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 semiconducting channel material. The liquid crystal-OFET (LC-OFET) exhibits high electrical performance such as high hole mobility of ~ 22 cm2V-1s-1, low threshold voltage (< 1 V) and high current on/ off ratio of 105. The OFETs also show high optical transparency (> 90 %). The electrical performance of LC-OFETs are observed to have a significant correlation with the annealing temperature of Ph-BTBT-10 layer and is also influenced by the different operating conditions such as air, nitrogen and vacuum. The OFETs demonstrate anomalous bias stress behavior and hysteresis which are also addressed.