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Pastore M, Caramori S, Gros PC. Iron-Sensitized Solar Cells (FeSSCs). Acc Chem Res 2024. [PMID: 38302460 DOI: 10.1021/acs.accounts.3c00613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
ConspectusThe harvesting and conversion of solar energy have become a burning issue for our modern societies seeking to move away from the exploitation of fossil fuels. In this context, dye-sensitized solar cells (DSSCs) have proven to be trustworthy alternatives to silicon-based cells with advantages in terms of transparency and efficiency under low illumination conditions. These devices are highly dependent on the ability of the sensitizer that they contain to collect sunlight and transfer an electron to a semiconductor after excitation. Ruthenium and polypyridine complexes are benchmarks in this field as they exhibit ideal characteristics such as long-lasting metal-ligand charge transfer (MLCT) states and efficient separation between electrons and holes, limiting recombination at the dye-semiconductor interface. Despite all of these advantages, ruthenium is a noble metal, and the development of more sustainable energy devices based on earth-abundant metals is now a must. A quick glance at the periodic table reveals iron as a potential good candidate, since it belongs to the same group of ruthenium, which suggests similar electronic properties. However, striking photophysical differences exist between ruthenium(II) polypyridyl complexes and their Fe(II) analogues, the latter suffering from short-lived MLCT states resulting of their ultrafast relaxation into metal-centered (MC) states. Pyridyl-N-heterocyclic carbenes (pyridylNHC) brought a strong σ-donor character required to promote a higher ligand field splitting of the iron d orbitals. This induces destabilization of the MC states over the MLCT manifold and a consequent slowdown of the excited states deactivation providing iron(II) complexes with tens of picoseconds lifetimes, making them more promising for applications in DSSCs. This Account highlights our recent advances in the development and characterization of iron-sensitized solar cells (FeSSCs) with a focus on the design of efficient sensitizers going from homoleptic to heteroleptic complexes (bearing different anchoring groups) and the tuning of electrolyte composition. Our rational approach led to the best photocurrent and efficiency ever reported for an iron sensitized solar cell (2% PCE and 9 mA/cm2) using a cosensitization process. This work clearly evidences that the solar energy conversion based on iron complex sensitization is now an opened and fruitful route.
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Affiliation(s)
| | - Stefano Caramori
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara,Via L. Borsari 46, 44121, Ferrara, Italy
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Reddy-Marri A, Marchini E, Cabanes VD, Argazzi R, Pastore M, Caramori S, Gros PC. Panchromatic light harvesting and record power conversion efficiency for carboxylic/cyanoacrylic Fe( ii) NHC co-sensitized FeSSCs. Chem Sci 2023; 14:4288-4301. [PMID: 37123187 PMCID: PMC10132143 DOI: 10.1039/d2sc05971a] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 03/23/2023] [Indexed: 04/05/2023] Open
Abstract
The co-sensitization of TiO2 by using a combination of carboxylic and thienylcyanoacrylic (ThCA)–Fe(ii) pyridyl-NHC sensitizers produced a panchromatic absorption and the best photocurrent and efficiency ever reported for an FeSSC.
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Affiliation(s)
- Anil Reddy-Marri
- Department of Chemistry, North Carolina State University, 851 Main Campus Drive, Raleigh, North Carolina, 27695-8204, USA
| | - Edoardo Marchini
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
| | | | - Roberto Argazzi
- CNR-ISOF c/o Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
| | | | - Stefano Caramori
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
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Cole JM, Mayer UFJ. Characterizing Interfacial Structures of Dye-Sensitized Solar Cell Working Electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:871-890. [PMID: 35014533 PMCID: PMC11386434 DOI: 10.1021/acs.langmuir.1c02165] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this feature article, we discuss the fundamental use of materials-characterization methods that directly determine structural information on the dye···TiO2 interface in dye-sensitized solar cells (DSCs). This interface is usually buried within the DSC and submerged in solvent and electrolyte, which renders such metrological work nontrivial. We will show how ex-situ X-ray reflectometry (XRR), atomic-force microscopy (AFM), grazing-incidence X-ray scattering (GIXS), pair-distribution-function analysis of X-ray diffraction data (gaPDF), and in-situ neutron reflectometry (NR) can be used to deliver specific structural information on the dye···TiO2 interface regarding dye anchoring, dye aggregation, molecular dye orientation, intermolecular spacing between dye molecules, interactions between the dye molecules and the TiO2 surface, and interactions between the dye molecules and the electrolyte components and precursors. Some of these materials-characterization techniques have been developed specifically for this purpose. We will demonstrate how the direct acquisition of such information from materials-characterization experiments is crucial for assembling a holistic structural picture of this interface, which in turn can be used to develop DSC design guidelines. Moreover, we will show how these methodologies can be used in the experimental-validation process of "design-to-device" pipelines for big-data- and machine-learning-based materials discovery. We conclude with an outlook on further developments of this design-to-device approach as well as the materials characterization of more dye···TiO2 interfacial structures that involve known DSC dyes using the methods described herein. In addition, we propose to combine these formally disparate metrologies so that their complementary merits can be exploited simultaneously. New metrologies of this kind could serve as a "one-stop-shop" for the materials characterization of surfaces, interfaces, and bulk structures in DSCs and other devices with layered architectures.
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Affiliation(s)
- Jacqueline M Cole
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom
| | - Ulrich F J Mayer
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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Deng K, Cole JM, Cooper JFK, Webster JRP, Haynes R, Al Bahri OK, Steinke NJ, Guan S, Stan L, Zhan X, Zhu T, Nye DW, Stenning GBG. Electrolyte/Dye/TiO 2 Interfacial Structures of Dye-Sensitized Solar Cells Revealed by In Situ Neutron Reflectometry with Contrast Matching. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1970-1982. [PMID: 33492974 DOI: 10.1021/acs.langmuir.0c03508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The nature of an interfacial structure buried within a device assembly is often critical to its function. For example, the dye/TiO2 interfacial structure that comprises the working electrode of a dye-sensitized solar cell (DSC) governs its photovoltaic output. These structures have been determined outside of the DSC device, using ex situ characterization methods; yet, they really should be probed while held within a DSC since they are modulated by the device environment. Dye/TiO2 structures will be particularly influenced by a layer of electrolyte ions that lies above the dye self-assembly. We show that electrolyte/dye/TiO2 interfacial structures can be resolved using in situ neutron reflectometry with contrast matching. We find that electrolyte constituents ingress into the self-assembled monolayer of dye molecules that anchor onto TiO2. Some dye/TiO2 anchoring configurations are modulated by the formation of electrolyte/dye intermolecular interactions. These electrolyte-influencing structural changes will affect dye-regeneration and electron-injection DSC operational processes. This underpins the importance of this in situ structural determination of electrolyte/dye/TiO2 interfaces within representative DSC device environments.
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Affiliation(s)
- Ke Deng
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Jacqueline M Cole
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
- Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
| | - Joshaniel F K Cooper
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - John R P Webster
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Richard Haynes
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Othman K Al Bahri
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Nina-Juliane Steinke
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Shaoliang Guan
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0FA, United Kingdom
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, United Kingdom
| | - Liliana Stan
- Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
| | - Xiaozhi Zhan
- Dongguan Neutron Science Center, Dongguan 523000, China
| | - Tao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Daniel W Nye
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Gavin B G Stenning
- ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
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Cole JM. Enumerating Intramolecular Charge Transfer in Conjugated Organic Compounds. J Chem Inf Model 2020; 60:6095-6108. [PMID: 33073566 DOI: 10.1021/acs.jcim.0c00913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Charge transfer across conjugated organic molecules is the functional basis of many optoelectronic and semiconductor devices. The ability to design such molecules to suit a given device application is highly desirable; yet, realizing this prospect is impeded by the lack of an algorithm that quantifies the extent of intramolecular charge transfer (ICT) in absolute terms. In turn, an algorithm to describe ICT is held back by a poor definition of one of its key dependent terms: conjugation. Current equations assume that π-bonding operates solely across two bonds, even though conjugation extends beyond these limits, and such equations only yield relative measures of π-conjugation. This work presents a four-step algorithm that enumerates ICT on an absolute scale. The method is applied successfully to four types of optoelectronic materials; results demonstrate the need to reconsider certain fundamental chemical-bonding and ICT concepts for conjugated molecules. These findings have implications for all optoelectronic and semiconducting materials.
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Affiliation(s)
- Jacqueline M Cole
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.,ISIS Neutron and Muon Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX, United Kingdom.,Department of Chemical Engineering and Biotechnology, University of Cambridge , West Cambridge Site, Philippa Fawcett Drive, Cambridge, CB3 0AS, United Kingdom.,Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom
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Xu F, Testoff TT, Wang L, Zhou X. Cause, Regulation and Utilization of Dye Aggregation in Dye-Sensitized Solar Cells. Molecules 2020; 25:E4478. [PMID: 33003462 PMCID: PMC7582523 DOI: 10.3390/molecules25194478] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/23/2020] [Accepted: 09/25/2020] [Indexed: 11/16/2022] Open
Abstract
As an important member of third generation solar cell, dye-sensitized solar cells (DSSCs) have the advantages of being low cost, having an easy fabrication process, utilizing rich raw materials and a high-power conversion efficiency (PCE), prompting nearly three decades as a research hotspot. Recently, increasing the photoelectric conversion efficiency of DSSCs has proven troublesome. Sensitizers, as the most important part, are no longer limited to molecular engineering, and the regulation of dye aggregation has become a widely held concern, especially in liquid DSSCs. This review first presents the operational mechanism of liquid and solid-state dye-sensitized solar cells, including the influencing factors of various parameters on device efficiency. Secondly, the mechanism of dye aggregation was explained by molecular exciton theory, and the influence of various factors on dye aggregation was summarized. We focused on a review of several methods for regulating dye aggregation in liquid and solid-state dye-sensitized solar cells, and the advantages and disadvantages of these methods were analyzed. In addition, the important application of quantum computational chemistry in the study of dye aggregation was introduced. Finally, an outlook was proposed that utilizing the advantages of dye aggregation by combining molecular engineering with dye aggregation regulation is a research direction to improve the performance of liquid DSSCs in the future. For solid-state dye-sensitized solar cells (ssDSSCs), the effects of solid electrolytes also need to be taken into account.
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Affiliation(s)
- Fang Xu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300345, China; (F.X.); (L.W.)
| | - Thomas T. Testoff
- Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901, USA;
| | - Lichang Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300345, China; (F.X.); (L.W.)
- Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901, USA;
| | - Xueqin Zhou
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300345, China; (F.X.); (L.W.)
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Sensitization of TiO2 by a symmetric anionic polymethine dye with three conjugated chromophores. RESEARCH ON CHEMICAL INTERMEDIATES 2019. [DOI: 10.1007/s11164-019-03889-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Paramasivam M, Chitumalla RK, Jang J, Youk JH. The impact of heteroatom substitution on cross-conjugation and its effect on the photovoltaic performance of DSSCs - a computational investigation of linear vs. cross-conjugated anchoring units. Phys Chem Chem Phys 2018; 20:22660-22673. [PMID: 30132478 DOI: 10.1039/c8cp02709a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The unusual bonding pattern and proximal heteroatom substitution in π-cross conjugation produced distinct changes in the energy levels and photophysical behaviour of the dyes. To seek an understanding of the origin of these fluctuations, we have carried out a detailed computational investigation on a series of D-π1-π2 (A1)-A2 structured dyes comprised of common donor-spacer (auxiliary acceptor) units but varied the anchoring parts. In this study, we introduced a novel dimethylamino substituted fluorene-based triarylamine donor unit and evaluated its donating strength. Based on the comparison of DFT computed energy levels with experimental results, we have proposed an orbital splitting pattern to explain the energy level and photophysical properties of the linear vs. cross-conjugated dyes with respect to the linking position of the anchoring unit and benzo[1,2,5]thiadiazole (BTD) substitution. The smallest HOMO-LUMO gap of B3 mainly originated from the weak overlap of the directionality mismatch of the orbital interaction imposed by cross-conjugation. The inefficient overlap in B3 can possibly influence the energy levels but failed to enhance the charge transfer transitions upon photoexcitation. On the other hand, β-heteroatom substitution in bridged dyes partially enhanced π-delocalization over the cross conjugation and produced a significant ICT absorption with an optoelectronic response in the NIR region. BTD acceptor substitution increased the HOMO-LUMO gap of the bridged dyes. NBO analysis was performed to corroborate our predictions. DOS-PDOS analysis of the dyes@TiO2 was employed to investigate the electron injection rate of linear vs. bridged dyes. The anchoring pattern and large torsional deviation of the carboxylate anchoring group upon TiO2 adsorption drastically decreased the photovoltaic performance of the bridged dyes. The results obtained from this study provided a detailed understanding of how to surmount the cross-conjugation with the aid of β-heteroatom substitution. These design guidelines would be helpful in developing novel NIR dyes with better hole mobility for various optoelectronic applications. Furthermore, π-delocalization over the cross-conjugation concept opens a new pathway in the field of functional molecular devices to increase the charge conductance over several orders of magnitude with a significant reduction of destructive quantum interference at the molecular junction.
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Cole JM. Data-Driven Molecular Engineering of Solar-Powered Windows. Comput Sci Eng 2018. [DOI: 10.1109/mcse.2018.011111129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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McCree-Grey J, Cole JM, Holt SA, Evans PJ, Gong Y. DyeTiO 2 interfacial structure of dye-sensitised solar cell working electrodes buried under a solution of I -/I 3- redox electrolyte. NANOSCALE 2017; 9:11793-11805. [PMID: 28786471 DOI: 10.1039/c7nr03936k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dye-sensitised solar cells (DSCs) have niche prospects for electricity-generating windows that could equip buildings for energy-sustainable future cities. However, this 'smart window' technology is being held back by a lack of understanding in how the dye interacts with its device environment at the molecular level. A better appreciation of the dyeTiO2 interfacial structure of the DSC working electrodes would be particularly valuable since associated structure-function relationships could be established; these rules would provide a 'toolkit' for the molecular engineering of more suitable DSC dyes via rational design. Previous materials characterisation efforts have been limited to determining this interfacial structure within an environment exposed to air or situated in a solvent medium. This study is the first to reveal the structure of this buried interface within the functional device environment, and represents the first application of in situ neutron reflectometry to DSC research. By incorporating the electrolyte into the structural model of this buried interface, we reveal how lithium cations from the electrolyte constituents influence the dyeTiO2 binding configuration of an organic sensitiser, MK-44, via Li+ complexation to the cyanoacrylate group. This dye is the molecular congener of the high-performance MK-2 DSC dye, whose hexa-alkyl chains appear to stabilise it from Li+ complexation. Our in situ neutron reflectometry findings are built up from auxiliary structural models derived from ex situ X-ray reflectometry and corroborated via density functional theory and UV/vis absorption spectroscopy. Significant differences between the in situ and ex situ dyeTiO2 interfacial structures are found, highlighting the need to characterise the molecular structure of DSC working electrodes while in a fully assembled device.
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Affiliation(s)
- Jonathan McCree-Grey
- Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, UK.
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