High field-effect mobility in oriented thin films of D-A type semiconducting polymers by engineering stable interfacial system

[Display omitted] •A stable interfacial system is developed to fabricate oriented floating films.•UFTM is used to fabricate large-area oriented thin films.•Viscosity plays a dominant role to govern the extent and direction of orientation.•The stable interfacial system helps in a higher degree of aggregation.•A very high field-effect mobility of 12.4 cm2V−1s−1 is achieved in DPPT-TT. Conjugated polymers (CPs) have emerged as excellent organic semiconducting materials for flexible electronic applications. CPs exhibit a notably fast carrier transport along their main π-conjugated backbone followed by inter-chain hopping compelling the need to form large and ordered domains in thin films. Therefore, the formation of larger domains, along with their orientation, is critical in controlling the electrical properties of CP-based organic electronic devices. However, controlling the molecular ordering along with the formation of large aggregates is a challenge. In this work, the unidirectional floating film transfer method (UFTM) has been utilized to prepare oriented thin films of CPs, which is a highly facile, cost-effective and material utilization efficient technique. We have demonstrated that extent and direction of molecular orientation in the fabricated thin films can be tuned along with the higher degree of aggregation. The rheological aspects, especially viscosity, play a significant role in determining molecular ordering along with the formation of these large aggregates. Active control of viscosity to achieve a stable interfacial viscous system is paramount to achieving this, resulting in a very high mobility of 12.4 cm2V−1s−1.