Solution Coating of Small Molecule/Polymer Blends Enabling Ultralow Voltage and High-Mobility Organic Transistors

Low-voltage organic field-effect transistors (OFETs) are of great interest for organic electronics applications that require low power consumption such as wearable electronics, biomedical applications, or mobile electronics. In this work, an approach leading to transistors fabricated from solution with high charge carrier mobilities operating at voltages < 1 V is presented. By blending the small-molecule semiconductor 6,13-bis(triisopropylsilyl-ethynyl)pentacene (TIPS-pentacene) with polystyrene it is possible to achieve good film coverage and uniformity as well as ultrathin semiconductor films. This reduction in thickness relative to neat films results in a high fraction of the high-mobility polymorph of TIPS-pentacene and excellent film morphologies with continuous highly crystalline domains. OFETs using SiO2 as the dielectric with average hole mobilities as high as 8.3 cm(2) V-1 s(-1) and maximum mobilities of up to 12.3 cm(2) V-1 s(-1) which favorably compares with the previous record for TIPS-pentacene, especially when considering the simplicity of the approach, are demonstrated. By depositing the optimized semiconductor blends on solution-based polymer dielectric layers of polyvinylphenol, cross-linked with 4,4-(hexafluoroisopropylidene)diphthalic anhydride, a record-high mobility of 4.2 cm(2) V-1 s(-1) for solution-processed, ultralow-voltage OFET devices (operating at <1 V) is obtained.