There is a growing interest in conjugated polymers, now found in most organic electronic devices. However, their preparation most of the time relies on precious metal catalysed reactions with poor atom economy and prone to introduce defects. The PhotoSynth project offers to prepare conjugated polymers with an excellent atom economy, condensing a diaminoPDI and an aldehyde together to form a poly-imine further irreversibly photo cyclized by visible light (for example in a continuous flow photo reactor) into a fully conjugated system. This approach limits waste, the use of additive, removes the need for expensive catalyst or ligands and is also versatile as the diaminoPDI building block can be combined with a wide variety of opto/electroactive bis-adehydes to tune the properties of the polymers, which will be later tested in devices. PhotoSynth paves the way toward a sustainable, modular and efficient synthesis of a new generation of organic semiconductors of interest.

Perovskite solar cells (PSCs) have become a trending technology in photovoltaic research due to a rapid increase in efficiency in recent years. In 2020, a record efficiency of 25.5% close from Shockley-Queisser theoretical limit of 30% was reported. Tandem solar cells offer an alternative to go beyond but stability still remains an issue. In our project, we will bring together our complementary expertise in molecular and macromolecular syntheses, thin film morphology tuning and cell device engineering to improve the stability of highly efficient inverted perovskite cells using new electron transport layers (ETL) with high electron mobility and high stability. We will design and synthesize new n-type fullerene free semiconductors. Introduction of cross-linkable groups will lead to stabilized ETLs by thermally-induced cross-linking after film formation. The efficiency and stability of these ETLs will be finally evaluated through their incorporation in tandem configuration.

Organic electronics, pipe-dream few decades ago, is now a reality with commercially available Organic light emitting diode based displays (TVs, smartphones), sensors, batteries or photovoltaics (OPVs). Hence, the advent of such research field has generated a craze in the scientific community leading to the synthesis and characterization of various classes of pi-conjugated molecular and macromolecular semiconductors. Among them, imide-containing rylenes have attracted considerable research attention due to their redox, electron-withdrawing and charge-carrier transport properties, as well as their excellent chemical, thermal, and photochemical stabilities. Naphthalene diimide (NDI) and perylene diimide (PDI) can be unequivocally recognized as the most studied imide based building blocks for the preparation of high-performance electron transporting optoelectronic materials. Within these wide-ranging studies, considerable effort has been undertaken to functionalize both the bay positions and the nitrogen atom constituting the imide group (N-positions) to bring solubility, tune the molecular (opto)electronic characteristics, and build extended ?-conjugated architectures. A contrario, the N-(alkyl)benzothioxanthene-3,4-dicarboximide (BTXI), a sulfur containing rylene-imide dye, has not triggered such research interest. Among the very scarce publications, the later was exclusively dedicated to its remarkable fluorescent properties in biological and polymer staining applications. Moreover, from a chemical point of view, the BTXI was solely functionalized on the N-position for post-grafting purpose and/or to increase solubility resulting, once again due to a lack of interest, in limited range of characterizations and applications. In this context, and base on self-initiated fundamental work on the selective mono-bromination of the BTXI core, the aim of the BTXI-APOGEE project is to explore different synthetic methodologies to further functionalize the BTXI core, thus leading to the characterization of new and original molecular and macromolecular derivatives which will be finally embedded in specific devices namely OLEDs and organic solar cells.

The PANDEMIC project aims at the incorporation of electroactive moieties in porous crystalline materials. Multi-functional materials – porous, crystalline and conducting – will be devised using the rationale provided by the metal-organic frameworks (MOFs) synthetic strategies precepts. These will allow the controlled organization of the electroactive cores by strong metal-ligand interactions, in order to maximize the overlap between the electroactive pi-cores of the organic parts, and therefore the conduction properties of the obtained materials. Developed since the end of the eighties, MOFs – formed by the controlled self-assembly of inorganic and organic moieties – offer limitless possibilities to develop new materials for precise purposes, depending not only on the properties of the organic/inorganic moieties used, but also on the 3-D structural organization of the building blocks within the material. MOFs are well-known for their high and tunable porosity, making them good candidates for gas storage and capture, or heterogeneous catalysis. On the other hand, MOFs showing both excellent electron conduction and porosity are scarce in the literature, despite the fact that the development of materials combining these two properties would lead to cutting-edge functionalities and applications, e.g. as sensors or battery electrodes. Considering the high level of knowledge on conducting materials in MOLTECH, it is expected for the laboratory to bring its insights into this emerging field. Most of the literature reported conducting MOFs are based on Tetrathiafulvalene (TTF), benzene hexathiolate or phenolates, while MOLTECH reported organic crystalline (semi/supra)conductors with a large set of organic building blocks, thus expanding the scope of materials in this field. The same outcome is expected in the field of MOFs if MOLTECH expertise is added to it: an expansion of the set of materials and the discovery of exciting new highly conducting & porous materials.

As stated in the National Strategy for Research report (SNR, Action Plan 2017, ANR Call), while presenting one of the five priorities of Challenge 3 "Industrial Renewal" (Orientation 14 "Design of new materials"): "The future industry will rely, in part, on multi-functional materials and on integrated measurement and detection systems. These will be all the more efficient as the integration of their functions at different scales (micro-macro) and their assembly will be thought from the nanometric scale". The SIPAIE project is precisely proposed in this context, with the ambition to contribute to a better understanding of the phenomena guiding the structuring process of self-assembled architectures. Aggregation Induced Emission, which was discovered in 2001, is a paradigm shift for luminescence with very promising applications. In this novel photophysical phenomenon, weakly luminescent chromogens in solution become highly emissive in the aggregate or solid state. Consequently, aggregation is no more a threat for fluorophore based application. During the past decade, the AIE mechanisms have been deciphered and can now mostly be resume in one acronym: RIM i.e. Restriction of Internal Motion. AIE is an extremely competitive field of research. Looking at the literature it appears that the AIE mechanisms have more or less come to a consensus without systematic studies at the single aggregate level. The main scientific hypothesis and innovative character of the SIPAIE project are that systematic photo-physics studies at the single particle level will bring new insights on the AIE mechanisms, in particular, the aggregation process, that could lead to even more efficient AIE materials. The SIPAÏE project has two main goals. - The first one, more fundamental, aims at getting a better understanding of the photophysical mechanisms inside AIE aggregates through original systematic measurements at the single aggregate level in solution inside microfluidic devices. - The second one, more applied, aims at nanofabricating calibrated AIE aggregates. We will use a lab-on-chip based on “T-junctions” where two reactants are mixed under a laminar flow with a precise control of the aggregation reaction (temperature, AIEgen concentration, water to AIEgen solvent ratio). An optical confocal filtering system permits to analyze only one class (i.e. size) of aggregates at a time. The evolution of the spectral properties (intensity, spectrum, lifetime, polarization) with respect to the size of the AIE aggregates will be used to assemble reproducible and efficient AIE material. Various new AIGen molecules based on distyrylfuran have already been synthesized and will be analyzed at the single aggregate level concurrently with the two archetypal and commercially available AIEgens: HPS and TPE. We will build an automated and ultra-sensitive OptoFluidic Characterization Platform (OFCP) that will firstly be tested and calibrated with a well-characterized mock-up system : the dimerization of plasmonic nanoparticles. The OFCP will be used to understand the influence of temperature, AIEgen concentration, water to AIEgen solvent ratio, on the size and the spectral properties of AIE aggregates and also the AIEgen aggregation mechanisms at the single particle level. Then the same optofluidic device will be used to prepare AIE solid materials and AIE nanoparticled (know as AIE dots) made from calibrated AIE aggregates inside microfluidic channels. These samples will be thoroughly characterized (AFM, SNOM, NLO) with the collaboration of my teammates.