Enhancement of NO2 gas sensing ability through strong binding energy by modification of interface characteristics

Conjugated polymers have strong potential as sensing materials because they are flexible, simple to fabricate, and lightweight. Organic gas sensors based on field-effect transistors have attracted interest because of their high resolution through signal amplification. The main charge transport in organic transistors occurs in the vicinity of the interface between the semiconductor and the gate dielectric. Thus, controlling this interface characteristic also offers an efficient approach to enhancing the current level and sensing properties of these devices. Herein, we fabricated a sensitive NO2 sensor based on an organic transistor by introducing various self-assembled monolayers (SAMs) as a gas-interactive modifier. SiO2 surfaces were modified using four different SAMs, and the effect of the surface characteristics on the performance of the transistor-based sensors was investigated under various NO2 concentrations. Molecular dynamics simulations revealed that the SAM with N-containing functional groups strongly interacts with the target NO2 molecules, and the trend showed good agreement with NO2 sensitivity results.