Researchers from the Department of Chemistry Barbara Panić, Hrvoj Vančik and Ivana Biljan and a student from the Department of Chemistry Lujo Matasović in collaboration with a former researcher of the Department of Chemistry Igor Rončević, currently working in the Institute of Organic Chemistry and Biochemistry in Prague, and Matej Bubaš from the Ruđer Bošković Institute have published the study Modulating electronic properties of dinitrosoarene polymers in Journal of Materials Chemistry C (IF = 7.393).
The paper was highlighted on the Front Cover of the issue, and was included in the collection of HOT papers for 2022.
In this paper, the possibility of modulating the electronic, transport, and optical properties of a conjugated organic semiconductor by using the dinitrosobenzene polymer as a model was studied. Combining computational and experimental tools the effect of solid-state packing, change in the torsional angle, surface adsorption, the conjugation in the aromatic core and substituents was investigated. Using the UV/Vis diffuse reflectance spectroscopy the band gap of 1,4-dinitrozobenzene polymer (Eg = 2.39 eV) was determined and found to be in excellent agreement with a value (Eg = 2.41 eV) calculated by GW-BSE-ZGR method. Changes occurring upon solid-state packing are separated into contributions arising from (i) the change in the torsional angle and (ii) the change in the Coulombic interaction, which strongly affects the exciton binding energies. Hybrid TD-DFT calculations showed that the effects of substituents on Eg and transport properties can be mostly attributed to changes in the torsional angle and a linear dependence between torsional angle and Eg was found. Extending the conjugation in the aromatic core leads to increased transport properties and narrowing of Eg, which could be used to identify future synthetic targets. Atomic force microscopy (AFM) was used to study morphology of thin films prepared by drop-casting a solution of 1,4-dinitrosobenzene on gold surface, while spectroscopic ellipsometry revelaed a significant narrowing of their band gap to 0.68 eV, in good agreement with TD-DFT calculations.
The research was supported in part by Croatian Science Fundation within the project From nitrogen-containing aromatic compounds to new functional organic-based materials (FunMaterials, IP-2020-02-4467).
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