ИСТИНА

One of perspective ways for creation of air analyzing systems is the usage of organic field effect transistors (OFETs) as sensing devices due to strong dependence of OFETs parameters on toxic gas concentration. Printing techniques allow low-cost flexible OFETs fabrication. Thus, the investigation of printed OFETs sensory properties is an actual task for today. In the present work, we investigated sensory properties of fully printed OFETs fabricated in bottom gate bottom contact geometry by inkjet printing of functional inks: silver gate, source and drain electrodes from Ag nanoparticles; dielectric layer from cross-linked poly(4-vinyl phenol); passivation layer from pentafluorothiophenol and semiconducting layer from FS-0096 inks (Flexinks Inc.). We demonstrated that such devices can be utilized as highly sensitive gas sensors for detection of extremely low concentrations of toxic gases such as ammonia. The lowest measured concentration was 100 ppb of ammonia and theoretical limit of detection was found to be 30 ppb, what is almost the same value as for the sensors based on monolayer Langmuir-Schaefer OFETs recently developed by our group[1]. However, response times of the sensors based on polymer OFETs were found to be much higher than ones of the sensors based on monolayer OFETs. Probably, the slow diffusion of ammonia molecules into thick semiconducting layer to the semiconductor-dielectric interface is the reason of such behavior. In the presentation, concentration dependence to different toxic gases as well as repeatability and reproducibility of sensor response will be presented and compared with the same data for the sensors based on monolayer OFETs. The work was performed in the framework of leading science school NSh-5698.2018.3 and supported by RFBR (project № 17-03-00222). References: [1] A.S. Sizov, A.A. Trul et al. ACS Appl Mater Interfaces, 10(50), 43831–43841(2018).