I joined the theory group at the Max Planck Institute for Polymer Research as a Postdoctoral fellow in March 2018. In my current research, I am focusing on the design of non-fullerene acceptors for organic sollar cells.
I obtained my PhD in Physics from Moscow State University in 2017, under the supervision of Prof. V. Ivanov. My research addressed a hybrid simulation scheme which combines the fast equilibration on long times and large scales and the ability to account for the details of the chemical structure of molecules. As an intern, I worked in Schlumberger Moscow Research Center on a project aimed to improve the estimation methods of storage capacity and hydrocarbon flow through nanopores. I obtained my Diploma with Honours in Condensed Matter Physics (Polymer Physics) from Moscow State University in 2014.
N-type Doping of the Organic Non-Fullerene Acceptor O-IDTBR Leads to Transistors with Electron Mobility in Excess of 1 cm2 V-1s-1
A. F. Paterson, R. Li, A. Markina, L. Tsetseris, S. MacPhee, H. Faber, A.‑H. Emwas, J. Panidi, H. Bristow, D. Baran, D. Andrienko, M. Heeney, I. McCulloch, Th. D. Anthopoulos
Charge Photogeneration in Non-Fullerene Organic Solar Cells: Influence of Excess Energy and Electrostatic Interactions
M. Saladina, P. S. Marques, A. Markina, S. Karuthedath, C. Woepke, C. Goehler, Y. Chen, M. Allain, P. Blanchard, C. Cabanetos, D. Andrienko, F. Laquai, J. Gorenflot, C. Deibel
Advanced Functional Materials,
In organic solar cells photogenerated singlet excitons form charge transfer (CT) complexes which subsequently split into free charge carriers. Here we consider the contributions of excess energy and molecular quadrupole moments to the charge separation process. We investigate charge photogeneration in two separate bulk heterojunction systems consisting of the polymer donor PTB7-Th and two non-fullerene acceptors ITIC and h-ITIC. CT state dissociation in these donor--acceptor systems is monitored by charge density decay dynamics obtained from transient absorption experiments. We study the electric field dependence of charge carrier generation at different excitation energies by time delayed collection field (TDCF) and sensitive steady-state photocurrent measurements. Upon excitation below the optical gap free charge carrier generation becomes less field dependent with increasing photon energy which challenges the view of charge photogeneration proceeding through energetically lowest CT states. We determine the average distance between electron--hole pairs at the donor--acceptor interface from empirical fits to the TDCF data. The delocalisation of CT states is larger in PTB7-Th:ITIC the system with larger molecular quadrupole moment indicating the sizeable effect of the electrostatic potential at the donor--acceptor interface on the dissociation of CT complexes.
Long-range exciton diffusion in molecular non-fullerene acceptors
Y. Firdaus, V. M. Le Corre, S. Karuthedath, W. Liu, A. Markina, W. Huang, S. Chattopadhyay, M. M. Nahid, M. I. Nugraha, Y. Lin, A. Seitkhan, A. Basu, W. Zhang, I. McCulloch, H. Ade, J. Labram, F. Laquai, D. Andrienko, L. J. A. Koster, T. D. Anthopoulos
The short exciton diffusion length associated with most classical organic semiconductors used in organic photovoltaics (5-20 nm) imposes severe limits on the maximum size of the donor and acceptor domains within the photoactive layer of the cell. Identifying materials that are able to transport excitons over longer distances can help advancing our understanding and lead to solar cells with higher efficiency. Here we measure the exciton diffusion length in a wide range of nonfullerene acceptor molecules using two different experimental techniques based on photocurrent and ultrafast spectroscopy measurements. The acceptors exhibit balanced ambipolar charge transport and surprisingly long exciton diffusion lengths in the range of 20 to 47 nm. With the aid of quantum-chemical calculations we are able to rationalize the exciton dynamics and draw basic chemical design rules particularly on the importance of the end-group substituent on the crystal packing of nonfullerene acceptors.
Barrierless Free Charge Generation in the High-Performance PM6:Y6 Bulk Heterojunction Non-Fullerene Solar Cell
L. Perdigon-Toro, H. Zhang, A. Markina, J. Yuan, C. M. Wolff, M. Stolterfoht, Y. Zou, F. Gao, D. Andrienko, S. Shoaee, D. Neher
Organic solar cells (OSCs) are currently experiencing a second golden age thanks to the development of novel non-fullerene acceptors (NFAs). Surprisingly some of these blends exhibit high efficiencies despite a low energy offset at the heterojunction. Herein we thoroughly investigate free charge generation in the high-performance blend of the donor polymer PM6 with the NFA Y6 as a function of internal field temperature and excitation energy. Results show that generation is essentially barrierless with near-unity efficiency regardless of excitation energy. Efficient generation is maintained over a wide temperature range down to 100 K despite the small driving force for charge generation. Studies on a blend with a low concentration of the NFA measurements of the energetic disorder and theoretical modelling suggest that charge generation is assisted by the electrostatic interfacial field which for Y6 is large enough to compensate the Coulomb dissociation barrier. This field also repels charges from donor-acceptor interfaces reducing non-geminate recombination.
Intrinsic efficiency limits in low-bandgap non-fullerene acceptor organic solar cells
S. Karuthedath, J. Gorenflot, Y. Firdaus N. Chaturvedi, C. S. P. De Castro, G. T. Harrison, J. I. Khan, A. Markina, A. H. Balawi, T. A. D. Pena, W. Liu, R.-Z. Liang, A. Sharma, S. H. K. Paleti, W. Zhang, Y. Lin, E. Alarousu, D. H. Anjum, P. M. Beaujuge, S. De Wolf, I. McCulloch, T. D. Anthopoulos, D. Baran, D. Andrienko, F. Laquai
In bulk heterojunction (BHJ) organic solar cells (OSCs) both the electron affinity (EA) and ionization energy (IE) offsets at the donor–acceptor interface should equally control exciton dissociation. Here we demonstrate that in low-bandgap non-fullerene acceptor (NFA) BHJs ultrafast donor-to-acceptor energy transfer precedes hole transfer from the acceptor to the donor and thus renders the EA offset virtually unimportant. Moreover sizeable bulk IE offsets of about 0.5 eV are needed for efficient charge transfer and high internal quantum efficiencies since energy level bending at the donor–NFA interface caused by the acceptors’ quadrupole moments prevents efficient exciton-to-charge-transfer state conversion at low IE offsets. The same bending however is the origin of the barrier-less charge transfer state to free charge conversion. Our results provide a comprehensive picture of the photophysics of NFA-based blends and show that sizeable bulk IE offsets are essential to design efficient BHJ OSCs based on low-bandgap NFAs.