Singlet Fission in Carotenoid Aggregates (SIFICA)
Lead Research Organisation:
University of Sheffield
Department Name: Physics and Astronomy
Abstract
Singlet fission is the process whereby one photon creates two triplet excited states. If both triplet states could be harvested by a single-junction solar cell, the solar cell efficiency would increase by 1/3. There has been much academic and industrial interest in developing new materials for singlet fission, but to date no material has proved ideal.
Carotenoids are the most widespread of the natural pigments, important for photosynthesis, vision, human health and industry (market value $1.2bn). Surprisingly, carotenoids also appear to be excellent candidates for singlet fission sensitizers for solar cells: they have strong absorption, fast (<100fs) and loss-free singlet fission and they have the potential for energy-level tuning due the hundreds of naturally available molecules. However, problems remain: the triplet excitons are generally only short-lived in the solvent-based aggregates we have measured to date (90% decay in 1ns), making triplet harvesting difficult. A further problem is that a mechanism for triplet transfer to the solar cell has yet to be demonstrated. Here, we hope to solve these problems by using synthetic carotenoproteins designed to hold the carotenoid in a conformation which prevents triplet-triplet annihilation, allowing triplets to be long-lived. In addition, we propose to use the proteins to aid triplet harvesting through external spin-orbit coupling or energy transfer to a tethered nanoparticle.
We also propose to use these synthetic carotenoproteins as model systems to understand the fundamental energy landscape and dynamics in carotenoids and carotenoid dimers. Carotenoid dimers and aggregates are ubiquitous in nature, but their function is not yet understood. This is mainly due to the experimental and theoretical difficulty in studying them. Here we bring together experts in biochemistry, spectroscopy and theory to study model carotenoproteins with time-resolved spectrosopy and new theoretical models. This combination of resources and expertise provides us with the timely and exciting possibility of really understanding, controlling and exploiting carotenoid-based singlet fission for solar energy harvesting.
Carotenoids are the most widespread of the natural pigments, important for photosynthesis, vision, human health and industry (market value $1.2bn). Surprisingly, carotenoids also appear to be excellent candidates for singlet fission sensitizers for solar cells: they have strong absorption, fast (<100fs) and loss-free singlet fission and they have the potential for energy-level tuning due the hundreds of naturally available molecules. However, problems remain: the triplet excitons are generally only short-lived in the solvent-based aggregates we have measured to date (90% decay in 1ns), making triplet harvesting difficult. A further problem is that a mechanism for triplet transfer to the solar cell has yet to be demonstrated. Here, we hope to solve these problems by using synthetic carotenoproteins designed to hold the carotenoid in a conformation which prevents triplet-triplet annihilation, allowing triplets to be long-lived. In addition, we propose to use the proteins to aid triplet harvesting through external spin-orbit coupling or energy transfer to a tethered nanoparticle.
We also propose to use these synthetic carotenoproteins as model systems to understand the fundamental energy landscape and dynamics in carotenoids and carotenoid dimers. Carotenoid dimers and aggregates are ubiquitous in nature, but their function is not yet understood. This is mainly due to the experimental and theoretical difficulty in studying them. Here we bring together experts in biochemistry, spectroscopy and theory to study model carotenoproteins with time-resolved spectrosopy and new theoretical models. This combination of resources and expertise provides us with the timely and exciting possibility of really understanding, controlling and exploiting carotenoid-based singlet fission for solar energy harvesting.
Planned Impact
This is a 3-year project in a new field of interdisciplinary research. The short-term impacts are mainly enhancing the knowledge economy and training.
Scientific advances.
Despite their ubiquitousness and potential as singlet fission sensitizers, very little research has been done on the science of carotenoid dimers or aggregates. This project will begin to close the knowledge gap by creating new materials and applying new theoretical models. It could lead to a re-evaluation of the role of carotenoids in nature and as photonic materials. It may also open up new applications for non-natural proteins.
People.
The PDRAs employed on the grant will benefit from outstanding postdoctoral training: either from Sheffield's award-winning 'Think Ahead Programme' or Oxford's MPLS postdoc portal, from the opportunity to learn cutting-edge interdisciplinary experimental and theoretical techniques (e.g. synthetic biology, ultrafast spectroscopy, DMRG) and they will gain supervision skills by mentoring, training and helping the PhD students associated with this project.
This project will have an impact on the PI's career as it is her first large grant as PI. She will be supported by very experienced researchers (Prof. Hunter, Prof. Barford) and a lab manager who has 7 years' experience in managing large grants. As such, it is the ideal project to develop as a lead researcher.
Economy.
On the longer-term, it is difficult to predict impact. Should we be able to produce protein films which show efficient NIR emission from pairs of triplet excitons, we will collaborate with The University of Cambridge and Eight19 to develop and commercialise the technology. This commercialisation is likely to be important and will allow the UK to capitalise on its early lead in singlet fission research. It is also possible that other aspects of the research are picked up by companies either interested in water-soluble carotenoids or carotenoids with tunable electronic and optical properties (e.g. BASF, Boots, Nutrilite, Unilever, IBR) or any technological developments we make (Ossila).
Society.
In the long-term, any commercialisation or development of more efficient solar cells will benefit the global society by providing a clean energy source. Beyond a certain value, increases in solar cell efficiency can reduce cost making solar energy more affordable and competitive. Using biosynthetic, biodegradable carotenoids in cosmetics could help build the circular economy and boost the carotenoid market. In addition, as carotenoids are biosynthesised in algae and cyanobacteria (which can be used to clean harsh industrial wastewater), there is future scope for using these applications to add value to biofuel synthesis.
Scientific advances.
Despite their ubiquitousness and potential as singlet fission sensitizers, very little research has been done on the science of carotenoid dimers or aggregates. This project will begin to close the knowledge gap by creating new materials and applying new theoretical models. It could lead to a re-evaluation of the role of carotenoids in nature and as photonic materials. It may also open up new applications for non-natural proteins.
People.
The PDRAs employed on the grant will benefit from outstanding postdoctoral training: either from Sheffield's award-winning 'Think Ahead Programme' or Oxford's MPLS postdoc portal, from the opportunity to learn cutting-edge interdisciplinary experimental and theoretical techniques (e.g. synthetic biology, ultrafast spectroscopy, DMRG) and they will gain supervision skills by mentoring, training and helping the PhD students associated with this project.
This project will have an impact on the PI's career as it is her first large grant as PI. She will be supported by very experienced researchers (Prof. Hunter, Prof. Barford) and a lab manager who has 7 years' experience in managing large grants. As such, it is the ideal project to develop as a lead researcher.
Economy.
On the longer-term, it is difficult to predict impact. Should we be able to produce protein films which show efficient NIR emission from pairs of triplet excitons, we will collaborate with The University of Cambridge and Eight19 to develop and commercialise the technology. This commercialisation is likely to be important and will allow the UK to capitalise on its early lead in singlet fission research. It is also possible that other aspects of the research are picked up by companies either interested in water-soluble carotenoids or carotenoids with tunable electronic and optical properties (e.g. BASF, Boots, Nutrilite, Unilever, IBR) or any technological developments we make (Ossila).
Society.
In the long-term, any commercialisation or development of more efficient solar cells will benefit the global society by providing a clean energy source. Beyond a certain value, increases in solar cell efficiency can reduce cost making solar energy more affordable and competitive. Using biosynthetic, biodegradable carotenoids in cosmetics could help build the circular economy and boost the carotenoid market. In addition, as carotenoids are biosynthesised in algae and cyanobacteria (which can be used to clean harsh industrial wastewater), there is future scope for using these applications to add value to biofuel synthesis.
Publications



Bossanyi D
(2022)
In optimized rubrene-based nanoparticle blends for photon upconversion, singlet energy collection outcompetes triplet-pair separation, not singlet fission
in Journal of Materials Chemistry C


Bossanyi DG
(2021)
Emissive spin-0 triplet-pairs are a direct product of triplet-triplet annihilation in pentacene single crystals and anthradithiophene films.
in Nature chemistry


Gardiner AT
(2021)
The 2.4 Å cryo-EM structure of a heptameric light-harvesting 2 complex reveals two carotenoid energy transfer pathways.
in Science advances

Musser A
(2019)
Triplet-Pair States in Organic Semiconductors
in Annual Review of Physical Chemistry

Musser AJ
(2019)
Heavy-atom effects on intramolecular singlet fission in a conjugated polymer.
in The Journal of chemical physics

Niedzwiedzki DM
(2020)
A photosynthetic antenna complex foregoes unity carotenoid-to-bacteriochlorophyll energy transfer efficiency to ensure photoprotection.
in Proceedings of the National Academy of Sciences of the United States of America
Description | (1) We solved a 40-year puzzle in the literature, explaining how - and potentially why - singlet fission occurs in photosynthetic complexes. This work is currently under review. (2) We demonstrated synthetic carotenoid-protein complexes capable of singlet exciton fission, to our knowledge for the first time. (JACS 2020) (3) Using model carotenoid-protein systems, we showed that a twist along a carotenoid backbone is not sufficient to enable intramolecular singlet fission. (under review) (4) We demonstrated that the maximum efficiency of triplet-triplet annihilation, the reverse of singlet fission, is broadly under-estimated in the literature and showed how to design molecules to maximise the spin statistical efficiency to 100% using reverse intersystem crossing and cofacial packing. (JACS 2021) |
Exploitation Route | We expect the results to aid researchers in synthetic biology and singlet fission to understand how to make, use and characterise synthetic proteins and to understand the photophysics of singlet fission, triplet-triplet annihilation and potentially pigment complexes for quantum-based applications. We have demonstrated, for example, that internal conversion is always competitive with intermolecular singlet fission in carotenoid-based systems with long-lived triplets. |
Sectors | Agriculture Food and Drink Chemicals Energy |
Description | There have been two non-academic impacts from this work. Firstly, we have been contacted by a company specialising in medical imaging to measure biomarkers using our spectroscopic techniques. Secondly, and related only indirectly, the PI has been asked to present at active travel events. The skills acquired during this project (and other funded projects she has worked on) have directly enabled her to be able to present complex data in an engaging and easy-to-understand manner. This training has led her to being invited to two conferences (2022, 2023) outside her main area of expertise. Policy makers from Wales and England have been in touch, including local councillors and MPs to request the presentation and more information. This highlights the importance of interdisciplinary research and transferrable skills. |
First Year Of Impact | 2022 |
Sector | Manufacturing, including Industrial Biotechology,Transport |
Impact Types | Societal Policy & public services |
Description | Case studentship (EPSRC + Calico) |
Amount | £123,556 (GBP) |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2024 |
End | 09/2028 |
Description | Daniel Hook EPSRC Studentship |
Amount | £54,631 (GBP) |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2019 |
End | 09/2023 |
Description | IAA Funding for Calico 6 month postdoc |
Amount | £27,000 (GBP) |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 04/2023 |
End | 11/2023 |
Description | Molecular Photonic Breadboards |
Amount | £7,255,283 (GBP) |
Funding ID | EP/T012455/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 11/2020 |
End | 11/2026 |
Description | Reconnect Travel Grant |
Amount | £12,000 (GBP) |
Organisation | British Council |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 04/2023 |
End | 04/2024 |
Description | Rob Gordon Studentship |
Amount | £54,631 (GBP) |
Funding ID | 210152865 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 09/2021 |
End | 09/2025 |
Title | Data for "In optimized rubrene-based nanoparticle blends for photon upconversion, singlet energy collection outcompetes triplet-pair separation, not singlet fission" |
Description | The complete dataset underlying the article "In optimized rubrene-based nanoparticle blends for photon upconversion, singlet energy collection outcompetes triplet-pair separation, not singlet fission". Source data is provided here for figures in both the main article and supplementary information. See README.html for details. |
Type Of Material | Database/Collection of data |
Year Produced | 2021 |
Provided To Others? | Yes |
URL | https://figshare.shef.ac.uk/articles/dataset/Data_for_In_optimized_rubrene-based_nanoparticle_blends... |
Title | Data for "Spin statistics for triplet-triplet annihilation upconversion: exchange coupling, intermolecular orientation and reverse intersystem crossing" |
Description | The complete dataset underlying the article "Spin statistics for triplet-triplet annihilation upconversion: exchange coupling, intermolecular orientation and reverse intersystem crossing". Source data is provided here for figures in both the main article and supplementary information. See README.html for details. |
Type Of Material | Database/Collection of data |
Year Produced | 2021 |
Provided To Others? | Yes |
URL | https://figshare.shef.ac.uk/articles/dataset/Data_for_Spin_statistics_for_triplet-triplet_annihilati... |
Title | Data for 'Twisted Carotenoids Do Not Support Efficient Intramolecular Singlet Fission in the Orange Carotenoid Protein' |
Description | This dataset contains the data shown in the article 'Twisted Carotenoids Do Not Support Efficient Intramolecular Singlet Fission in the Orange Carotenoid Protein' (J. Phys. Chem. Lett., 2023, DOI: 10.1021/acs.jpclett.3c01139). The dataset is provided as a zip file ('Data.zip'). To access the contained data and folders, please download the zip file, and extract it using a file archiver program. Where possible, both raw and analysed data have been included, along with the finalised versions of the figures. Please refer to the README files for further details (including an index specifying the contents). We recommend opening 'README.html' in a web browser to view with HTML formatting, or if not available, opening 'README.md' within a text editor. |
Type Of Material | Database/Collection of data |
Year Produced | 2023 |
Provided To Others? | Yes |
URL | https://figshare.shef.ac.uk/articles/dataset/Data_for_Twisted_Carotenoids_Do_Not_Support_Efficient_I... |
Description | Calico partnership |
Organisation | Calico Life Sciences |
Country | United States |
Sector | Private |
PI Contribution | To measure triplet states of fluorescent proteins (KE studentship) and to understand and help design the magnetic-field dependent properties of FPs. |
Collaborator Contribution | To design and supply FPs and contribute to impact. |
Impact | None yet. |
Start Year | 2022 |
Description | Kyushu chemistry collaboration |
Organisation | Kyushu University |
Country | Japan |
Sector | Academic/University |
PI Contribution | During this EPSRC grant we developed new techniques, instruments and knowledge that directly resulted in this collaboration. We work with our Kyushu partners to understand the fundamental physics and physical chemistry of new up-conversion and organic quantum materials. We measure time-resolved and temperature- and magnetic-field dependent spectroscopy of new materials designed and synthesised in Kyushu. Our results and understanding lend themselves to their new molecular designs. |
Collaborator Contribution | The group in Kyushu led by Prof. Yanai design and synthesise new compounds for solar energy harvesting and quantum applications. They pass on their knowledge and materials to us and we measure them. They also send PhD students to Sheffield and together we have applied for one successful and one unsuccessful funding bid. (Not from UKRI). |
Impact | * J. Am. Chem. Soc. Au (2021) * J. Mater. Chem. C (2022) * unsuccessful funding bid * successful travel grant (British Council) |
Start Year | 2019 |
Description | Talks at active travel events |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Policymakers/politicians |
Results and Impact | Using transferrable skills learned directly by working and managing a physics lab and giving talks at international conferences means that, following applying for some funding, I have been invited to give talks at active travel events. Odd though this may sound, knowledge about the hierarchy of safety management from working with and managing labs and about how to present complex data in an engaging and easy-to-understand manner has meant that I have been able to present data on risk and travel in an engaging (and perhaps unusual way). I found that policy-makers, general public and professional practitioners reported changed attitues and that policies are starting to change on a local level (though slowly). |
Year(s) Of Engagement Activity | 2022,2023 |