Effect of N-Oxide Incorporation on Thiazole-Containing Conjugated Polymers

Abstract

The use of conjugated polymers (CPs) in organic electronics has been an area of continued interest over the last several years due to many advantages over their inorganic counterparts. Due to the nature of CPs, devices can be made flexible, light weight and are easy to fabricate and process in comparison to devices fabricated with inorganic materials. Due to the continued interest, developing high performance materials is essential, and therefore, developing methods for fine-tuning the optoelectronic properties of said materials becomes imperative. Tuning the electronic properties of materials allows one to mold a compound to a desired application. We introduce a new method for tuning the energy levels of thiazole containing materials through the incorporation of oxidized functional groups. Increasing the number of N-oxide moieties within the materials leads to a reduction in the HOMO-LUMO gap, due to a rise in the energy level of the HOMO as well as a lowering of the LUMO level. This phenomenon arises from a non-covalent interaction between the lone pairs of the oxygen of one thiazole- N-oxide and the σ* orbital of the S-C bond of an adjacent thiazole ring. Due to this interaction, the planarity of the system is increased, leading to a reduction in the HOMO-LUMO gap up to 0.45 eV. This effect on the planarity of the conjugated molecules can be observed through UV-Vis spectroscopy, voltammetry and computational calculations. This method establishes viable means for fine tuning thiazole-containing conjugated materials.