Ultrafast coherent dynamics in photovoltaic bulk heterojunctions

Carlo Andrea Rozzi^a, Elisa Molinari^a^,^h, Ephraim Sommer^b, Sarah Maria Falke^b, Christoph Lienau^b, Antonietta De Sio^b, Daniele Brida^c^,^d, Giulio Cerullo^d, Margherita Maiuri^d, Michele Amato^e, Angel Rubio^f^,^g

^aCNR - Istituto Nanoscienze, Modena, 41125, Italy

^bCarl von Ossietzky Universität,, Oldenburg, 26129, Germany

^cUniversity of Konstanz, Germany, Universitaetsstr. 10, POB M680, Konstanz, 78457, Germany

^dCNR-IFN, Politecnico di Milano, Milano, 20133, Italy

^e Universitè Paris-Sud, Orsay, France

^fUniversidad del País Vasco San Sebastián, San Sebastián, 20018, Spain

^gFritz-Haber-Institut, Berlin, 14195, Germany

^hUniversità di Modena e Reggio Emilia, via Campi 213a, Modena, 41125, Italy

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics 2015 (HOPV15)

Roma, Italy, 2015 May 11th - 13th

Organizer: Filippo De Angelis

Oral, Carlo Andrea Rozzi, presentation 082
Publication date: 5th February 2015

The photoinduced charge-separation events occurring in photovoltaic and light harvesting systems have traditionally been interpreted in terms of the incoherent kinetics of optical excitations and of charge hopping. However signatures of quantum coherence were recently observed in energy transfer in photosynthetic bacteria and algae.[1] However, still very little is known about the role of quantum coherence at room temperature in the earliest stage of the dynamics in technologically relevant organic photovoltaic materials. Recent experiments found evidence for an ultrafast long-range charge separation in such systems but could not differentiate between coherent and incoherent charge-transfer models.[2] We have studied charge separation in molecular systems for artificial photosynthesis and in a bulk P3HT:PCBM blend. By combining TDDFT simulations of the quantum dynamics and high time resolution femtosecond spectroscopy, we provide evidence that the coherent coupling between electronic and nuclear degrees of freedom is of key importance in triggering charge delocalization and transfer both in covalently bonded molecules[2] and in non-bonded bulk heterojunctions[3]. We have exploited the results of our research to design, syntesize and characterize a novel molecular scaffold for photovoltaic applications.[4]
Frames taken from the quantum simulation of a portion of an organic solar cell composed by a polymer chain, and a Fullerene buckyball. The two parts of the system, separated by a small space, act as the poles of a microscopic Sun-operated battery. The quantity depicted illustrates the wavelike oscillations of an electron after Sun light is absorbed at time 0. The time scale is in femtoseconds (fs).
[1] Engel, G. S. et al. Nature 446, 782-786 (2007) [2] S. Gélinas et al., Science 343, 512–516 (2014) [3] Rozzi C. A. et al., Nat. Comm 4, 1602 (2013) [4] Falke S. et al., Science 344, 1001 (2014) [5] Pittalis S., et al., Adv. Func. Mat. (2014)

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.