Recently, Zhang Ziwei in our research group published the title of “Polyvinyl Alcohol/SiO2 Hybrid Dielectric for Transparent Flexible/Stretchable All-Carbon-Nanotube Thin-Film-Transistor Integration” on the ADVANCED ELECTRONIC MATERIALS Transistor Integration”.
In this work, we realized integratable high-performance ﬂexible and stretchable carbon nanotube transistors with PVA based gate dielectric. In this design, we adopt metallic carbon nanotube (M-CNT) and semiconducting carbon nanotube (S-CNT) networks to serve as electrodes and channels, respectively. The PVA hydrogel acts as the main body of the gate dielectric while we adopt amorphous SiO2 layer as a protection layer to be deposited on the PVA hydrogel. The thin SiO2 layer deposited by PECVD under low temperature can protect PVA hydrogel flim from being damaged during O2 plasma etching, and at the same time improve the hydrophilicity of the gate dielectric so as to improve the nanotube density.
In conclusion, with the hybrid gate dielectric, the all-carbon nanotube ﬂexible transistors possess excellent mobility over 14 cm2 V−1 s−1 under low operation voltage, on/oﬀ current ratio over 104, and subthreshold swing of 0.38 V dec−1. Besides, the ﬂexible transistor can work normally at 3 mm bending radius under a repeated in situ bending cycles for more than 2000 times. Also with the hybrid gate dielectric, the stretchable transistors are demonstrated on PDMS substrate. The stretchable transistor can be fully stretched by 50% without showing obvious damage, and the mobility is still over 10 cm2 V−1 s−1 after 1000 stretching cycles. This work shows an efficient solution to take the advantages of carbon nanotubes and PVA hydrogel for integrating high-performance ﬂexible and stretchable devices by combining low-temperature solution process with the traditional photolithography. The realized transparent ﬂexible/stretchable ACNT-TFTs are promising candidates to push the development of ﬂexible and stretchable electronics.