2026/06/26
Préparation et caractérisation de mélanges photoactifs pour la photovoltaïque organique et l’impression 3D
Martel, A. (2026). Préparation et caractérisation de mélanges photoactifs pour la photovoltaïque organique et l’impression 3D. Thesis.
In light of the challenges associated with the energy transition and the ongoing pursuit of enhanced energy conversion device performance, the development of functional materials is experiencing considerable growth. Among these, π-conjugated organic compounds stand out for their tunable optoelectronic properties and their durability in advanced optoelectronic devices such as organic solar cells and light-emitting diodes. In this context of improving the efficiency and processability of the active layers of these devices, this thesis focuses on the preparation and characterization of photoactive mixtures for organic photovoltaics and 3D printing. The main objective is to establish structure-processing-property relationships for formulations based on aromatic π-conjugated systems for thin films and 3D architectures. Firstly, the section on organic photovoltaics is divided into two parts, ranging from the state of the art to experimental advances made in the laboratory. On the one hand, a book chapter was written to present recent literature on organic photovoltaics under indoor lighting conditions. On the other hand, the influence of the conformational rigidity of non-fullerene acceptors (NFA) and the length of their carbon chains on the optoelectronic properties of the mixture was studied, showing that more rigid linear structures with moderately long carbon chains offer superior performance in terms of fluorescence quenching and solubility than angular structures with shorter chains. Nevertheless, photovoltaic efficiency results showed that the integration of a rigid NFA is not favorable, as it limits molecular rearrangement during the deposition and solidification of the active layer, hindering microstructure optimization. Next, photopolymerizable formulations incorporating carbazole derivatives were developed and evaluated for their potential in 3D printing using masked stereolithography apparatus (mSLA). The structure of carbazoles influences emission intensity and maxima position, depending on the length of the aliphatic chain and the proximity of unsaturations to the carbazole core, respectively. In photopolymerized covalent mixtures, the polarity/flexibility of the crosslinking agent causes a slight spectral shift, suggesting an influence of the local environment on the photophysical properties of carbazole. The choice of photoinitiator influences the kinetics and depth homogeneity of curing, which are crucial parameters in 3D printing. These can also be influenced by the polarity/flexibility of the crosslinking agent. Finally, the last part focuses on the synthesis and characterization of photochromic compounds intended for vat photopolymerization using mSLA technology, with the aim of exploiting the photochromic functionality of these chromophores in 3D printing.