Grain Boundary Control of Organic Semiconductors via Solvent Vapor Annealing for High-Sensitivity NO2 Detection

The microstructure of the organic semiconductor (OSC) active layer is one of the crucial topics to improve the sensing performance of gas sensors. Herein, we introduce a simple solvent vapor annealing (SVA) process to control 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) OSC films morphology and thus yields high-sensitivity nitrogen organic thin-film transistor (OTFT)-based nitrogen dioxide (NO2) sensors. Compared to pristine devices, the toluene SVA-treated devices exhibit an order of magnitude responsivity enhancement to 10 ppm NO2, further with a limit of detection of 148 ppb. Systematic studies on the microstructure of the TIPS-pentacene films reveal the large density grain boundaries formed by the SVA process, improving the capability for the adsorption of gas molecules, thus causing high-sensitivity to NO2. This simple SVA processing strategy provides an effective and reliable access for realizing high-sensitivity OTFT NO2 sensors.

Automated summary

The use of a simple SVA process successfully controlled the morphology of TIPS-pentacene OSC films, improving the sensitivity of nitrogen-based OTFT sensors. The large density grain boundaries formed by the SVA process enhanced the capability for gas molecule adsorption, resulting in high sensitivity to NO2.