Two-Component Heterojunction-based Ambipolar Field Effect Transistors for Improved Sensitivity of Ammonia Sensor

To improve the sensing response of ammonia (NH₃) sensors, a two-dimensional configuration molecule 5,11-di-naphthalen-2-yl-6,12-dihydro-indolocarbazole (ICZ-NA) was designed and synthesized as the p-channel organic semiconductor material. Bilayer organic field-effect transistor (OFET) was constructed with ICZ-NA and N,N’-bis(n-octyl)-2,6-dicyanonaphthalene-1,4,5,8-bis(dicarboximide (NDI-8CN₂) as p-type and n-type active semiconductor materials respectively, and the two-component devices exhibits excellent ambipolar FET performance. The thin film transistors based on single-component and two-component were further used as sensors for ammonia detection. Compared with the sensors based on NDI-8CN₂, the sensitivity and selectivity of ammonia detection based on two-component sensors have been greatly improved, and the ratio of current change can still be maintained over 3.65%, when the gas concentration lower to 10 ppb level. The higher sensing response and low limit of detection demonstrate that the two-component ambipolar configuration is a highly effective method for improving sensing response capability.