs, which are lower than the electrolyte redox potential energy, can facilitate good oxidized-dye regeneration. Flavilium cation dye is the best anthocyanidin aglycone due to the best electron injection spontaneity of -0.807 eV as well as the highest open circuit voltage of 1.669 V. On the other hand, quinonoidal base dye gives the best light harvesting efficiency of 69.24% due to the best oscillating strength character. Moreover, the solvent effect is the important aspect regarding the dye oxidation potential stabilization as well as the electron injection driving force.

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