PhD position (M/F) : Quantum Mechanical Investigation of Light-to-Mechanical Energy Conversion in Molecular Photoswitches.

Job Description

Thesis Subject

Polymer-Based PhotoActuators (PPAs) are polymer matrix materials doped with molecular photoswitches. Upon irradiation, PPA films undergo a reversible macroscopic mechanical deformation, making them attractive systems for the transduction between light and mechanical energy, with possible applications in motors, drug delivery devices, textiles and electrical generators. Recent experimental studies demonstrated a quantitative correlation between the molecular photoswitch properties and the photomechanical effect.1 In addition, material structuration plays a crucial role both at the supramolecular scale (through interactions between the photoswitch and the polymer chains) and at the microscale, enabling the conversion of molecular deformation into local strain and ultimately macroscopic actuation.

The SIMULACTOR project aims to develop an integrated multiscale approach to model the mechanical behavior of PPAs. Its objective is to understand and optimize PPA properties using a simulation strategy that spans from the molecular scale (ab initio calculations) to continuum approaches, thereby accounting for the different levels of complexity present in real materials. The PhD student will focus on the molecular scale to model and optimize the optical and mechanical properties of both the photoswitch and the photomorphon (the photoswitch and its neighboring polymer chains), the latter governing how the photoinduced strain is transmitted to the surrounding material through photochrome/polymer interactions.

To this end, quantum mechanical (QM) methods will be employed. The PhD student will first) assess the efficiency of light-to-mechanical energy conversion by adapting excited-state mechanochemical analyses2 to quantify the fraction of absorbed light energy effectively converted into mechanical work. In parallel, the influence of the local polymer environment (the “photomorphon”) on photoswitch performance will be investigated using non-adiabatic molecular dynamics3 and QM/MM simulations. By comparing isolated molecules with polymer-embedded systems, the project will clarify how intermolecular interactions influence photoreactivity and mechanical output. Overall, this work will enable the screening and rational design of optimized photoswitch/polymer combinations4 and will lay the groundwork for future PPA materials design.

The candidate should hold a Master's degree in Chemistry, Physical Chemistry, or Physics. A strong background in physical chemistry is required, and prior experience in computational chemistry would be an asset. The candidate must have completed a research project (Master's internship) in theoretical chemistry, molecular modeling or computational chemistry.

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[1] Arroyo, I et al. Small 2024, 20 (46), 2402131. [2] Stauch, T.; Dreuw, A. J. Phys. Chem. Lett. 2016, 7 (7), 1298–1302. [3] Oruganti, B.; Wang, J.; Durbeej, B. J. Org. Chem. 2022, 87 (17), 11565–11571. [4] (a) Le Bras, L.; Lemarchand, C.; Aloïse, S.; Adamo, C.; Pineau, N.; Perrier, A. J. Chem. Theory Comput. 2020, 16 (11), 7017–7032 https://doi.org/10.1021/acs.jctc.0c00762. (b) Villegas, O.; Serrano Martínez, M.; Le Bras, L.; Ottochian, A.; Pineau, N.; Perrier, A.; Lemarchand, C.. Macromolecular Theory and Simulations 2024, 33 (6), 2400033. https://doi.org/10.1002/mats.202400033 (c) Serrano Martínez, M.; Pineau, N.; Lemarchand, C.; Perrier, A. Phys. Chem. Chem. Phys. 2025, 27 (44), 23669–23684. https://doi.org/10.1039/D5CP02807H.

Your Work Environment

This PhD proposal is part of the SIMULACTOR project, funded by the French National Research Agency (ANR) under the PEPR LUMA program.
The SIMULACTOR consortium brings together specialists in quantum calculations applied to photochromic systems (LIED, Université Paris Cité), experts in classical atomistic simulations (molecular dynamics and coarse-graining, LMCE, CEA/DAM/DIF), as well as specialists in continuum simulations (finite element methods, discrete element methods, IML, Université de Lille).

The PhD candidate will work at the Laboratoire Interdisciplinaire des Énergies de Demain (LIED, CNRS, Université Paris Cité), located at Université Paris Cité, 75013 Paris. The LIED aims to develop both fundamental and applied research addressing the challenges of energy and climate transitions. In this context, the laboratory promotes a comprehensive approach based on a unique multidisciplinary methodology, bringing together researchers in biology, chemistry, physics, computer science, as well as the humanities and social sciences. The LIED offers a unique and stimulating scientific environment, structured around team meetings, laboratory seminars, and interdisciplinary public seminars focused on energy and transition-related topics.

The PhD candidate will join the “Climate and Energy in Urban Environments” team, which brings together chemists and physicists (6 permanent members) with complementary expertise. Within this group, the PhD candidate will work directly with Prof. Aurélie Perrier, specialist in computational photochemistry, and will interact closely with all members of the SIMULACTOR consortium. The quantum chemistry codes required for the project are available, along with access to both local and national computing resources.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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