Melt-processing of complementary semiconducting polymer blends provides an average charge carrier mobility of 0.4 cm V s and current on/off ratios higher than 10 , a record performance for melt-processed organic field-effect transistors.

Charge transport in polymeric thin films is a complicated process, which involves a multitude of coupled electronic events. Because of the growing appeal of semiconducting polymers in organic electronics, it makes the fundamental understanding of charge transport increasingly important. On the other hand, it urges the solution of the processability problem, frequently associated with high-performance polymers. In this study, we introduce complementary semiconducting polymer blends (c-SPBs), aiming to provide solutions for both the fundamental understanding of charge transport and the processability problem. The c-SPBs contain a highly crystalline matrix polymer with intentionally placed conjugation-break spacers (CBSs) along the polymer backbone, thus eliminating intrachain transport, and a tie chain polymer that is a fully conjugated polymer, restoring intrachain transport by connecting π-crystalline aggregates in the matrix polymer. The results show that the addition of as little as 1 wt % tie chain polymer into the matrix polymer induces a nearly 2 order of magnitude improvement in charge carrier mobility from ∼0.015 to 1.14 cm 2 V −1 s −1 , accompanied by substantial lowering of activation energies from 100.1 to 64.6 meV. The morphological characterizations and electrical measurements confirm that tie chains are able to build the connectivity between crystalline aggregates, leading to efficient charge transport in the polymer blend films. Furthermore, this study suggests that c-SPBs can be a new platform for designing high-mobility electronic materials with enhanced solution processability for future organic electronics.

Latent H-bonds in conjugated statistical copolymers rendered semiconducting thin films resistant to solvent immersion.

Understanding high-temperature operation in organic semiconductors remains elusive. Here, we studied the effect of two alkyl side-chains, 2-octyldodecyl (C1) and 4-decyltetracecyl (C3), on the thermal stability of two types of conjugated polymer backbones: isoindigo (IID) and diketopyrolopyrrole (DPP). All polymers remain functional with high on/off ratio in ambient air at temperature up to 220 °C. However, the use of longer side-chain C3 lowers the π–π stacking distance and enables more thermally stable polymer thin film field-effect-transistors. Specifically, IID-C3 and DPP-C3 exhibited less alteration in threshold voltage as well as a reduction in effective mobility at high temperature. This behavior emphasizes the importance of close π–π stacking distance on charge transport properties of conjugated polymers and their thermal stability. This study is a starting point to deconvolute the intricate mechanism of charge transport in polymer thin films at elevated temperatures.