Thèse Générateurs Thermoélectriques à Haute Performance Totalement Imprimés et Fabriqués sur des Substrats Souples H/F

Université Paris Cité

Établissement : Université Paris Cité
École doctorale : Chimie Physique & Chimie Analytique de Paris-Centre
Laboratoire de recherche : Interfaces, Traitements, Organisation et Dynamique des Systèmes
Direction de la thèse : GIORGIO MATTANA ORCID 0000000305523970
Début de la thèse : 2026-10-01
Date limite de candidature : 2026-05-11T23:59:59

L'objectif de cette thèse est le développement de générateurs thermoélectriques (TEG) entièrement imprimés, organiques et hybrides (organique/inorganique), fabriqués sur des substrats flexibles. La première partie de la thèse consistera à développer des encres semiconductrices à base de matériaux hybrides innovants (également en collaboration avec Sorbonne Université (Paris) et l'INRS (Canada)), nécessaires à la fabrication de TEG imprimés. Un procédé de fabrication de tels TEG entièrement imprimés sur films flexibles, déjà disponible au sein de l'équipe, sera utilisé afin de miniaturiser les TEG. Une attention particulière sera portée à la réduction des dimensions afin de maintenir des performances compatibles avec les exigences des applications visées. Les TEG seront testés en termes de stabilité en conditions ambiantes et de résistance aux contraintes mécaniques. L'objectif final de la thèse est d'obtenir des TEG entièrement imprimés, flexibles et à haut rendement de conversion de puissance, adaptés aux applications en électronique portable.

The problems of environmental degradation are pushing researchers towards the quest for efficient and environmentally friendly energy sources or conversion technologies. In this respect, thermoelectric materials (TEMs), i.e. materials capable of converting heat into electrical energy, have attracted considerable attention in the last twenty years, for a wide range of applications.[1] For instance, it has been recently demonstrated that the temperature difference between the surface of human skin and the environment can be successfully exploited by TEMs to power low-energy consumption wearable electronics, provided that their performances are carefully optimised.[2] TEMs are used for the fabrication of devices called thermoelectric generators (TEGs) which, in their simplest form, consist of a thin TEM layer sandwiched between two electrodes. Among the different types of materials currently employed for the fabrication of TEGs, organic and hybrid inorganic/organic semiconductors have aroused significant interest in the last ten years.[3,4,5] However, significant challenges remain to develop fully operational and marketable TEGs based on organic and hybrid semiconductors such as: i) relatively low energy conversion efficiency;[3] fabrication and scalability issues, that severely impact their commercial viability.[5]
At the moment, there is a strong need for the development of new high energy conversion efficiency organic and hybrid TEMs and TEGs using fabrication protocols and techniques able to improve the devices scalability and thus promote the technological transfer to the industrial sector for commercial production.
At the ITODYS laboratory, thanks to a PhD thesis that ended in October 2025, we have already defined a fabrication protocol[7] enabling us to produce all-printed TEGs on flexible foils. The current devices, exhibiting a relatively large surface area (~ 6 cm2), show performances slightly better than the current state of the art (maximum output power of 2 nW/generator for T = 40 K, ambient stability over 75 days). While encouraging, these results still require profound work in terms of size reduction and performances improvement to match the requirements imposed by the targeted final applications (powering electronic devices and systems used in the field of wearable electronics) and to ensure the technological transfer to the industry.

The main objectives of this thesis project may be summarised as follows:
(1) formulation of two new different classes of printable semiconducting inks for the fabrication of TEGs, namely:
- purely organic inks, mostly based on poly(benzodifurandione) (air stable n-type doped) and on polythiophenes (p-type doped);
- hybrid organic/inorganic materials, belonging to two different families: (i) inorganic metal coordination complexes connected by organic units (developed in collaboration with researchers at Sorbonne Université). Preliminary tests on thin films made of these materials have already shown promising results in terms of very high Seebeck coefficient values; (ii) graphene derivatives (such as rGO)/organic polymer matrices (based on polyaniline or polythiophenes) composite materials;
(2) adaptation of the already existing process-flow to produce such all-printed devices on plastic foils to obtain TEGs with a smaller active area (~ 1 cm2);
(3) physico-chemical characterisation of the printed layers and devices (transport phenomena and magnetoresistive properties will be analysed in collaboration with researchers at Institut National de la Recherche Scientifique in Canada) as well as full thermoelectric characterisation of the printed TEGs;
(4) ageing in ambient conditions and mechanical characterisation of the printed generators to test their stability when subjected to mechanical stresses, will be also performed.

Méthode (stratégies envisagées pour atteindre les objectifs).
1st year: formulation of printable, functional inks: the PhD candidate will focus on the synthesis, formulation and deposition by printing techniques of semiconducting inks, both organic (including air-stable and water-soluble polymers) and hybrid. Morphological and chemical characterisation of the printed layers will be performed to check the quality of the materials deposited. The synthesis of the inorganic coordination complexes will be performed in Sorbonne Université laboratories.
2nd year: fabrication and characterisation of all-printed TEGs on flexible substrates: the PhD candidate will i) design a planar structure for the fabrication of the TEGs. Ideally, this structure should be no larger than 1 cm2 (using high-resolution printing techniques such as high-precision capillary printing, available in the hosting team ) to be easily integrated into wearable electronic systems; ii) fabricate the whole structure of the TEGs (by exclusive means of printing techniques); iii) perform the fully thermoelectric characterisation of the devices (I/V and V/T curves, output power measurements). Based on the results of these characterisations, optimisation steps of the functional inks formulation will be carried out. The characterisation of the printed layers in terms of electronic transport will be done in collaboration with Prof. Orgiu's team. PhD student exchange as well as sample shipment are envisaged.
3rd year: tests on ambient stability and mechanical characterisation: the PhD student will: i) evaluate the ambient stability of the all-printed devices (accelerated life tests will be performed in a climatic chamber); ii) evaluate the thermoelectric performances of the printed devices under bending. During this last year, the student will also focus on the papers and thesis writing; he/she will also participate in at least one international conference.