With power conversion efficiency surpassing the 10% milestone for commercialization, photovoltaic technology based on solution-processable polymer solar cells (PSCs) provides a promising route towards a cost-efficient strategy to address the ever-increasing worldwide energy demands. However, to make PSCs successful, challenges such as insufficient light absorption, high maintenance costs, and relatively high production costs must be addressed. As solutions to some of these problems, the unique properties of nanostructured materials and complimentary light absorption in multi-junction device structure could prove to be highly beneficial. As a starting point, integrating nanostructure-based transparent self-cleaning surfaces in PSCs was investigated first. By controlling the length of the hydrothermally grown ZnO nanorods and covering their surface with a thin layer of chemical vapor-deposited SiO2, a highly transparent and UV-resistant superhydrophobic surface was constructed. Integrating the transparent superhydrophobic surface in a PSC shows minimal impact on the figure of merit of the PSC. To address the low mechanical durability of the transparent superhydrophobic surface based on SiO2-coated ZnO nanorods, a novel method inspired by the water condensation process was developed. This method involved directly growing hollow silica half-nanospheres on the substrate through the condensation of water in the presence of a silica precursor. Benefit from the decreased back scattering efficiency and increased light transport mean free path arise from the hollow nature, a transparent superhydrophobic surface was realized using submicrometer sized silica half-nanospheres. The decent mechanical property of silica and the “direct-grown” protocol are expected to impart improved mechanical durability to the transparent superhydrophobic surface. Regarding the application of multi-junction device structure in PSCs, homo multi-junction PSCs were constructed from an identical polymer absorber, in which the homo-tandem device showed an enhanced power conversion efficiency (PCE) (8.3% vs 7.7%) relative to the optimized single junction PSC. The high open voltage (>1.8 V) achieved in homo-tandem PSCs allowed for water splitting with an estimated solar-to-fuel conversion efficiency of 6%. Lastly, a hybrid tandem cell was also constructed using a polymer and a colloidal quantum dot subcell. Different hybrid tandem device architectures were proposed and show a promising PCE of 6.7%.

Ce travail s'appuie sur un nouveau bilan concernant les 70 structures en creux mésolithiques du site du « Parc du Château » à Auneau (Eure-et-Loir), datées entre 8 000 et 5 500 ans avant J.-C. Leurs fonctions variées — sépultures, dépôts intentionnels de restes animaux, foyers en fosse, calages de poteau, extraction, stockage, dépotoirs — évoquent des installations d'une certaine durée. Une enquête étendue à une bonne partie de l'Europe permet de recenser plus d'une centaine d'autres sites mésolithiques livrant des structures analogues, parfois en grand nombre. Il en ressort une image très éloignée de la vision traditionnelle de ces sociétés (cf. chasseurs-collecteurs très mobiles aux campements temporaires sommairement aménagés). Deux types de structures retiennent particulièrement l'attention : les fosses destinées au stockage alimentaire enterré (cf. silos) laissent envisager une consommation différée de fruits à coque (noisettes, glands) permettant de s'affranchir des cycles saisonniers ; les fosses-dépotoirs attestent, quant à elles, une gestion des déchets évoquant des installations durables. On en déduit que le développement de stratégies de subsistance adaptées à un riche environnement post-glaciaire a pu favoriser la sédentarisation de certains groupes de chasseurs-collecteurs stockeurs dès le Mésolithique moyen — bien avant donc les premiers contacts avec les populations néolithiques. L'apparition des premiers cimetières en Europe constitue un autre indice très évocateur d'une restriction de la mobilité, également perceptible à travers certains impacts anthropiques sur le milieu et divers types d'équipement (outillage lourd, vannerie, pirogues, pêcheries). / Our research leans on new analysis about the Mesolithic pits discovered during the excavation at "le Parc du Château" in Auneau (Eure-et-Loir; France). These 70 pits date between 8.000 and 5.500 cal. BC. Their various functions — i.e. graves, faunal hoards, pit-hearths, post-holes, extraction, storage, rubbish dumps — evocate long duration settlements. A European survey links to record more than 100 sites With such features, sometimes very numerous. These new data provide an original pattern, quite different from the traditional models of very mobile hunter-gatherer and short time encampment. Two kinds of features seem to be especially significant: food storage pits (similar to silos) may have allowed a delayed consumption of nuts (hazelnut or acorn) providing the bulk of food during the season of scarcity; rubbish pits indicate waste management linked to long term dwellings. From our point of view new subsistence strategies related with rich post-glacial environmental resources may allow some storing hunter-gatherer groups to adopt a sedentary way of life Since the middle Mesolithic — i.e. several millennia before the first interactions with Neolithic populations. The emergence of actual cemeteries in Euro e at the same period reveals also decreasing mobility evidence likewise some anthropogenic impacts on the environment and various equipment such as heavy lithic tools, basketry, pirogue, fishery, and so on.