High Performance and Electro-Mechanical Stability in Small Molecule: Polymer Blend Flexible Organic Field-Effect Transistors

Abstract

High-performance solution processed flexible organic field-effect transistors with 6,13(bis-triisopropylsily-lethynyl) pentacene and polystyrene blend are demonstrated with high electro-mechanical stability. For −5 V operation, field-effect mobility up to 1.1 cm $^{2}~\text{V}^{\mathrm {-1}}~\text{s}^{\mathrm {-1}}$ and threshold voltage as low as −0.1 V were obtained with high current on–off ratios of $\sim 10^{5}$ due to high quality dielectric–semiconductor interface developed during solvent evaporation. Stable electrical characteristics were achieved with increasing duration of mechanical strain, and after multiple cycles of tensile and compressive strain. Drain current decay of 10%, very large trapping time of $\sim 10^{8}$ s, and a very small threshold voltage shift of 0.3 V were observed during bias stress of 1 h, signifying low charge carrier trapping and a high quality of dielectric–semiconductor interface, which was retained largely after two days of continuous tensile strain. Moreover, after 100 cycles of tensile and compressive strain, the corresponding shift in threshold voltage due to bias stress was still $\sim 0.5$ V. Overall, a high performance and stability were demonstrated under collective effects of mechanical and electrical stress.