Fabrication of three-dimensional porous copper phthalocyanine films and their applications for NO2 gas sensors

In order to achieve high sensitivity in gas-sensors based on organic field-effect transistors (OFETs), the most crucial and direct approach to enhance their sensing performance and reduce response and recovery times was through appropriate modification or improvement of the organic semiconductor (OSC) layer, such as altering its surface morphology or structure. The micro/nanostructure of spin-coated copper phthalocyanine (CuPc) films was controlled by utilizing polyvinyl alcohol ordered nanofibers (PVA ONFs). The electrical and gas-sensitive properties of CuPc/PVA ONF films were investigated and analyzed. CuPc/PVA ONF film transistors exhibited improved output and transfer characteristics when the CuPc solution concentration was 75 mg mL-1, with a mobility (mu) of 6.90 x 10-4 cm2 V-1 s-1. Compared with the spin-coated CuPc film transistors, the mobility increased by 74.24%. The sensors demonstrated a relative response of 12 942% to 20 ppm NO2 gas. Additionally, they showed a response time of 1.49 min and a recovery time of 2.32 min. The response rate reached up to 90%, while the sensitivity was measured at 611%/ppm, and the limit of detection (LOD) stood at 0.2 ppm. The research presented in this article advances the potential applications of phthalocyanine materials within the realm of flexible and 3D-printed sensing technologies.