Chalcogen-Substituted Fluorinated π-Conjugated Systems: DFT-Guided Insights Into Optoelectronic Properties,...

Area of Science:

• Materials Science
• Organic Electronics
• Computational Chemistry

Background:

• Fluorine incorporation significantly alters molecular electronic properties due to its strong electron-withdrawing nature.
• Low-bandgap π-conjugated systems are crucial for efficient organic solar cells (OSCs).

Purpose of the Study:

• To investigate the impact of fluorine and chalcogen variation (O, S, Se) on the optoelectronic properties of benzodifurandione-oxindole based π-conjugated systems.
• To explore the potential of these fluorinated materials in high-performance OSCs and understand the underlying structure-property relationships.

Main Methods:

• Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations were employed for electronic structure analysis.
• Hirshfeld surface analysis, Reduced Density Gradient (RDG), and Quantum Theory of Atoms in Molecules (QTAIM) were used to characterize non-covalent interactions (NCIs).
• Electron Localization Function (ELF) and Localized Orbital Locator (LOL) analyses were performed to understand electronic distribution and bonding.

Main Results:

• A progressive redshift in absorption and photoluminescence spectra was observed from O to Se, indicating enhanced π-conjugation and reduced HOMO-LUMO gaps.
• The selenium-containing derivative (M3, X=Se) showed the most redshifted optical properties, suitable for near-infrared (NIR) applications.
• Bulk heterojunction (BHJ) devices achieved power conversion efficiencies (PCEs) up to 7.00%.

Conclusions:

• Fluorinated low-bandgap materials with chalcogen variation offer tunable optoelectronic properties.
• The study provides fundamental insights into molecular design for next-generation fluorinated materials for high-efficiency OSCs.
• Understanding non-covalent interactions is key to optimizing molecular packing and stability for device performance.