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Martinez M, Nolen MA, Pompetti NF, Richter LJ, Farberow CA, Johnson JC, Beard MC. Controlling Electronic Coupling of Acene Chromophores on Quantum Dot Surfaces through Variable-Concentration Ligand Exchange. ACS NANO 2023; 17:14916-14929. [PMID: 37494884 PMCID: PMC10416565 DOI: 10.1021/acsnano.3c03498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/18/2023] [Indexed: 07/28/2023]
Abstract
Controlling the binding of functional organic molecules on quantum dot (QD) surfaces and the resulting ligand/QD interfacial structure determines the resulting organic-inorganic hybrid behavior. In this study, we vary the binding of tetracenedicarboxylate ligands bound to PbS QDs cast in thin films by performing solid-state ligand exchange of as-produced bound oleate ligands. We employ comprehensive Fourier-transform infrared (FTIR) analysis coupled with ultraviolet-visible (UV-vis) spectrophotometric measurements, transient absorption, and Density Functional Theory (DFT) simulations to study the QD/ligand surface structure and resulting optoelectronic properties. We find that there are three primary QD/diacid structures, each with a distinct binding mode dictated by the QD-ligand and ligand-ligand intermolecular and steric interactions. They can be accessed nearly independently of one another via different input ligand concentrations. Low concentrations produce mixed oleate/tetracene ligand structures where the tetracene carboxylates tilt toward QD surfaces. Intermediate concentrations produce mixed oleate/tetracene ligand structures with ligand-ligand interactions through intramolecular hydrogen bonding with the ligands perpendicular to the QD surface and weaker QD/ligand electronic interactions. High concentrations result in full ligand exchange, and the ligands tilt toward the surface while the QD film compacts. When the tetracene ligands tilt or lie flat on the QD surface, the benzene ring π-system interacts strongly with the p-orbitals at the PbS surface and produces strong QD-ligand interactions evidenced through QD/ligand state mixing, with a coupling energy of ≈700 meV.
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Affiliation(s)
- Marissa
S. Martinez
- Chemistry
& Nanoscience Center, National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
| | - Michelle A. Nolen
- Department
of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Nicholas F. Pompetti
- Department
of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Lee J. Richter
- Materials
Science and Engineering Division, National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Carrie A. Farberow
- Catalytic
Carbon Transformation & Scale-Up Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Justin C. Johnson
- Chemistry
& Nanoscience Center, National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
| | - Matthew C. Beard
- Chemistry
& Nanoscience Center, National Renewable
Energy Laboratory, Golden, Colorado 80401, United States
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2
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Williams ML, Schlesinger I, Jacobberger RM, Wasielewski MR. Mechanism of Ultrafast Triplet Exciton Formation in Single Cocrystals of π-Stacked Electron Donors and Acceptors. J Am Chem Soc 2022; 144:18607-18618. [PMID: 36178390 DOI: 10.1021/jacs.2c08584] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ultrafast triplet formation in donor-acceptor (D-A) systems typically occurs by spin-orbit charge-transfer intersystem crossing (SOCT-ISC), which requires a significant orbital angular momentum change and is thus usually observed when the adjacent π systems of D and A are orthogonal; however, the results presented here show that subnanosecond triplet formation occurs in a series of D-A cocrystals that form one-dimensional cofacial π stacks. Using ultrafast transient absorption microscopy, photoexcitation of D-A single cocrystals, where D is coronene (Cor) or pyrene (Pyr) and A is N,N-bis(3'-pentyl)-perylene-3,4:9,10-bis(dicarboximide) (C5PDI) or naphthalene-1,4:5,8-tetracarboxydianhydride (NDA), results in formation of the charge transfer (CT) excitons Cor•+-C5PDI•-, Pyr•+-C5PDI•-, Cor•+-NDA•-, and Pyr•+-NDA•- in <300 fs, while triplet exciton formation occurs in τ = 125, 106, 484, and 958 ps, respectively. TDDFT calculations show that the SOCT-ISC rates correlate with charge delocalization in the CT exciton state. In addition, time-resolved EPR spectroscopy shows that Cor•+-C5PDI•- and Pyr•+-C5PDI•- recombine to form localized 3*C5PDI excitons with zero-field splittings of |D| = 1170 and 1250 MHz, respectively. In contrast, Cor•+-NDA•- and Pyr•+-NDA•- give triplet excitons in which |D| is only 1240 and 690 MHz, respectively, compared to that of NDA (2091 MHz), which is the lowest energy localized triplet exciton, indicating that the Cor-NDA and Pyr-NDA triplet excitons have significant CT character. These results show that charge delocalization in CT excitons impacts both ultrafast triplet formation as well as the CT character of the resultant triplet states.
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Affiliation(s)
- Malik L Williams
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Itai Schlesinger
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Robert M Jacobberger
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Michael R Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
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3
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Hua T, Huang ZS, Cai K, Wang L, Tang H, Meier H, Cao D. Phenothiazine dye featuring encapsulated insulated molecular wire as auxiliary donor for high photovoltage of dye-sensitized solar cells by suppression of aggregation. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.02.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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4
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Pyrene and its selected 1-substituted derivatives revisited: A combined spectroscopic and computational investigation. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.03.098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Abstract
The current investigation achieves photochemical upconversion in pure water using combinations of water soluble Ru(ii) metal-to-ligand charge transfer (MLCT) sensitizers in concert with 9-anthracenecarboxylate (AnCO2−) and 1-pyrenecarboxylate (PyCO2−).
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Affiliation(s)
- Karim A. El Roz
- Department of Chemistry
- North Carolina State University
- Raleigh
- USA
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6
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Peters AW, Li Z, Farha OK, Hupp JT. Toward Inexpensive Photocatalytic Hydrogen Evolution: A Nickel Sulfide Catalyst Supported on a High-Stability Metal-Organic Framework. ACS APPLIED MATERIALS & INTERFACES 2016; 8:20675-81. [PMID: 27487409 DOI: 10.1021/acsami.6b04729] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Few-atom clusters composed of nickel and sulfur have been successfully installed into the Zr(IV)-based metal-organic framework (MOF) NU-1000 via ALD-like chemistry (ALD = atomic layer deposition). X-ray photoelectron spectroscopy and Raman spectroscopy are used to determine that primarily Ni(2+) and S(2-) sites are deposited within the MOF. In a pH 7 buffered aqueous solution, the porous catalyst is able to produce H2 gas at a rate of 3.1 mmol g(-1) h(-1) upon UV irradiation, whereas no H2 is generated by irradiating bare NU-1000. Upon visible light irradiation, little H2 generation was observed; however, with the addition of an organic dye, rose bengal, NiS-AIM can catalyze the production of H2 at an enhanced rate of 4.8 mmol g(-1) h(-1). These results indicate that ALD in MOFs (AIM) can engender reactivity within high surface area supports for applications in the solar fuels field.
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Affiliation(s)
- Aaron W Peters
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Zhanyong Li
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Omar K Farha
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemistry, Faculty of Science, King Abdulaziz University , Jeddah 21589, Saudi Arabia
| | - Joseph T Hupp
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States
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7
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Kathiravan A, Panneerselvam M, Sundaravel K, Pavithra N, Srinivasan V, Anandan S, Jaccob M. Unravelling the effect of anchoring groups on the ground and excited state properties of pyrene using computational and spectroscopic methods. Phys Chem Chem Phys 2016; 18:13332-45. [PMID: 27121202 DOI: 10.1039/c6cp00571c] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Anchoring groups play an important role in dye sensitized solar cells (DSCs). In order to acquire a suitable anchoring group for DSCs, a deeper understanding of the effect of anchoring groups on the ground and excited state properties of the dye is significant. In this context, various anchoring group connected pyrene derivatives are successfully synthesized and well characterized by using (1)H, (13)C-NMR, FT-IR and EI-MS spectrometry. The anchoring groups employed are carboxylic acid, malonic acid, acrylic acid, malononitrile, cyanoacrylic acid, rhodanine and rhodanine-3-acetic acid. The optimized geometries, HOMO-LUMO energy gap, light harvesting efficiency (LHE) and electronic absorption spectra of these dyes are studied by using density functional theory (DFT) calculations. The results show that pyrene connected with anchoring groups with weak electron pulling strength (PC, PAC and PMC) has a larger HOMO-LUMO energy gap, whereas that connected with anchoring groups with strong electron pulling strength (PCC, PMN, PR and PRA) has a reduced HOMO-LUMO energy gap. These molecules with a reduced energy gap are primarily preferred for DSC applications. Moreover, P, PC, PAC and PMC molecules undergo π→π* transition, whereas PCC, PMN, PR and PRA molecules show significant charge transfer along with π→π* transition. UV-visible absorption spectral studies on these dyes reveal that connecting various anchoring groups with different electron pulling abilities enables the pyrene chromophore to absorb in the longer wavelength region. Notably, an efficient bathochromic shift is observed for PCC, PMN, PR and PRA molecules in both electronic absorption and fluorescence spectral measurements, which suggests that the excitation is delocalized throughout the entire π-system of the molecules. Both theoretical and spectral studies reveal that dyes with an ICT character (PCC, PMN, PR and PRA) are suitable for dye sensitized solar cell applications.
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Affiliation(s)
- Arunkumar Kathiravan
- National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai - 600 113, Tamil Nadu, India.
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8
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Early-Late Heterometallic Complexes of Gold and Zirconium: Photoluminescence and Reactivity. Chemistry 2016; 22:7115-26. [DOI: 10.1002/chem.201600476] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Indexed: 01/21/2023]
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9
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Kumar R, Sankar M, Sudhakar V, Krishnamoorthy K. Synthesis and characterization of simple cost-effective trans-A2BC porphyrins with various donor groups for dye-sensitized solar cells. NEW J CHEM 2016. [DOI: 10.1039/c5nj02610e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Zn(ii) porphyrin dyes have been synthesized in three steps and exhibited power conversion efficiencies of 2.1 to 4.2% which depend on the electron donating ability of the R group.
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Affiliation(s)
- Ravi Kumar
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Muniappan Sankar
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Vediappan Sudhakar
- Polymers and Advanced Materials Laboratory
- National Chemical Laboratory
- Pune-411008
- India
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10
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Espinoza EM, Xia B, Darabedian N, Larsen JM, Nuñez V, Bao D, Mac JT, Botero F, Wurch M, Zhou F, Vullev VI. Nitropyrene Photoprobes: Making Them, and What Are They Good for? European J Org Chem 2015. [DOI: 10.1002/ejoc.201501339] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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11
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Kundu S, Metre RK, Yadav R, Sen P, Chandrasekhar V. Multi-Pyrene Assemblies Supported on Stannoxane Frameworks: Synthesis, Structure and Photophysical Studies. Chem Asian J 2014; 9:1403-12. [DOI: 10.1002/asia.201400054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Indexed: 01/05/2023]
Affiliation(s)
- Subrata Kundu
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016 (India), Fax: (+91) 521-259-0007/7436
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12
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O’Hanlon DC, Cohen BW, Moravec DB, Dallinger RF, Hopkins MD. Electronic, Redox, and Photophysical Consequences of Metal-for-Carbon Substitution in Oligo-Phenylene-Ethynylenes. J Am Chem Soc 2014; 136:3127-36. [DOI: 10.1021/ja411354d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Daniel C. O’Hanlon
- Department
of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Brian W. Cohen
- Department
of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Davis B. Moravec
- Department
of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Richard F. Dallinger
- Department
of Chemistry, Wabash College, Crawfordsville, Indiana 47933, United States
| | - Michael D. Hopkins
- Department
of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
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13
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Zervaki GE, Papastamatakis E, Angaridis PA, Nikolaou V, Singh M, Kurchania R, Kitsopoulos TN, Sharma GD, Coutsolelos AG. A Propeller-Shaped, Triazine-Linked Porphyrin Triad as Efficient Sensitizer for Dye-Sensitized Solar Cells. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201301278] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Han H, Tsarevsky NV. Employing exchange reactions involving hypervalent iodine compounds for the direct synthesis of azide-containing linear and branched polymers. Chem Sci 2014. [DOI: 10.1039/c4sc02254h] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Azide-containing polymers were prepared by one-pot polymerizations initiated by azide radicals produced by ligand exchange reactions involving hypervalent iodine(iii) compounds.
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Affiliation(s)
- Hongzhang Han
- Department of Chemistry and Center for Drug Discovery, Design
- Delivery in Dedman College
- Southern Methodist University
- Dallas, USA
| | - Nicolay V. Tsarevsky
- Department of Chemistry and Center for Drug Discovery, Design
- Delivery in Dedman College
- Southern Methodist University
- Dallas, USA
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15
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Green K, Gauthier N, Sahnoune H, Argouarch G, Toupet L, Costuas K, Bondon A, Fabre B, Halet JF, Paul F. Synthesis and Characterization of Redox-Active Mononuclear Fe(κ2-dppe)(η5-C5Me5)-Terminated π-Conjugated Wires. Organometallics 2013. [DOI: 10.1021/om400515g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katy Green
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Nicolas Gauthier
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Hiba Sahnoune
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Gilles Argouarch
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Loic Toupet
- Institut de Physique de Rennes,
UMR 6251 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Karine Costuas
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Arnaud Bondon
- RMN-ILP, UMR 6026 CNRS, Université de Rennes 1, IFR 140, PRISM, CS 34317,
Campus de Villejean, 35043 Rennes Cedex, France
| | - Bruno Fabre
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Jean-François Halet
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Frédéric Paul
- Institut des Sciences Chimiques
de Rennes, UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
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16
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One-step synthesis and photoluminescence properties of polycarbazole spheres and Ag/polycarbazole core/shell composites. Eur Polym J 2013. [DOI: 10.1016/j.eurpolymj.2013.02.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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17
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Francois A, Díaz R, Ramírez A, Loeb B, Barrera M, Crivelli I. Evaluation of the potential effectiveness of ruthenium(II) complexes with 2,3-disubtituted pyrazino[2,3-f][1,10]phenanthroline anchors, R2ppl (R=CN, COOH, COOEt, OH) as sensitizers for solar cells. Polyhedron 2013. [DOI: 10.1016/j.poly.2012.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Abstract
Nature has chosen chlorophylls in plants as antennae to harvest light for the conversion of solar energy in complicated photosynthetic processes. Inspired by natural photosynthesis, scientists utilized artificial chlorophylls - the porphyrins - as efficient centres to harvest light for solar cells sensitized with a porphyrin (PSSC). After the first example appeared in 1993 of a porphyrin of type copper chlorophyll as a photosensitizer for PSSC that achieved a power conversion efficiency of 2.6%, no significant advance of PSSC was reported until 2005; beta-linked zinc porphyrins were then reported to show promising device performances with a benchmark efficiency of 7.1% reported in 2007. Meso-linked zinc porphyrin sensitizers in the first series with a push-pull framework appeared in 2009; the best cell performed comparably to that of a N3-based device, and a benchmark 11% was reported for a porphyrin sensitizer of this type in 2010. With a structural design involving long alkoxyl chains to envelop the porphyrin core to suppress the dye aggregation for a push-pull zinc porphyrin, the PSSC achieved a record 12.3% in 2011 with co-sensitization of an organic dye and a cobalt-based electrolyte. The best PSSC system exhibited a panchromatic feature for light harvesting covering the visible spectral region to 700 nm, giving opportunities to many other porphyrins, such as fused and dimeric porphyrins, with near-infrared absorption spectral features, together with the approach of molecular co-sensitization, to enhance the device performance of PSSC. According to this historical trend for the development of prospective porphyrin sensitizers used in PSSC, we review systematically the progress of porphyrins of varied kinds, and their derivatives, applied in PSSC with a focus on reports during 2007-2012 from the point of view of molecular design correlated with photovoltaic performance.
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Affiliation(s)
- Lu-Lin Li
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan
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19
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Niko Y, Hiroshige Y, Kawauchi S, Konishi GI. Fundamental photoluminescence properties of pyrene carbonyl compounds through absolute fluorescence quantum yield measurement and density functional theory. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.05.072] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Ottonelli M, Piccardo M, Duce D, Thea S, Dellepiane G. Tuning the photophysical properties of pyrene-based systems: a theoretical study. J Phys Chem A 2011; 116:611-30. [PMID: 22103241 DOI: 10.1021/jp2084764] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Recently new molecular systems based on the pyrene moiety were developed for photovoltaic applications. Here we present the results of a quantum chemical study focused on the effects induced by some different substituents on the electronic properties of pyrene, to obtain general hints for the molecular design of new pyrene-based systems. In particular, a series of electron-donating (hydroxy, amino, acetylamino) and electron-withdrawing (cyano, carbamoyl, formyl, ethynyl, ethenyl) groups were considered. Furthermore, in addition to the single pyrene molecule, two pyrene units linked by ethenylene, ethynylene, 2,5-thienylene, and ethynylene-p-phenylene containing chains of different lengths were taken into account. For all of the model structures presented, the ground state geometries have been optimized using the density functional approach, while the vertical transition energies were calculated using the time-dependent density functional theory. We will show that the tuning of the lowest electronic excitation energy (i.e., the HOMO-LUMO energy gap) as well as the localization of the spatial distributions of the frontier molecular orbitals (i.e., the nature of the electron-hole pair, generated by photon absorption) can be obtained through the analysis of the pyrene frontier molecular orbitals. This approach allows to evaluate the most suitable position of the substituents on the pyrene moiety giving rise to enhanced electronic effects also in function of their electronic nature. In this way, pyrene-structures with tailored electronic properties could be modeled. Our screening shows that promising candidates for photovoltaic applications could be molecular structures formed by two pyrene units joined/linked by a short conjugated bridge containing double or triple bonds (henceforth pyrene-linked dimers). As far as the single pyrene units are considered, the most significant reduction of the transition energy of the lowest optical electronic excitation is obtained with disubstituted pyrenes with push-pull character.
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Affiliation(s)
- Massimo Ottonelli
- INSTM and Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, I-16146 Genova, Italy
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21
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Park Y, Felipe MJ, Advincula RC. Facile patterning of hybrid CdSe nanoparticle films by photoinduced surface defects. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4363-4369. [PMID: 22026749 DOI: 10.1021/am201012d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The photopatterning of CdSe quantum dots (QDs) films is facilitated by preparing defect-rich QDs on selective sites on the film. A key step is UV irradiation in the presence of a polar solvent such as methanol in situ as a "developer" which readily dissolves trioctylphosphine oxide (TOPO) but not the QDs. This results in a dramatically reduced photopatterning time and irradiation intensity requirement. The optical property changes were examined by UV-vis and fluorescence spectroscopy. Furthermore, the photo-oxidized pattern of the CdSe QD film was readily observed by fluorescence microscopy. The chemical change due to attenuation of the P═O vibration of TOPO (due to its removal) could be detected by FT-IR imaging or FT-IR chemical mapping. Thus, the protocol is a simple yet effective way of patterning PL properties of QD films at much reduced exposure time compared to previously reported methods. It may find utility for a host of cell-based film assays and PL display device applications at various resolutions.
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Affiliation(s)
- Yushin Park
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA
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22
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Rajakumar P, Visalakshi K, Ganesan S, Maruthamuthu P, Suthanthiraraj SA. Synthesis and Dye-sensitized Solar Cell Application of Polyolefinic Aromatic Molecules with Pyrene as Surface Group. Aust J Chem 2011. [DOI: 10.1071/ch10434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Synthesis of polyolefinic aromatic molecules with pyrene as the surface group, and their role as an additive in the redox couple of dye-sensitized solar cells, is described. The studies yield a promising power conversion efficiency of 5.27% with a short circuit current density of 6.50 mA cm–2, an open circuit voltage of 0.60 V, and a fill factor of 0.54 under 40 mW cm–2 simulated air mass (A.M.) 1.5 illumination. Most importantly, the photocurrent responsivity increases with an increase in the number of pyrene units on the surface.
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23
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Li MC, Ho RM, Lee YD. Photo-induced excimer formation of pyrene-labeled polymers for optical recording. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm03543b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. So far ruthenium(II) bipyridyl complexes have proven to be the most efficient TiO2 sensitizers in dye-sensitized solar cells. However, the highest power conversion efficiency has been stagnated in recent years. More importantly, considering that ruthenium is rare and expensive, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. To fulfill the requirement, it is crucial to develop inexpensive novel dyes that exhibit high efficiencies in terms of light-harvesting, charge separation, and charge collection. Porphyrins are important classes of potential sensitizers for highly efficient dye-sensitized solar cells owing to their photostability and potentially high light-harvesting capabilities that would allow applications in thinner, low-cost dye-sensitized solar cells. However, typical porphyrins possess an intense Soret band at 400 nm and moderate Q bands at 600 nm, which does not match solar energy distribution on the earth. Therefore, the unmatched light-harvesting property relative to the ruthenium complexes has limited the cell performance of porphyrin-sensitized TiO2 cells. Elongation of the -conjugation and loss of symmetry in porphyrins cause broadening and red-shift of the absorption bands together with an increasing intensity of the Q bands relative to that of the Soret band. On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved remarkably by the enhanced light absorption. The efficiency of porphyrin-sensitized solar cells could be improved significantly if the dyes with larger red and near-infrared absorption could be developed.
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Qu Q, Geng H, Peng R, Cui Q, Gu X, Li F, Wang M. Chemically binding carboxylic acids onto TiO2 nanoparticles with adjustable coverage by solvothermal strategy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9539-9546. [PMID: 20345108 DOI: 10.1021/la100121n] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This paper presents a solvothermal strategy for chemical modification of TiO(2) nanoparticles with carboxylic acids. Solvothermal reaction between the TiO(2) nanoparticles and carboxylic acid molecules in an autoclave at 100 degrees C provides carboxylic acid-modified TiO(2) particles with a modification efficiency much higher than the conventional immersion method. TiO(2) nanoparticles were prepared by hydrolysis of titanium isopropoxide in nitric acid solution; the modified nanoparticles were characterized by powder X-ray diffraction pattern, scanning electron microscopy, absorption and Fourier transform infrared spectra, and thermogravimetric analysis. Results show that the binding form of the modifier molecules on TiO(2) surface is in a bidentate chelating mode, the crystalline phase composition and morphological structure of the preformed TiO(2) nanoparticles are not affected by the solvothermal reaction, and the surface coverage of the modifier molecules can be adjusted by the weight ratio of modifier/TiO(2) during feeding. It is evident that the reaction processes in the solvothermal strategy involve the formation of double hydrogen bondings between carboxylic acid molecule and TiO(2) at the same Ti site and the coordination at solvothermal temperature by dehydration from the hydrogen bondings. The solvothermal strategy for modifying TiO(2) nanoparticles is expected to find potential applications in many fields; for example, our results demonstrate that the photovoltaic performance of the TiO(2) nanoparticles can be improved by the solvothermal modification even with an insulating modifier and controlled by the modifier coverage.
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Affiliation(s)
- Qiyun Qu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, PR China
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Lee KE, Gomez MA, Elouatik S, Demopoulos GP. Further understanding of the adsorption mechanism of N719 sensitizer on anatase TiO2 films for DSSC applications using vibrational spectroscopy and confocal Raman imaging. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9575-83. [PMID: 20429522 DOI: 10.1021/la100137u] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Vibrational spectroscopic studies of N719 dye-adsorbed TiO(2) films have been carried out by using SERRS, ATR-FTIR, and confocal Raman imaging. The high wavenumber region (3000-4000 cm(-1)) of dye adsorbed TiO(2) is analyzed via Raman and IR spectroscopy to investigate the role of surface hydroxyl groups in the anchoring mode. As a complementary technique, confocal Raman imaging is employed to study the distribution features of key dye groups (COO-, bipyridine, and C=O) on the anatase surface. Sensitized TiO(2) films made from two different nanocrystalline anatase powders are investigated: a commercial one (Dyesol) and our synthetic variety produced through aqueous synthesis. It is proposed the binding of the N719 dye to TiO(2) to occur through two neighboring carboxylic acid/carboxylate groups via a combination of bidentate-bridging and H-bonding involving a donating group from the N719 (and/or Ti-OH) units and acceptor from the Ti-OH (and/or N719) groups. The Raman imaging distribution of COO(-)(sym) on TiO(2) was used to show the covalent bonding, while the distribution of C=O mode was applied to observe the electrostatically bonded groups.
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Affiliation(s)
- Kee Eun Lee
- Materials Engineering, McGill University, Montreal, Canada, H3A 2B2.
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Zhang Y, Galoppini E. Organic polyaromatic hydrocarbons as sensitizing model dyes for semiconductor nanoparticles. CHEMSUSCHEM 2010; 3:410-428. [PMID: 20135672 DOI: 10.1002/cssc.200900233] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The study of interfacial charge-transfer processes (sensitization) of a dye bound to large-bandgap nanostructured metal oxide semiconductors, including TiO(2), ZnO, and SnO(2), is continuing to attract interest in various areas of renewable energy, especially for the development of dye-sensitized solar cells (DSSCs). The scope of this Review is to describe how selected model sensitizers prepared from organic polyaromatic hydrocarbons have been used over the past 15 years to elucidate, through a variety of techniques, fundamental aspects of heterogeneous charge transfer at the surface of a semiconductor. This Review does not focus on the most recent or efficient dyes, but rather on how model dyes prepared from aromatic hydrocarbons have been used, over time, in key fundamental studies of heterogeneous charge transfer. In particular, we describe model chromophores prepared from anthracene, pyrene, perylene, and azulene. As the level of complexity of the model dye-bridge-anchor group compounds has increased, the understanding of some aspects of very complex charge transfer events has improved. The knowledge acquired from the study of the described model dyes is of importance not only for DSSC development but also to other fields of science for which electronic processes at the molecule/semiconductor interface are relevant.
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Affiliation(s)
- Yongyi Zhang
- Department of Chemistry, Rutgers, the State University of New Jersey, Newark, NJ 07102,USA
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Thyagarajan S, Galoppini E, Persson P, Giaimuccio JM, Meyer GJ. Large footprint pyrene chromophores anchored to planar and colloidal metal oxide thin films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9219-9226. [PMID: 19719222 DOI: 10.1021/la9007679] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Sensitization and binding of a large footprint pyrene chromophore to planar (sapphire) and colloidal metal oxide films (TiO2 and ZrO2) is investigated. The model compound combines a 1-pyrenyl-ethynylenephenylene unit with a new adamantane-tripodal linker that binds to the surface. The linker design, combining a large footprint (approximately 2 nm2) of the tripodal linker with the meta position of the COOH anchoring groups, was suggested from atomistic models, and it aims to provide improved spacing control. The pyrene chromophore unit provides a probe of sensitizer-sensitizer interactions through its propensity to form excimers, unless neighboring pyrene units are sufficiently spaced (>or=3.5 A). Absorption and fluorescence studies, and a comparison with a pyrene-rigid rod model compound, suggest that the new tripodal anchor group allows spacing control on planar surfaces. On colloidal films, the linker provides spacing control at low surface coverage but sensitizer-sensitizer interactions are still observed on colloidal films at high surface coverage. Implications for the functionalization of metal oxide films in hybrid molecule-metal oxide semiconductor material systems are discussed.
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Affiliation(s)
- Sujatha Thyagarajan
- Chemistry Department, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, USA
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Galievsky VA, Malinovskii VL, Stasheuski AS, Samain F, Zachariasse KA, Häner R, Chirvony VS. Photophysical characterization of oligopyrene modules for DNA-based nanosystems. Photochem Photobiol Sci 2009; 8:1448-54. [PMID: 19789815 DOI: 10.1039/b9pp00016j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photophysics of free pyrenedicarboxamide (Py-DCA) in solution as well as of single-stranded and double-stranded oligonucleotides (ss and ds ONs) containing 1-7 pyrene building blocks per strand were studied by steady-state and time-resolved fluorescence spectroscopy. It was found that the fluorescence quantum yield Phi(F) of free Py-DCA chromophore in solution is rather high (Phi(F) = 0.44). However, after incorporation of the chromophore into a ss ON the monomeric chromophore fluorescence is quenched more than 40-fold due to electron-transfer reactions with ON bases. An increase of the number n of neighboring pyrenes in an ON results in Phi(F) growth up to 0.25 at n = 6. Starting from n = 2, all fluorescence belongs mainly to excimer formed by pyrene chromophores. Sections composed of multiple pyrenes may be considered as robust functional entities that may serve as independent modules in DNA-based, functional nano-architectures.
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Affiliation(s)
- Victor A Galievsky
- B.I. Stepanov's Institute of Physics, National Academy of Sciences of Belarus, Nezavisimosti ave. 68, 220072, Minsk, Belarus
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31
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One-dimensional Zn(II) oligo(phenyleneethynylene)dicarboxylate coordination polymers: Synthesis, crystal structures, thermal and photoluminescent properties. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2009.04.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Pal SK, Sundström V, Galoppini E, Persson P. Calculations of interfacial interactions in pyrene-Ipa rod sensitized nanostructured TiO2. Dalton Trans 2009:10021-31. [DOI: 10.1039/b910880g] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Matsunaga Y, Takechi K, Akasaka T, Ramesh AR, James PV, Thomas KG, Kamat PV. Excited-State and Photoelectrochemical Behavior of Pyrene-Linked Phenyleneethynylene Oligomer. J Phys Chem B 2008; 112:14539-47. [DOI: 10.1021/jp805878c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yoichiro Matsunaga
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
| | - Kensuke Takechi
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
| | - Takeshi Akasaka
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
| | - A. R. Ramesh
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
| | - P. V. James
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
| | - K. George Thomas
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
| | - Prashant V. Kamat
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305-8577, Japan, and Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695 019, India
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Rochford J, Galoppini E. Zinc(II) tetraarylporphyrins anchored to TiO2, ZnO, and ZrO2 nanoparticle films through rigid-rod linkers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:5366-5374. [PMID: 18410135 DOI: 10.1021/la703845u] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A series of six Zn(II) tetraphenylporphyrins (ZnTPP), with a phenyl (P) or oligophenyleneethynylene (OPE = (PE) n ) rigid-rod bridge varying in length (9-30 A) and terminated with an isophthalic acid (Ipa) anchoring unit, were prepared as model dyes for the study of sensitization processes on metal oxide semiconductor nanoparticle surfaces (MO(n) = TiO(2), ZnO, and insulating ZrO(2)). The dyes were designed such that the electronic properties of the central porphyrin chromophore remained consistent throughout the series, with the rigid-rod anchoring unit allowing each porphyrin unit to be located at a fixed distance from the metal oxide nanoparticle surface. Electronic communication between the porphyrin and the rigid-rod unit was not desired. Rigid-rod porphyrins ZnTPP-Ipa, ZnTPP-P-Ipa, ZnTPP-PE-Ipa, ZnTPP-(PE)(2)-Ipa, ZnTPP-(PE)(3)-Ipa, and ZnTMP-Ipa (with mesityl substituents on the porphyrin ring) were synthesized using combinations of mixed aldehyde condensations and Pd-catalyzed cross-coupling reactions. Their properties, in solution and bound, were compared with that of Zn(II) 5,10,15,20-tetra(4-carboxyphenyl)porphyrin ( p-ZnTCPP) as the reference compound. Solution UV-vis and steady-state fluorescence spectra for all six rigid-rod-Ipa porphyrins were almost identical to each other and to that of p-ZnTCPP. Cyclic voltammetry and differential pulse voltammetry scans of the methyl ester derivatives of the six rigid-rod-Ipa porphyrins, recorded in dichloromethane/electrolyte, exhibited redox behavior typical of ZnTPP porphyrins, with the first oxidation in the range +0.99 to 1.09 V vs NHE. All six rigid-rod-Ipa porphyrins and p-ZnTCPP were bound to metal oxide (MO(n) = TiO(2), ZnO, and insulating ZrO(2)) nanoparticle films. The Fourier transform infrared attenuated total reflectance spectra of all compounds bound to MO n films showed a broad band at 1553-1560 cm(-1) assigned to the v(CO(2)(-)) asymmetric stretching mode. Splitting of the Soret band into two bands at 411 and 423 nm in the UV-vis spectra of the bound compounds, and broadening and convergence of both fluorescence emission bands in the fluorescence spectra of the porphyrins bound to insulating ZrO(2) were also observed. Such changes were less evident for ZnTMP-Ipa, which has mesityl substituents on the porphyrin ring to prevent aggregation. Steady-state fluorescence emission of rigid-rod-Ipa porphyrins bound to TiO(2) and ZnO through the longest bridges (>14 A) showed residual fluorescence emission, while fluorescence quenching was observed for the shortest compounds.
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Affiliation(s)
- Jonathan Rochford
- Chemistry Department, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, USA
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35
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Surface Modification and Functionalization of Metal and Metal Oxide Nanoparticles by Organic Ligands. MONATSHEFTE FUR CHEMIE 2008. [DOI: 10.1007/s00706-007-0775-2] [Citation(s) in RCA: 294] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Muthiah C, Taniguchi M, Kim HJ, Schmidt I, Kee HL, Holten D, Bocian DF, Lindsey JS. Synthesis and Photophysical Characterization of Porphyrin, Chlorin and Bacteriochlorin Molecules Bearing Tethers for Surface Attachment. Photochem Photobiol 2007; 83:1513-28. [DOI: 10.1111/j.1751-1097.2007.00195.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Thyagarajan S, Liu A, Famoyin OA, Lamberto M, Galoppini E. Tripodal pyrene chromophores for semiconductor sensitization: new footprint design. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.05.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Rochford J, Chu D, Hagfeldt A, Galoppini E. Tetrachelate Porphyrin Chromophores for Metal Oxide Semiconductor Sensitization: Effect of the Spacer Length and Anchoring Group Position. J Am Chem Soc 2007; 129:4655-65. [PMID: 17385856 DOI: 10.1021/ja068218u] [Citation(s) in RCA: 227] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Four Zn(II)-tetra(carboxyphenyl)porphyrins in solution and bound to metal oxide (TiO2, ZnO, and ZrO2) nanoparticle films were studied to determine the effect of the spacer length and anchoring group position (para or meta) on their binding geometry and photoelectrochemical and photophysical properties. The properties of three types of anchoring groups (COOH and COONHEt3) for four Zn(II)-porphyrins (Zn(II)-5,10,15,20-tetra(4-carboxyphenyl)porphyrin (p-ZnTCPP), Zn(II)-5,10,15,20-tetra(3-carboxyphenyl)porphyrin (m-ZnTCPP), Zn(II)-5,10,15,20-tetra(3-(4-carboxyphenyl)phenyl)porphyrin (m-ZnTCP2P), and Zn(II)-5,10,15,20-tetra(3-ethynyl(4-carboxyphenyl)phenyl)porphyrin (m-ZnTC(PEP)P)) were compared. In m-ZnTCPP, m-ZnTCP2P, and m-ZnTC(PEP)P the four anchoring groups are in the meta position on the meso-phenyl rings of the porphyrin macrocycle, thus favoring a planar binding mode to the metal oxide surfaces. The three meta-substituted porphyrin salts have rigid spacer units of increasing length (phenyl (P), biphenyl (P2), and diphenylethynyl (PEP)) between the porphyrin ring and the carboxy anchoring groups, thus raising the macrocycle from the metal oxide surface. All porphyrins studied here, when bound to TiO2 and ZnO, exhibited quenching of the fluorescence emission, consistent with electron injection into the conduction band of the semiconductor. Steady-state UV-vis and fluorescence studies of p-ZnTCPP on insulating ZrO2 showed evidence of aggregation and exciton coupling. This was not observed in any of the meta-substituted porphyrins. The photoelectrochemical properties (IPCE, Voc, and Isc) of the porphyrins bound to TiO2 films in solar cells have been measured and rationalized with respect to the sensitizer binding geometry and distance from the surface.
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Affiliation(s)
- Jonathan Rochford
- Chemistry Department, Rutgers University, 73 Warren Street, Newark, NJ 07102, USA
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