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PHOto-induced Energy flow in Bio-inspired molecular circuits probed with Ultrafast two-dimensional Spectroscopy

Periodic Reporting for period 2 - PHOEBUS (PHOto-induced Energy flow in Bio-inspired molecular circuits probed with Ultrafast two-dimensional Spectroscopy)

Reporting period: 2017-10-01 to 2018-09-30

PHOEBUS aims to investigate the molecular mechanisms of photosynthesis in order to produce artificial molecular circuits able to mimic the natural mechanism of energy production. The absorption of light by the molecules contained in the photosynthetic organisms occurs within infinitesimal fractions of seconds. The initial photo-excitation caused by sunlight is efficiently distributed over the molecules and it is transmitted through a pigment energy-cascade to the “power station” of the photosynthetic organism, as in a solar cell. In this framework, PHOEBUS has photographed these mechanisms through sophisticated instruments, available at the Politecnico di Milano and at Princeton University, that allowed generating flashes of femtosecond laser light, to provide the design of innovative chemical structures (molecular circuits) that can control in sophisticated ways the flow of excitation energy.
The project focuses on bio-inspired molecular circuits, where several light-absorbing molecules are linked together to form antenna systems displaying ultrafast electronic energy transfer (EET). We aim to identify and understand how coherence can direct, control, and optimize energy flow after photo-excitation. PHOEBUS aimed at answering the following questions: (i) does coherent coupling influence excitation transport compared to incoherent hopping of excitation? (ii) how can we design chemical structures that use coherence in light harvesting?
The project, once completed, will contribute to the field of solar-energy-conversion technologies. Its results will be used as rules to design artificial complexes that efficiently direct and regulate the excitation energy flow,with the ultimate goal to be used as smart solution for antenna devices. Indeed the multi-molecular arrays here studies will be used for efficient harvesting and concentration of sunlight, which is the initial phase of solar fuel production. These organic-based systems could be be used to: (i) optimize light absorption cross sections of organic photovoltaic (OPV) devices, (ii) transport energy over long distances. These new materials might have a significant impact in the field of OPV, supported by the forecast that the OPV market will rise from $4.6 million (calculated in 2012) to $ 630 million in 2022 (IDTechEx estimation).
"●PHOEBUS produced the following outcomes:
1- Development of an ultrafast pump-probe spectrometer at Princeton University, convertible into a 2D set-up in the partially collinear geometry. (completed)
2- Optimization of the broadband 2DES visible set-up in the boxcar geometry. (completed)
3- Developement of an ultrafast broadband pump-probe apparatus coupled with high magnetic field (up to 25T)
at the National High Magnetic Field Laboratory facility in Tallahassee, FL. (completed, publication on JPCL (2018))
4- Ultrafast pump-probe spectroscopy on genetically modified light-harvesting complexes from a sulfur bacteria
to study the role of the coherent coupling between electronic transitions and the molecular vibrations. (completed,
publication on Nature Chemistry ( 2018))
5- Pump-probe on an artificial ligh-harvesting dyad which models both the energy and the electron transfer
mechanism as in a reaction center of a photosynthetic complex. (completed, publication on PCCP (2017))
6- Preliminary pump-probe experiments on arrays of perylene-based molecules (PDI) arranged in a tetrameric configuration
to study the energy transfer process. (ongoing collaboration with Castellano's group)

●The dissemination of the results is following the guidelines described in the DoA:
- PHOEBUS website can be found at
- Participation at several outreach events: “Meet me tonight” event, Milan (September, 2018)
""FRIC:Female Researchers in Chemistry (FRIC)"" periodic meetings with young female students to support women in STEM through networking and empowerment at Frick Laboratory, Chemistry Dept. Princeton (2015-2017)

●Participation at several Conferences, here the main ones are listed:
1. M. Maiuri “Coherent Charge Transfer in Organic Photovoltaics probed by ultrafast spectroscopies” Optical Probes in Conjugate Polymers, 2015 Hong Kong. (Invited)
2. M. Maiuri et al. Light Harvesting Processes 2015, Kloster Banz, Germany. (Oral)
3. M. Maiuri et al. Ultrafast Phenomena, 2016, Santa Fe, USA. (Poster)
4. M. Maiuri et al. Ultrafast Phenomena, 2016, Santa Fe, USA. (Oral)
5. M. Maiuri et al. EFRC-Hub-CMS PI Meeting, 2017, Washington D.C. USA. (Oral)
6. M. Maiuri et al. Ultrafast Phenomena, 2018, Hamburg, Germany (Poster)
7. L. Moretti et al. and M. Maiuri, ESP conference, 2018, Santa Fe’, USA (Poster)
8. L. Moretti et al. and M. Maiuri, EOSAM conference, 2018, Delft, Nederland (Oral)

●The exploitation and communication of the results to non-scientific public happened through:
(1) Princeton Chemistry Press Release on Marie Curie Fellowship
(2) Interview for the NHMFL website “What goes into the magnet”
(3) Editorial Article on Chemistry of Materials “Matter of light or light for matter”
M. Maiuri, D. Meroni “Photoactive Materials in the Year of Light: Light for Matter or Matter of Light?”, Chemistry of Materials 28, 409-410 (2016).
(4) Various Press Releases articles (in English or Italian) on PHOEBUS by Politecnico di Milano (Beneficiary Institutions):
(5) Interview on “La Repubblica”:
(6) Several Interviews for the prize “L’Orèal-UNESCO Women for Science”

PHOEBUS contributed to European excellence and competitiveness as:
(a) Key research: development of 2DES techniques, still not widely diffused
(b) Enhancement of ERA: the setup developed in the returning phase will be used in the frame of Laserlab (‘Integrated
Initiative’ of European Laser Research Infrastructures) in the Energy Area.
(c) Advancement of Energy Challenge by the identification of potential chromophores for efficient solar harvesting
Moreover the acquired experimental (2DES) and theoretical (quantum calculations) skills during the outgoing phase will represent a milestone per se,
since they can allow to extend this cutting-edge methodology to study other type of systems, possibly with high impact on life science (such as DNA and proteins).