An Asymmetric Molecular Design Strategy for Organic Field-Effect Transistors with High Consistency of Performance

Organic thin-film transistors as the basic electronic element in soft electronics have drawn intensive research attention in recent years. Great achievements have been made in terms of improving the charge transport mobilities of OFET materials and devices. However, the consistency of device performance has still been an issue that impedes the industrialization of OFETs. In this paper, an asymmetric molecular design strategy was proposed for synthesizing amorphous polymer OFET materials of high mobility and fabricating OFET devices of improved reproducibility. A series of asymmetric DPP-based polymers P(DPP-CH3-TVT)x(DPP-TVT)y were designed and synthesized to demonstrate the proposed strategy. An asymmetric methyl group was introduced into the backbone of monomer TVT for creating an asymmetric steric configuration of the resulted polymers and leading lattice disorders, thus reducing the polycrystallinity of the polymers and enhancing the intra- and intermolecular charge transport. A maximum mobility of 0.64 cm2 V-1 s-1 and an average mobility of 0.39 cm2 V-1 s-1 were obtained from a nearly amorphous polymer P3 with the least crystallinity. OFET devices fabricated from this polymer achieved the best consistency of device mobility with a narrow RSD (relative standard deviation) of device mobility, which was calculated to be 21.6%. While the highly crystalline reference polymer P5 showed higher RSD of 30.8%. Our work provides insightful results which address the relationship between polymer structure, film crystallinity, lattice disorders, and the consistency of the mobility of OFET devices.