Molecular Design and Crystal Chemistry of Polyfluorinated Naphthalene‐bis‐phenylhydrazimides with Superior Thermal and Polymorphic Stability and High Solution Processability. Issue 14 (3rd February 2023)

• Record Type: Journal Article
• Authors: Abbinante, Vincenzo Mirco; Zambra, Marco; García‐Espejo, Gonzalo; Pipitone, Candida; Giannici, Francesco; Milita, Silvia; Guagliardi, Antonietta; Masciocchi, Norberto
• Is Part Of: Chemistry. Volume 29:Issue 14(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-03
• Subjects: chemical stability -- naphtalenediimide -- polyfluorination -- thermal inertness -- X-ray diffraction; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202203441
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Naphthalene tetracarboxylic diimides (NDIs) are highly promising air‐stable n ‐type molecular semiconductor candidates for flexible and cost‐effective organic solar cells and thermoelectrics. Nonetheless, thermal and polymorphic stabilities of environmentally stable NDIs in the low‐to‐medium temperature regime (<300 °C) remain challenging properties. Structural, thermal, spectroscopic, and computational features of polyfluorinated NDI‐based molecular solids (with up to 14 F atoms per NDI molecule) are discussed upon increasing the fluorination level. Slip‐stacked arrangement of the NDI cores with suitable π–π stacking and systematically short interplanar distances (<3.2 Å) are found. All these materials exhibit superior thermal stability (up to 260 °C or above) and thermal expansion coefficients indicating a response compatible with flexible polymeric substrates. Optical bandgaps increase from 2.78 to 2.93 eV with fluorination, while LUMO energy levels decrease down to −4.37 eV, as shown per DFT calculations. The compounds exhibit excellent solubility of 30 mg mL −1 in 1, 4‐dioxane and DMF. Abstract : Polyfluorinated naphthalene‐bis‐phenylhydrazimides show high chemical and thermal inertness, possess rather low LUMO energies (down to −4.37 eV) and significantly high solubilities. All these features indicate that they are promising n‐type semiconductors for a variety of organic electronics applications.