current research

Adaptation of domain agnostic AI algorithms for the simulation of strongly disordered matter.

Specific research topics of interest to the group:

Organic Electronics

A. Amorphous conjugated polymers

Organic conjugated polymers are a class of cost-effective, mechanically flexible materials which hold promise for innovative technologies ranging from wearable electronics and photovoltaic solar energy harvesting devices to miniature electronic circuits with unique properties. In contrast to silicon, and other crystalline materials commonly used in electronic devices, films made with conjugated polymers offer a rich palette of morphological conformations. I construct theoretical models which capture the effects of morphology on the behavior of excitons in disordered aggregates of conjugated polymers.

Key publications:

  • Relating Chromophoric and Structural Disorder in Conjugated Polymers. L Simine, PJ Rossky, The Journal of Physical Chemistry Letters 8 (8), 1752-1756 (2017)
  • Direct observation of substituted polythiophene planarisation via side-chain alignment. D Raithel, L Simine, S Pickel, K Schötz, F Panzer, S Baderschneider, D Schiefer, R Lohwasser, J Köhler, M Thelakkat, M Sommer, A Köhler, PJ Rossky, R Hildner, PNAS, 115 (11) 2699-2704 (2018)

B. Single molecule junctions

Molecular junctions are the ultimate minimal electronic circuits in which single molecules act as key active and passive components: conductors, rectifiers, diodes, electron/spin/heat pumps. I study the effects of many-body interactions, quantum coherence, and dissipation on non-equilibrium dynamics using minimal models of molecular junctions.

Key publications:

  • Electronic noise due to temperature difference in atomic-scale junctions, O Shein Lumbroso, L Simine, A Nitzan, D Segal, and O Tal, accepted to Nature (2018)
  • Vibrational cooling, heating, and instability in molecular conducting junctions: Full counting statistics analysis. L Simine and D Segal, Physical Chemistry Chemical Physics 14 (40), 13820-13834 (2012)
  • Path-integral simulations with fermionic and bosonic reservoirs: Transport and dissipation in molecular electronic junctions. L Simine and D Segal, The Journal of Chemical Physics 138, 214111 (2013)

Nano-bio interface

Optogenetics uses optically responsive biological molecules to detect and control key processes happening in living cells, for example, the propagation of action potentials in neurons. When it comes to detection, the key challenges at this stage revolve around improving signal-to-noise ratio, tissue penetration depth, and extending the range of reported information, e.g., not only detect the event of action potential, but also the threshold voltage. This requires the modification and optimization of optically responsive proteins with the constraint that the modification of the protein sequence through mutations is the main engineering tool available for this task. I develop the theoretical framework for cost-effective modelling of practically relevant processes, for example, fluorescence quenching through mechanical perturbation of the protein (compression).

Key publications:

  • Fluorescent protein detects host structural rearrangements via electrostatic mechanism. L Simine, H Lammert, L Sun, J N Onuchic, P J Rossky, J. Am. Chem. Soc. Comm., 140 (4), 1203 (2018)

Future directions:

  • mechanistic studies of existing probes (e.g., ArcLight, ASAP1), strategies for improving signal to noise ratio and penetration depth into the tissue (e.g., intra-molecular singlet fission)
  • Bio-interface between conducting polymers and neural tissue