Thèse ' Development Of Lightweight Flexible Dsscs Based on Natural Dyes For Aerospatial Applications H/F - Doctorat.Gouv.Fr

Établissement : Institut National Polytechnique de Toulouse École doctorale : SDM - SCIENCES DE LA MATIERE - Toulouse Laboratoire de recherche : LCA - Laboratoire de Chimie Agro-industrielle Direction de la thèse : Jean-François FABRE ORCID 000000018158958X Début de la thèse : 2027-09-01 Date limite de candidature : 2026-11-23T23:59:59 Dye-Sensitized Solar Cells (DSSCs) offer a lightweight, flexible, and cost-effective alternative to conventional photovoltaic technologies, but their efficiency and stability under harsh conditions remain key challenges. The project aims to address these limitations by developing DSSCs based on natural pigments (bixin, phycocyanin, phycoerythrin) extracted and stabilized using deep eutectic solvents (DES), a green and innovative approach.
This PhD project leverages the complementary expertise of the LCA (France) in the chemical functionalization of natural molecules, ultrasound-assisted extraction, solvent design, DSSC formulation and the University of Tanjungpura (Indonesia) in green extraction, deep eutectic solvents, tropical biomass valorization, pigment stabilization and DSSC conception.
The project aligns with BEST's 3rd pillar by addressing sustainable transitions in energy and resources, with a specific focus on aeronautical and space applications. Expected outcomes include prototypes of flexible, UV-resistant DSSCs, as well as scientific publications and potential patents. The workflow, as detailed in the appendix will be first to optimize extraction of the dyes using DES and ultrasound to reach high extraction yield with minimum dye degradation. Bixin extracted from Annatto will be functionalized after validation of several potential electron donor groups by molecular modeling. Functionalized and natural dyes will be associated in cosensitization to cover a broad range of solar spectrum. They will be associated/complexed with metal, clays, ionic liquids , deep eutectic solvent to form an electrolyte resistant to high temperature, and UV exposure. DSSC will then be formulated with TiO2 and different supports to form a flexible DSSC without leakage. Both techno-functionality and environmental impact will be considered for DSSC final formulation. Dye-sensitized solar cells (DSSCs) are a third-generation photovoltaic technology, known for their flexibility, lightness, and lower cost compared to silicon cells. However, their efficiency and stability (sensitivity to humidity, temperature and UV radiation) limit their large-scale deployment. This project proposes a breakthrough approach by:
1. Using natural dyes (bixin from annatto, phycocyanin/phycoerythrin from algae) as sustainable, non-toxic alternatives to synthetic ones

2. Leveraging DES for:
- Green extraction of pigments (replacing toxic and/or volatile solvents such acetone, hexane...).
- Stabilization of pigments
- Electrolyte formulation in DSSCs (Adhitya et al., 2023).
3. Optimizing DSSCs for extreme conditions:
- Thermal stability (>80°C for aeronautics).
- UV/radiation resistance (for space applications).
- Mechanical flexibility (integration on curved surfaces).
Innovation:
- First integration of multiple natural pigments (bixin+phycobiliprotein) + DES + DSSCs for aeronautical/space applications.
- Circular economy: Valorization of agricultural by-products (annatto seeds, algae) and DES recyclability.
This project proposes to combine :
1. LCA's expertise in biomass functionalization
2. Tanjungpura University's expertise in natural dyes, green extraction with DES.
3. Tests under simulated real-world conditions (temperature cycles, UV light)
The main objectives of this thesis are:

Developing DSSCs with stabilized natural pigments :
Extraction of phycocyanin/phycoerythrin (algae) and bixin (annatto) by DES (deep eutectic solvents) and ultrasonication (Fabre et al., 2024; Jubaidah et al., 2026; Rahmalia et al., 2024)

Functionalization of bixin with donor groups to improve electron transport (Agócs et al., 2017).

Stabilization: Use Metal complexes (Rahmalia et al., 2022, 2021) DES and/or activated clays to protect pigments from UV degradation and thermal stress (Rahmalia et al., 2021, 2020, 2018).

Co-sensitization : Combination of two or more dyes to get panchromatic DSSCs (Cole et al., 2019; Islam et al., 2018).

Optimizing DSSCs for the aerospace industry (Harris et al., 2002; Iswarya et al., 2025; Safyanu et al., 2019)
Flexibility and lightness : Integration on flexible substrates (e.g., polymer films, textiles) (Gong et al., 2012; Santos et al., 2025)
Thermic resistance (Adjali et al., 2022; Silva et al., 2005; Xue et al., 2012)
UV resistance and low pressure (Kabir et al., 2022)
Energy efficiency : Target a yield > 1% via co- sensitization (e.g. bixin and phycoerythrin).

Sustainability
Life Cycle Assessment (LCA): Compare environmental impact of DES vs. organic solvents (e.g., acetone, acetonitrile) for a same extraction efficiency.
Compare optimized DSSC with classical silicon-based solar cells for a same conversion efficiency.
The methodology will be structured around 4 axes :
1. Extraction and purification of pigments :
Algae (phycocyanin/phycoerythrin): Collaboration with algae farms (Indonesia) and/or specialized French laboratories
Annatto ( bixin ): Use of agricultural by-products (Indonesia)
Methods : DES (deep eutectic solvents) vs. classical methods (ethanol, hexane) with the help of ultrasonication
2. Characterization : Chromatography (GC and HPLC), Spectrometry (UV-Vis, NMR, FT-IR, Raman), Physical characterization (Rheology, Mechanical tests, Thermic behavior (DSC, TGA))
3. Functionalization of pigments :
In silico analysis (DFT in particular) of functionalized pigments
Grafting of selected donor groups via click-Chemistry (reactions without toxic solvents).
Stabilization : Formulation with metals, DES, and activated clays to stabilize the pigment and the electrolyte.
4. Formulation and DSSCs :
Deposition of pigments on TiO and flexible supports
Electrolytes : I/I solubilized in bio-based DES and/or Dielectric solvents
Measurement of Conversion Efficiency (through measurement of Voc, Isc) and electronic behaviour (through Electrochemical Impedance Spectroscopy)
5. Testing (Conversion efficiency, )
Aeronautics :
Conception of systems Captors-DSSC suitable for aeronautic applications (Sundriyal and Bhattacharya, 2019)
Space :
Trials of collaboration with the MELiSSA project (ESA) for life support systems.

The candidate will have:
- Education : Master 2 in Materials, Organic Chemistry or Process Engineering .
- Technical skills :
o Experience in organic/inorganic synthesis.
o Proficiency in characterization techniques (UV-Vis, FT-IR, NMR).
o Knowledge of electrochemistry ( cyclic voltammetry )
- Cross-cutting skills :
o English : Level B2
o Autonomy and team spirit
o Mobility : Availability for stays abroad (up to 1 year).
Additional advantages :
- Experience in green chemistry (DES, bio-based solvents)
- Experience in molecular modeling (DFT, COSMO)
- Experience in life cycle assessment
- Experience in the valorization of agricultural by-products.

Application link: https://edd-projets.utoulouse.fr/

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