Periodic Reporting for period 1 - FastTrack (Photons and Electrons on the Move)
Berichtszeitraum: 2022-11-01 bis 2025-04-30
How does nature dynamically re-organize the membrane architecture, its packing, order, diffusion, on light stress? Which pathways are taken to charge separation? What is the role of fluctuations, coherences, color and vibrations? Using our expertise in fs pulse control and nanoimaging, we aim to address photosynthetic light-to-charge transfer in real nanospace and ultrafast. Specific objectives:
Energy transport on the nanoscale: tracking spatiotemporal membrane transport by super-resolved transient optical microscopy and nanophotonic light localization: to reveal disorder and quantify diffusion.
Light to charge: photo-current detection of the energy flow: by ultrafast photo-thermoelectric graphene and photo-electrochemical detection I will probe charge separation of the reaction center directly, quantify rate and efficiency.
Multidimensional spectra on the nanoscale: by collinear 2D spectroscopic imaging with photocurrent and fluorescence detection, I will map the development of the energy landscape, at special membrane spots, ultimately on a single complex.
Functional imaging: visualize the dynamic light-response of the membrane architecture, the changes in packing density, (dis)order, diffusion and pathways to charge separation.
Energy transport on the nanoscale: tracking spatiotemporal membrane transport by super-resolved transient optical microscopy and nanophotonic light localization: to reveal disorder and quantify diffusion.
Light to charge: photo-current detection of the energy flow: by ultrafast photo-thermoelectric graphene and photo-electrochemical detection I will probe charge separation of the reaction center directly, quantify rate and efficiency.
Multidimensional spectra on the nanoscale: by collinear 2D spectroscopic imaging with photocurrent and fluorescence detection, I will map the development of the energy landscape, at special membrane spots, ultimately on a single complex.
Functional imaging: visualize the dynamic light-response of the membrane architecture, the changes in packing density, (dis)order, diffusion and pathways to charge separation.
We managed to show the very first tracking of excitons at conditions below sunlight; first as a proof of concept on photovoltaic materials, showing the full absence of non-linear annihilation; next a real application on a light-harvesting membrane. This achievement is crucial for any success in this project. Brinatti Vazquez et al., Structured Excitation Energy Transfer: Tracking Exciton Diffusion below Sunlight Intensity", ACS Photonics 11 (3), 1318-1326 (2024).
Using Photoelectrochemical Two-Dimensional Electronic Spectroscopy we recorded the first 2D spectra on plant Photosystem I, providing a 2D-map of the first ps, López-Ortiz et al., Photoelectrochemical Two-Dimensional Electronic Spectroscopy (PEC2DES) of Photosystem I: Charge Separation Dynamics Hidden in a Multichromophoric Landscape, ACS Appl. Mater. Interfaces, 16 (33), 43451 – 43461 (2024).
The photocurrent detected 2DES turned out to compensate terms in its nonlinear response, moreover multi-chromophoric ground state bleach dominated over stimulated emissions. We explained these unexpected contrast issues and proposed effected compressed sensing for effective data collection. Bolzonello et al., Nonlinear Optical Spectroscopy of Molecular Assemblies: What Is Gained and Lost in Action Detection?', J. Phys. Chem. Lett. 14 (50), 11438 – 11446 (2023); Bolzonello et al., Fisher information for smart sampling in time-domain spectroscopy, J. Chem. Phys., 160, 214110 (2024).
To pursue the photocurrent spectroscopy on 2D -material substrate, we engineered dual action spectroscopy, a photocurrent- and luminescence-detected Fourier-transform excitation spectroscopy scheme, to microscopically map the energy landscape of WSe2. As a test, we addressed WSe2 for which the bright excitons naturally dominate the luminescence response, while dark excitons dominate the current response. This groundwork provides the basis for a new, current-detected approach to study the dynamics of dark exciton states across different materials incl. biomembranes. NanoLett. 25, 7658−7664 (2025); Nature Commun. 16:5184 (2025).
Interestingly, beyond the proposed research, using a novel SPAD camera we succeeded in superior spatio-temporal exciton tracking, at even lower fluence. An important achievement for further success of this project. Diana Dall’Aglio et al., Spatio-temporal exciton tracking with a SPAD camera, ACS Photonics, 12, 1291−1299 (2025). The SPAD camera allows to combine dedicated encoded excitation patterns, with super-resolution and ps time resolution. We are pursuing this direction.
In 2024 we could for the first time find an optimum in the exciton diffusion length of LH2 monolayers (~45 nm) at a critical concentration, not fully packed compared to crystal layer, while with enough proximity to have lifetime reduced from 1 ns to 300 ps. We believe these conditions are very close to the packing in the natural membrane. Moreover, the transport is recorded at sunlight illumination conditions. Still, AFM data so far revealed rather disordered layers, also with the LH2 random top-down and down-top. In collaboration with Sheffield group, but also in house Liguori group we are now (June 2025) working on higher sample control, with defined orientation and packing order.
Using Photoelectrochemical Two-Dimensional Electronic Spectroscopy we recorded the first 2D spectra on plant Photosystem I, providing a 2D-map of the first ps, López-Ortiz et al., Photoelectrochemical Two-Dimensional Electronic Spectroscopy (PEC2DES) of Photosystem I: Charge Separation Dynamics Hidden in a Multichromophoric Landscape, ACS Appl. Mater. Interfaces, 16 (33), 43451 – 43461 (2024).
The photocurrent detected 2DES turned out to compensate terms in its nonlinear response, moreover multi-chromophoric ground state bleach dominated over stimulated emissions. We explained these unexpected contrast issues and proposed effected compressed sensing for effective data collection. Bolzonello et al., Nonlinear Optical Spectroscopy of Molecular Assemblies: What Is Gained and Lost in Action Detection?', J. Phys. Chem. Lett. 14 (50), 11438 – 11446 (2023); Bolzonello et al., Fisher information for smart sampling in time-domain spectroscopy, J. Chem. Phys., 160, 214110 (2024).
To pursue the photocurrent spectroscopy on 2D -material substrate, we engineered dual action spectroscopy, a photocurrent- and luminescence-detected Fourier-transform excitation spectroscopy scheme, to microscopically map the energy landscape of WSe2. As a test, we addressed WSe2 for which the bright excitons naturally dominate the luminescence response, while dark excitons dominate the current response. This groundwork provides the basis for a new, current-detected approach to study the dynamics of dark exciton states across different materials incl. biomembranes. NanoLett. 25, 7658−7664 (2025); Nature Commun. 16:5184 (2025).
Interestingly, beyond the proposed research, using a novel SPAD camera we succeeded in superior spatio-temporal exciton tracking, at even lower fluence. An important achievement for further success of this project. Diana Dall’Aglio et al., Spatio-temporal exciton tracking with a SPAD camera, ACS Photonics, 12, 1291−1299 (2025). The SPAD camera allows to combine dedicated encoded excitation patterns, with super-resolution and ps time resolution. We are pursuing this direction.
In 2024 we could for the first time find an optimum in the exciton diffusion length of LH2 monolayers (~45 nm) at a critical concentration, not fully packed compared to crystal layer, while with enough proximity to have lifetime reduced from 1 ns to 300 ps. We believe these conditions are very close to the packing in the natural membrane. Moreover, the transport is recorded at sunlight illumination conditions. Still, AFM data so far revealed rather disordered layers, also with the LH2 random top-down and down-top. In collaboration with Sheffield group, but also in house Liguori group we are now (June 2025) working on higher sample control, with defined orientation and packing order.
The Structured Excitation Energy Transfer detection is new method developed in the course of this project, we coined StrEET, was result of our near-field attempts with periodic structures. The larger area combined with nanometric structure, allowed us to go many orders of magnitude lower in fluence and break through the sunlight level for transport measurement. An important advance, based in our FastTrack research, reaching far beyond in its final implementation, allowing transport measurements far below annihilation conditions. Also, the application potential is much wider, such that we are contemplating to apply for an ERC PoC grant to explore the application and commercialization potential.
The unexpected contrast of the reported Photoelectrochemical Two-Dimensional Electronic Spectroscopy on plant Photosystem I stimulated us to understand the compensation of terms in its nonlinear response, and the domination of Ground State Bleaching over Stimulated Emission. We published a theoretical proposal paper.
The surprising contrast in incoherent 2DES appeared a comparable obstacle also for several other groups. Therefore, we decided to organize a brainstorm workshop at ICFO in the context of this ERC-project (9-10 feb 2025) focused on Action detected 2D-ES spectroscopy. We invited lead researchers in the field (Martin Zanni, Jennifer Ogilvie, Donatas Zigmantis, Pavel Maly and others) and the 2 days of discussion produced a concrete working road-map to overcome the contrast issues. The discussion results will be published in J.Chem.Phys. Most importantly, for the ERC project we now have an updated technical track to save our second project objective.
Exploring a novel SPAD camera, not yet commercial, in collaboration, combining nm spatial and ps temporal resolution, we succeeded in first single-shot exciton tracking. Definitely a breakthrough, important for this project. The camera was not planned as simply such technology did not exist at the time of writing in 2021. The SPAD camera, together with above StrEET invention, are now emerging as the basis for a PoC application, provided we can find industrial interest.
We determined transport and decay mechanisms in exfoliated TMD crystals, WSe2 and MoSe2, with varying thickness from multilayer down to the monolayer, in collaboration with Tielrooij group from TUEindhoven and Malic group from Uni.Marburg. Adv. Electron. Mater. 10 (2), 24700091 (2024) and Nature Comm. in revision.
The most important scientific advance of the project is the identification of an optimum in the exciton diffusion length of LH2 monolayers, bringing us close to the packing in the natural membrane.
The unexpected contrast of the reported Photoelectrochemical Two-Dimensional Electronic Spectroscopy on plant Photosystem I stimulated us to understand the compensation of terms in its nonlinear response, and the domination of Ground State Bleaching over Stimulated Emission. We published a theoretical proposal paper.
The surprising contrast in incoherent 2DES appeared a comparable obstacle also for several other groups. Therefore, we decided to organize a brainstorm workshop at ICFO in the context of this ERC-project (9-10 feb 2025) focused on Action detected 2D-ES spectroscopy. We invited lead researchers in the field (Martin Zanni, Jennifer Ogilvie, Donatas Zigmantis, Pavel Maly and others) and the 2 days of discussion produced a concrete working road-map to overcome the contrast issues. The discussion results will be published in J.Chem.Phys. Most importantly, for the ERC project we now have an updated technical track to save our second project objective.
Exploring a novel SPAD camera, not yet commercial, in collaboration, combining nm spatial and ps temporal resolution, we succeeded in first single-shot exciton tracking. Definitely a breakthrough, important for this project. The camera was not planned as simply such technology did not exist at the time of writing in 2021. The SPAD camera, together with above StrEET invention, are now emerging as the basis for a PoC application, provided we can find industrial interest.
We determined transport and decay mechanisms in exfoliated TMD crystals, WSe2 and MoSe2, with varying thickness from multilayer down to the monolayer, in collaboration with Tielrooij group from TUEindhoven and Malic group from Uni.Marburg. Adv. Electron. Mater. 10 (2), 24700091 (2024) and Nature Comm. in revision.
The most important scientific advance of the project is the identification of an optimum in the exciton diffusion length of LH2 monolayers, bringing us close to the packing in the natural membrane.