Research
Chirality-Induced Spin Selectivity
About two decades ago, it was found that when electrons pass through chiral molecules their spin is preferentially transmitted - parallel or antiparallel to the electron transfer displacement vector - depending on the chirality of the molecular layer. This phenomenon is called chirality-induced spin selectivity (CISS) effect. Following pioneering works on self-assembled monolayers of chiral amino acids or polypeptides on gold, a variety of strategies have been employed to test the CISS effect in the transport of the electrons injected in spintronic devices under the application of an external electric field. However, only recently, the possibility of promoting the CISS effect through the use of light excitation has been proposed. My research aims to provide direct access to CISS at the molecular level in chiral donor/acceptor dyads by studying the photoinduced electron transfer via transient optical and electron paramagnetic resonance (EPR) spectroscopies.
Relevant publications:
1. A. Privitera, …, R. Sessoli, Chem. Eur. J. 2023, e202301005
2. A. Chiesa, A. Privitera, …, S. Carretta, Adv. Mater. 2023, 2300472
3. A. Privitera, …, R. Sessoli, Chem. Sci. 2022, 13, 12208-12218
Spin Processes in Organic Photovoltaics
Organic photovoltaics (OPV) holds outstanding potential to develop clean, sustainable and low-cost energy. In recent years, the search for OPV devices possessing commercially relevant efficiencies and lifetimes has received tremendous impetus thanks to the discovery of the critical role of spin-bearing species. Most recent results have demonstrated that charge recombination pathways leading to triplet excitons significantly affect voltage losses and intrinsic stability to light even in best-performing OPV devices. My research focuses on the investigation and control of spin photophysical pathways in organic solar cells to ultimately foster their commercialization.
Relevant publications:
1. A. Privitera, …, A. Gillett, Adv. Energy Mater. 2022, 12, 2103944
2. A. Gillett, A. Privitera, …, R. H. Friend, Nature 2021, 597, 666–671
3. I. Ramirez, A. Privitera, … M.Riede, Nat. Commun. 2021, 12, 471
Molecular Doping and Spin Transport
The precise control of the charge carrier density and conductivity of organic semiconductors through molecular doping has been critical for the successful commercialization of organic optoelectronic devices. In the last few years, molecular doping has attained renewed interest sparked by the recent advancements that clarified the elementary steps occurring at the molecular level. These steps are characterized by the presence of unpaired electron spins (S=1/2). Taking advantage of the electron spin to investigate molecular doping represents a new perspective from which to study charge generation and transport in doped layers.
Relevant publications:
1. A. Privitera, …, M. Riede, Adv. Optical Mater. 2021, 2100215
2. A. Privitera, …, M. Riede, J. Mater. Chem. C 2021, 9, 2944 - 2954
3. A. Privitera, …, D. Beljonne, Adv. Funct. Mater. 2020, 30, 2004600
Spin Physics of Hybrid Nanostructures
Quantum dots (QDs) represent semiconductor particles with dimensions in the nanometer range, featuring unique optical and electronic properties. They are a central topic in nanotechnology and materials science. QDs can be fabricated from diverse materials, including III-V semiconductors, perovskite, and carbon. Furthermore, they can be combined with different systems, e.g. organic semiconductors. Upon photoexcitation, QDs can be excited to a higher energy state, opening a myriad of potential pathways. Many of these involve spin states. My research uses EPR spectroscopies to investigate these photophysical processes with a specific focus on photovoltaic applications.
Relevant publications:
1. M. Righetto, A. Privitera, …, R. Bozio, Nanoscale 2018, 10, 11913-11922
2. A. Privitera, …, L. Franco, J. Phys. Chem. Lett. 2017, 8, 5981−5986
3. A. Privitera, …, L. Franco, Phys. Chem. Chem. Phys. 2016,18, 31286-31295