The investigation of the formaldehyde gas sensor based on organic thin-film-transistors

The organic thin film transistor (OTFT) with the ratio of channel width (W) to length (L) as 8000/25 was fabricated for the application of formaldehyde gas sensors. The copper phthalocyanine (CuPc) and silicon dioxide was used as the active layer and the insulating layer, respectively, and the titanium/aurum thin films were made as the source/drain electrodes for the prepared OTFT. The voltage-current characteristic curve of the OTFT was measured. The source-drain current in the saturation region changed when the prepared OTFT device was exposed to formaldehyde vapour compared to that under the circumstance of nitrogen at room temperature. It was observed that the OTFT sensor based on CuPc has high sensitivity for formaldehyde vapour. The source-drain current can be considered as a key parameter to monitor chemical species. Such OTFT devices are promising to operate as a novel chemical sensors.