Gas Sensors Based on Organic Field-Effect Transistors: Role of Chemically Modified Dielectric Layers

Organic field-effect transistors (OFETs) were fabricated on chemically modified SiO2 dielectric layers. Changes in the mobility of the OFETs upon exposure to humidity were measured. The chemically modified dielectric layers change the OFETs' sensitivity to humidity. There is a good correlation between the sensitivity to humidity and the surface free energy of the dielectric layers. Our data suggest that surfaces with low surface free energy have low humidity adsorption probability; therefore, the corresponding OFETs also display low sensitivity to humidity. Our findings indicate that the sensitivity of OFET-based gas sensors can be tuned by using chemically modified dielectric layers.