Hissah Mutlaq Alqabbani

Energy Transition Specialization · Cohort 2026

Surface, Structural, Optical, and Thermal Stability Analysis in PM6 and D18-Cl Based Non-Fullerene Acceptor Organic Thin Film Blends

Organic solar cells offer distinct advantages in flexibility, lightweight design, and semi- transparency, yet poor long-term operational stability remains a barrier to commercial deployment. This project studies the structural and chemical stability of organic solar cells. State-of-the-art organic blend thin films are fabricated via spin-coating from chloroform as a solvent using polymer donors (PM6, D18-Cl) paired with non-fullerene acceptors (Y6, Y12) in an inert nitrogen environment. The project uses ultraviolet (UV), visible (Vis), and near-infrared (NIR) absorption spectroscopy to evaluate optical properties, confirming strong optical complementarity across all donor:acceptor blends. Furthermore, this project evaluates the thermal degradation of selected blend films by applying progressive thermal stress up to 300 ◦C, with each 10 minute heating step performed on a hot plate in a nitrogen environment. The absorption spectral analysis revealed optimal absorption at 140◦C for D18-Cl:Y6, and 180 ◦C for PM6:Y6; heating to 300 ◦C induced a significant breakdown in both blends. X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy were used to evaluate surface chemistry and molecular conformation. XPS confirmed the high chemical purity and stoichiometric integrity of the active layers. Raman analysis revealed that PM6 blends maintained conformational rigidity, whereas D18-Cl blends exhibited beneficial amorphous intermixing. Crucially, substituting the Y6 acceptor with Y12 preserved the donors’ primary backbone vibrations and intrinsic hole-transport networks. These findings demonstrate that targeted alkyl chain engineering mitigates morphological degradation, enhancing the operational stability and commercial viability of organic photovoltaics

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