Dependence of sensing performance of OTFT-based H2 sensor on channel length

For a hydrogen sensor based on organic thin-film transistor (OTFT) with palladium (Pd) source/drain (S/D) electrodes as the sensing medium, the effects of channel length on its sensing performance are investigated. When exposed to a fixed hydrogen concentration, the device shows lower carrier mobility for smaller channel length down to 10 mm. The involved mechanism is that for the same hydrogen-induced expansion of the S/D electrodes, the resulting compressive strain in the channel region between the S/D electrodes of the OTFT increases with decreasing channel length, leading to a larger reduction in carrier mobility and thus a higher sensitivity to hydrogen. Moreover, the response and recovery times of the sensor are hardly affected by the channel length because both are mainly governed by the diffusion of hydrogen atoms in the S/D electrodes. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The channel length has an impact on the sensing performance of the hydrogen sensor based on OTFT, with smaller channel lengths resulting in lower carrier mobility. The compressive strain in the channel region increases with decreasing channel length, leading to a larger reduction in carrier mobility and higher sensitivity to hydrogen caused by hydrogen-induced expansion of the S/D electrodes. Furthermore, the response and recovery times of the sensor are mainly controlled by the diffusion of hydrogen atoms in the S/D electrodes, and are hardly affected by the channel length.