High-Performance, Transparent Solution-Processed Organic Field-Effect Transistor with Low-k Elastomeric Gate Dielectric and Liquid Crystalline Semiconductor: Promises and Challenges

The highly flexible and stretchable polymer elastomer having a low dielectric constant (k ∼ 2.6), called poly(dimethylsiloxane) (PDMS), is a promising gate dielectric material for solution-processed organic field-effect transistors (OFETs). A detailed understanding of PDMS-based OFETs is required to extend its application to flexible electronic devices. The present work discusses about the promises and challenges of PDMS-based solution-processed OFETs using a liquid crystal (LC), 2-decyl-7-phenyl-benzothienobenzothiophene (Ph-BTBT-10), as a semiconducting channel material. The liquid crystal-OFET (LC-OFET) exhibits high electrical performance such as a high hole mobility of ∼22 cm2 V–1 s–1, a low threshold voltage (<1 V), and a high current on/off ratio of 105. The OFETs also show high optical transparency (>90%). The electrical performance of LC-OFETs is observed to have a significant correlation with the annealing temperature of the Ph-BTBT-10 layer and is also influenced by different operating conditions such as air, nitrogen, and vacuum. The OFETs demonstrate anomalous bias stress behavior and hysteresis, which are also addressed.