Solvent Vapor Assisted-Magnetic Manipulation of Molecular Orientation and Carrier Transport of the Semiconducting Polymers.

Effective control of the organic semiconductors molecular orientation and the degree of ordering is important to achieve high-performance organic electronics. Herein, we have successfully achieved the highly oriented films in the centimeter scale for a naphthalenedicarboximide-based semiconducting polymer (P(NDI2OD-T2)) by the solvent vapor annealed (SVA) of pre-cast films under high magnetic field (HMF). As revealed by the microstructural studies, the SVA-HMF films exhibit a remarkably higher degree of chain alignment and high morphological uniformity compared to the HMF-guided drop-cast films. Based on structural evolution of the films with the SVA time, a mechanism is proposed to elucidate the alignment process, which emphasizes that the chain aggregates re-formed in the swollen films trigger magnetic alignment and determine film order. Compared with the unaligned films, field-effect transistors of the magnetic aligned P(NDI2OD-T2) films have exhibited a 19-fold enhancement of electron mobility and a extraordinarily large mobility anisotropy of 125. Furthermore, significantly reduced energetic barrier for activated transport is observed on the aligned devices from temperature variable measurement. The improved performance achieved by HMF-SVA process has indicated its potential for high-performance organic electronics.