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Dannenhoffer AJ, Sai H, Harutyunyan B, Narayanan A, Powers-Riggs NE, Edelbrock AN, Passarelli JV, Weigand SJ, Wasielewski MR, Bedzyk MJ, Palmer LC, Stupp SI. Growth of Extra-Large Chromophore Supramolecular Polymers for Enhanced Hydrogen Production. Nano Lett 2021; 21:3745-3752. [PMID: 33877843 DOI: 10.1021/acs.nanolett.0c05024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The control of morphology in bioinspired chromophore assemblies is key to the rational design of functional materials for light harvesting. We investigate here morphological changes in perylene monoimide chromophore assemblies during thermal annealing in aqueous environments of high ionic strength to screen electrostatic repulsion. We found that annealing under these conditions leads to the growth of extra-large ribbon-shaped crystalline supramolecular polymers of widths from about 100 nm to several micrometers and lengths from 1 to 10 μm while still maintaining a unimolecular thickness. This growth process was monitored by variable-temperature absorbance spectroscopy, synchrotron X-ray scattering, and confocal microscopy. The extra-large single-crystal-like supramolecular polymers are highly porogenic, thus creating loosely packed hydrogel scaffolds that showed greatly enhanced photocatalytic hydrogen production with turnover numbers as high as 13 500 over ∼110 h compared to 7500 when smaller polymers are used. Our results indicate great functional opportunities in thermally and pathway-controlled supramolecular polymerization.
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Affiliation(s)
- Adam J Dannenhoffer
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
| | - Hiroaki Sai
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Boris Harutyunyan
- Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Ashwin Narayanan
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
| | - Natalia E Powers-Riggs
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Alexandra N Edelbrock
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - James V Passarelli
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Steven J Weigand
- Dow-Northwestern-DuPont Collaborative Access Team Synchrotron Research Center, Northwestern University, 9700 South Cass Avenue, Argonne, Illinois 60439 United States
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
- Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Liam C Palmer
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Simpson Querrey Institute, Northwestern University, 303 East Superior Street, Chicago, Illinois 60611, United States
| | - Samuel I Stupp
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States
- Center for Bio-Inspired Energy Science, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Medicine, Northwestern University, 676 North Saint Clair, Chicago, Illinois 60611, United States
- Simpson Querrey Institute, Northwestern University, 303 East Superior Street, Chicago, Illinois 60611, United States
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Dannenhoffer A, Sai H, Huang D, Nagasing B, Harutyunyan B, Fairfield DJ, Aytun T, Chin SM, Bedzyk MJ, Olvera de la Cruz M, Stupp SI. Impact of charge switching stimuli on supramolecular perylene monoimide assemblies. Chem Sci 2019; 10:5779-5786. [PMID: 31293765 PMCID: PMC6568310 DOI: 10.1039/c8sc05595e] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 04/30/2019] [Indexed: 11/21/2022] Open
Abstract
The development of stimuli-responsive amphiphilic supramolecular nanostructures is an attractive target for systems based on light-absorbing chromophores that can function as photosensitizers in water. We report here on a water soluble supramolecular carboxylated perylene monoimide system in which charge can be switched significantly by a change in pH. This was accomplished by substituting the perylene core with an ionizable hydroxyl group. In acidic environments, crystalline supramolecular nanoribbons with dimensions on the order of 500 × 50 × 2 nm form readily, while in basic solution the additional electrostatic repulsion of the ionized hydroxyl reduces assemblies to very small dimensions on the order of only several nanometers. The HOMO/LUMO levels were also found to be sensitive to pH; in acidic media the HOMO/LUMO levels are -5.65 and -3.70 eV respectively versus vacuum, whereas is in basic conditions they are -4.90 and -3.33 eV, respectively. Utilizing the assemblies as photosensitizers in photocatalytic production of hydrogen with [Mo3S13]2- as a catalyst at a pH of 4, H2 was generated with a turnover number of 125 after 18 hours. Charge switching the assemblies at a pH of 9-10 and using an iron porphyrin catalyst, protons could again be reduced to hydrogen and CO2 was reduced to CO with a turnover number of 30. The system investigated offers an example of dynamic photosensitizing assemblies that can drive reactions in both acidic and basic media.
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Affiliation(s)
- Adam Dannenhoffer
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA
| | - Hiroaki Sai
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA.,Simpson Querrey Institute , Northwestern University , 303 E. Superior , Chicago , Illinois 60611 , USA
| | - Dongxu Huang
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA
| | - Benjamin Nagasing
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA .
| | - Boris Harutyunyan
- Department of Physics and Astronomy , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA
| | - Daniel J Fairfield
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA
| | - Taner Aytun
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA
| | - Stacey M Chin
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA .
| | - Michael J Bedzyk
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA.,Department of Physics and Astronomy , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA
| | - Monica Olvera de la Cruz
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA.,Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA .
| | - Samuel I Stupp
- Department of Materials Science and Engineering , 2220 Campus Drive , Evanston , IL 60208 , USA.,Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA . .,Department of Medicine , Northwestern University , 676 N St. Clair , Chicago , Illinois 60611 , USA.,Simpson Querrey Institute , Northwestern University , 303 E. Superior , Chicago , Illinois 60611 , USA.,Department of Biomedical Engineering , Northwestern University , 2145 Sheridan Road , Evanston , IL 60208 , USA
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3
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Kazantsev RV, Dannenhoffer A, Aytun T, Harutyunyan B, Fairfield DJ, Bedzyk MJ, Stupp SI. Molecular Control of Internal Crystallization and Photocatalytic Function in Supramolecular Nanostructures. Chem 2018; 4:1596-1608. [PMID: 30740552 DOI: 10.1016/j.chempr.2018.04.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Supramolecular light-absorbing nanostructures are useful building blocks for the design of next-generation artificial photosynthetic systems. Development of such systems requires a detailed understanding of how molecular packing influences the material's optoelectronic properties. We describe a series of crystalline supramolecular nanostructures in which the substituents on their monomeric units strongly affects morphology, ordering kinetics, and exciton behavior. By designing constitutionally-isomeric perylene monoimide (PMI) amphiphiles, the effect of side chain sterics on nanostructure crystallization was studied. Molecules with short amine linked alkyl-tails rapidly crystallize upon dissolution in water, while bulkier tails require the addition of salt to screen electrostatic repulsion and annealing to drive crystallization. A PMI monomer bearing a 3-pentylamine tail was found to possess a unique structure that results in strongly red-shifted absorbance, indicative of charge-transfer exciton formation. This particular supramolecular structure was found to have an enhanced ability to photosensitize a thiomolybdate, [(NH4)2Mo3S13], catalyst to generate hydrogen gas.
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Affiliation(s)
- Roman V Kazantsev
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.,Argonne Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, IL 60208, USA
| | - Adam Dannenhoffer
- Department of Materials Science and Engineering, Evanston, IL 60208, USA
| | - Taner Aytun
- Department of Materials Science and Engineering, Evanston, IL 60208, USA
| | - Boris Harutyunyan
- Argonne Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, IL 60208, USA.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Daniel J Fairfield
- Department of Materials Science and Engineering, Evanston, IL 60208, USA
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Evanston, IL 60208, USA.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Samuel I Stupp
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.,Argonne Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, IL 60208, USA.,Department of Materials Science and Engineering, Evanston, IL 60208, USA.,Department of Medicine, Northwestern University, Chicago, IL 60611, USA.,Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA.,Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.,Lead Contact
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4
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Kazantsev RV, Dannenhoffer AJ, Weingarten AS, Phelan BT, Harutyunyan B, Aytun T, Narayanan A, Fairfield DJ, Boekhoven J, Sai H, Senesi A, O'Dogherty PI, Palmer LC, Bedzyk MJ, Wasielewski MR, Stupp SI. Crystal-Phase Transitions and Photocatalysis in Supramolecular Scaffolds. J Am Chem Soc 2017; 139:6120-6127. [PMID: 28436654 PMCID: PMC5556754 DOI: 10.1021/jacs.6b13156] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
![]()
The
energy landscape of a supramolecular material can include different
molecular packing configurations that differ in stability and function.
We report here on a thermally driven crystalline order transition
in the landscape of supramolecular nanostructures formed by charged
chromophore amphiphiles in salt-containing aqueous solutions. An irreversible
transition was observed from a metastable to a stable crystal phase
within the nanostructures. In the stable crystalline phase, the molecules
end up organized in a short scroll morphology at high ionic strengths
and as long helical ribbons at lower salt content. This is interpreted
as the result of the competition between electrostatic repulsive forces
and attractive molecular interactions. Only the stable phase forms
charge-transfer excitons upon exposure to visible light as indicated
by absorbance and fluorescence features, second-order harmonic generation
microscopy, and femtosecond transient absorbance spectroscopy. Interestingly,
the supramolecular reconfiguration to the stable crystalline phase
nanostructures enhances photosensitization of a proton reduction catalyst
for hydrogen production.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Andrew Senesi
- X-ray Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
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5
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Soe CMM, Stoumpos CC, Harutyunyan B, Manley EF, Chen LX, Bedzyk MJ, Marks TJ, Kanatzidis MG. Room Temperature Phase Transition in Methylammonium Lead Iodide Perovskite Thin Films Induced by Hydrohalic Acid Additives. ChemSusChem 2016; 9:2656-2665. [PMID: 27628708 DOI: 10.1002/cssc.201600879] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 08/15/2016] [Indexed: 06/06/2023]
Abstract
Although reactive additives have been employed in perovskite solar cells to enhance film morphology and significantly increase device performance, little is known about the effect of these additives on perovskite structural and optical properties. Here we report a systematic study of how the properties of methylammonium lead iodide perovskite (CH3 NH3 PbI3 ) are influenced by hydrohalic acid additives (HX; X=I, Br, Cl) in the precursor solution. Detailed structural and optical spectroscopic analysis reveals that all three acids affect the optical properties and alter the unit cell lattice parameters. Depending on the identity and concentration of HX, optical bandgaps widen or compress: addition of HBr yields a wider bandgap, whereas HI compresses the gap at high concentrations; HCl, on the other hand, has no significant effect on the bandgap. These changes can be understood by correlating them with the types of defects present in polycrystalline perovskite thin films in combination with the structural strain induced in very small crystallites. The presence of extra halides from HX in the precursor solution enables filling of the lattice vacancies in the perovskite, thereby altering metal-halogen-metal bond connectivity and consequently cell volumes and optical bandgaps. Remarkably, a room temperature tetragonal→cubic phase transition is observed for CH3 NH3 PbI3 films treated with high HX concentrations. Further insights into this anomalous phase transformation are obtained from in situ variable-temperature X-ray diffraction in the 25-55 °C (298-328 K) range, revealing a monotonic fall in transition temperature with increasing precursor solution HX concentration.
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Affiliation(s)
- Chan Myae Myae Soe
- Department of Chemistry, Northwestern University, Evanston, IL, 60628, USA
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA
| | | | - Boris Harutyunyan
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA
- Departments of Physics and Astronomy and Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Eric F Manley
- Department of Chemistry, Northwestern University, Evanston, IL, 60628, USA
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL, 60439, USA
| | - Lin X Chen
- Department of Chemistry, Northwestern University, Evanston, IL, 60628, USA
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave., Lemont, IL, 60439, USA
| | - Michael J Bedzyk
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA
- Departments of Physics and Astronomy and Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Tobin J Marks
- Department of Chemistry, Northwestern University, Evanston, IL, 60628, USA.
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA.
| | - Mercouri G Kanatzidis
- Department of Chemistry, Northwestern University, Evanston, IL, 60628, USA.
- Argonne-Northwestern Solar Energy Research Center, Northwestern University, Evanston, Illinois, 60208, USA.
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6
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Tsai H, Nie W, Blancon JC, Stoumpos CC, Asadpour R, Harutyunyan B, Neukirch AJ, Verduzco R, Crochet JJ, Tretiak S, Pedesseau L, Even J, Alam MA, Gupta G, Lou J, Ajayan PM, Bedzyk MJ, Kanatzidis MG. High-efficiency two-dimensional Ruddlesden-Popper perovskite solar cells. Nature 2016; 536:312-6. [PMID: 27383783 DOI: 10.1038/nature18306] [Citation(s) in RCA: 1147] [Impact Index Per Article: 143.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 05/03/2016] [Indexed: 01/20/2023]
Abstract
Three-dimensional organic-inorganic perovskites have emerged as one of the most promising thin-film solar cell materials owing to their remarkable photophysical properties, which have led to power conversion efficiencies exceeding 20 per cent, with the prospect of further improvements towards the Shockley-Queisser limit for a single‐junction solar cell (33.5 per cent). Besides efficiency, another critical factor for photovoltaics and other optoelectronic applications is environmental stability and photostability under operating conditions. In contrast to their three-dimensional counterparts, Ruddlesden-Popper phases--layered two-dimensional perovskite films--have shown promising stability, but poor efficiency at only 4.73 per cent. This relatively poor efficiency is attributed to the inhibition of out-of-plane charge transport by the organic cations, which act like insulating spacing layers between the conducting inorganic slabs. Here we overcome this issue in layered perovskites by producing thin films of near-single-crystalline quality, in which the crystallographic planes of the inorganic perovskite component have a strongly preferential out-of-plane alignment with respect to the contacts in planar solar cells to facilitate efficient charge transport. We report a photovoltaic efficiency of 12.52 per cent with no hysteresis, and the devices exhibit greatly improved stability in comparison to their three-dimensional counterparts when subjected to light, humidity and heat stress tests. Unencapsulated two-dimensional perovskite devices retain over 60 per cent of their efficiency for over 2,250 hours under constant, standard (AM1.5G) illumination, and exhibit greater tolerance to 65 per cent relative humidity than do three-dimensional equivalents. When the devices are encapsulated, the layered devices do not show any degradation under constant AM1.5G illumination or humidity. We anticipate that these results will lead to the growth of single-crystalline, solution-processed, layered, hybrid, perovskite thin films, which are essential for high-performance opto-electronic devices with technologically relevant long-term stability.
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7
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Zhou N, Prabakaran K, Lee B, Chang SH, Harutyunyan B, Guo P, Butler MR, Timalsina A, Bedzyk MJ, Ratner MA, Vegiraju S, Yau S, Wu CG, Chang RPH, Facchetti A, Chen MC, Marks TJ. Metal-free tetrathienoacene sensitizers for high-performance dye-sensitized solar cells. J Am Chem Soc 2015; 137:4414-23. [PMID: 25768124 DOI: 10.1021/ja513254z] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A new series of metal-free organic chromophores (TPA-TTAR-A (1), TPA-T-TTAR-A (2), TPA-TTAR-T-A (3), and TPA-T-TTAR-T-A (4)) are synthesized for application in dye-sensitized solar cells (DSSC) based on a donor-π-bridge-acceptor (D-π-A) design. Here a simple triphenylamine (TPA) moiety serves as the electron donor, a cyanoacrylic acid as the electron acceptor and anchoring group, and a novel tetrathienoacene (TTA) as the π-bridge unit. Because of the extensively conjugated TTA π-bridge, these dyes exhibit high extinction coefficients (4.5-5.2 × 10(4) M(-1) cm(-1)). By strategically inserting a thiophene spacer on the donor or acceptor side of the molecules, the electronic structures of these TTA-based dyes can be readily tuned. Furthermore, addition of a thiophene spacer has a significant influence on the dye orientation and self-assembly modality on TiO2 surfaces. The insertion of a thiophene between the π-bridge and the cyanoacrylic acid anchoring group in TPA-TTAR-T-A (dye 3) promotes more vertical dye orientation and denser packing on TiO2 (molecular footprint = 79 Å(2)), thus enabling optimal dye loading. Using dye 3, a DSSC power conversion efficiency (PCE) of 10.1% with Voc = 0.833 V, Jsc = 16.5 mA/cm(2), and FF = 70.0% is achieved, among the highest reported to date for metal-free organic DSSC sensitizers using an I(-)/I3(-) redox shuttle. Photophysical measurements on dye-grafted TiO2 films reveal that the additional thiophene unit in dye 3 enhances the electron injection efficiency, in agreement with the high quantum efficiency.
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Affiliation(s)
- Nanjia Zhou
- †Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Kumaresan Prabakaran
- ‡Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, ROC.,∇Department of Chemistry, PSG College of Arts and Science, Coimbatore, India-641014
| | - Byunghong Lee
- †Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Sheng Hsiung Chang
- §Research Center for New Generation Photovoltaics, National Central University, Chung-Li, Taiwan 32054, ROC
| | - Boris Harutyunyan
- †Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Peijun Guo
- †Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Melanie R Butler
- ∥Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Amod Timalsina
- ∥Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael J Bedzyk
- †Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Mark A Ratner
- ∥Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Sureshraju Vegiraju
- ‡Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, ROC
| | - Shuehlin Yau
- ‡Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, ROC
| | - Chun-Guey Wu
- ‡Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, ROC.,§Research Center for New Generation Photovoltaics, National Central University, Chung-Li, Taiwan 32054, ROC
| | - Robert P H Chang
- †Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Antonio Facchetti
- ∥Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.,⊥Polyera Corporation, 8045 Lamon Avenue, Skokie, Illinois 60077, United States
| | - Ming-Chou Chen
- ‡Department of Chemistry, National Central University, Chung-Li, Taiwan 32054, ROC
| | - Tobin J Marks
- ∥Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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