Enhancing Hole Transport\nand Autonomous Healing Properties\nof Supramolecular Columns in Unsymmetrical Discotics

Designing smart autonomous healing soft materials is\ncrucial to\nattaining cost-efficiency and optimal performance in organic semiconductors.\nIn this context, we design an unsymmetrical thiophene-fused phenazine\n(TFP)-based discotic liquid crystal (DLC) with the goal of creating\nan active organic semiconductor that encompasses favorable attributes,\nsuch as polarizability, mobility, and processability. Aligned with\nour objective, we successfully synthesized two unsymmetrical TFP core-based\nDLCs by linking alkyl chains of variable lengths at the periphery\nthrough a coupling reaction. These DLCs show room temperature columnar\noblique (Col<sub>ob</sub>) mesophase as evident from temperature-dependent\nstudies employing polarized optical microscopy (POM) and small-angle\nX-ray scattering (SAXS). We performed space charge-limited current\n(SCLC) techniques to evaluate the hole mobility of TFP-based DLCs\nand found that they have high hole mobility (∼10<sup>–3</sup> cm<sup>2</sup>/V s). Additionally, the film morphology and its self-healing\nnature have been examined using atomic force microscopy (AFM) and\nstress relaxation test. One of the unsymmetrical DLCs exhibited an\nability to relax stress over time while maintaining a constant strain\n(up to 1–3%). The rational design of these unsymmetrical discotics,\nexhibiting reduced threshold voltage (as confirmed by conductivity\nstudies) highlights their possible potential in various organic semiconductor\ndevices.