Printed High-k Dielectric for Flexible Low-Power Extended Gate Field-Effect Transistor in Sensing Pressure

Recently, flexible organic field-effect transistor (OFET)-based pressure sensors have been attracting significant interest for promising applications in electronic skin (e-skin) and wearable healthcare monitoring systems. However, it is still challenging to achieve the low-power flexible OFET-based pressure sensors by a simple and cost-effective approach. Herein, high-k Al2O3 dielectrics on aluminum foil have been developed by a simple printing approach, and their applications in flexible low-power organic field-effect transistors (OFETs) and pressure sensor are presented. The high-k Al2O3 dielectric films prepared by our method are robust and large-area compatible, leading to a high areal capacitance and low leakage current density. Furthermore, the flexible OFET devices based on the printed Al2O3 dielectric film exhibit a field-effect mobility of 0.65 cm2/(V s), current on/off ratio up to 105, and good mechanical stability. Additionally, the OFET devices exhibit excellent uniformity, indicating the printed Al2O3 dielectric is a promising candidate to fabricate the OFETs on a large scale. The extended gate OFET-based pressure sensor achieves a high pressure sensitivity of 8 kPa–1 at an operation voltage as low as −2 V and a fast response time of <100 ms. On the merits of the high-k dielectric constant, low leakage current, and large-area compatibility, the printed Al2O3 prepared by our method will boost the development of the flexible low-power transistor-based pressure sensors for e-skin and heath monitoring applications.