Fully Integrated Organic Field-Effect Transistor Platform to Detect and to Quantify NO2 Gas

Herein, the gas sensing characteristics of PDVT-10 organic field-effect transistor (OFET) devices are explored and integrated to build a compact analog-to-digital converter (ADC) gas detection system. The electrical characteristics of the pristine PDVT-10 OFET exhibit I-on/I-off ratio and threshold voltage as 10(4) and -12 V, respectively. Through the coating of a metal-organic framework (MOF) on the surface of PDVT-10, the I-on/I-off improves by one order of magnitude accompanied by significant positive threshold shift measured around 4 V. MOF is added as a pre-concentrating material, and the device exhibits excellent selectivity and good sensitivity toward the target NO2 gas. Most of the reports available in the literature generally focus on the gas sensing performance of individual sensors, which does not have the potential to solve real-time sensing problems. Hence, for the first time, a fully integrated ADC system is designed with just two OFETs. The integrated ADC system not only detects the NO2 gas with high sensitivity and selectivity but also generates a 5 bit digital output corresponding to different NO2 gas concentrations from 25 ppb to 1 ppm.