The Effect of Sensor Response Measurement Techniques on the Sensitivity of Organic Field‐Effect Transistors to NO ₂

Abstract Nitrogen dioxide sensors are important for environmental monitoring, and OFETs‐based devices feature high sensitivity, low production cost and power consumption. While transient pulsed saturation measurements are the most common approach to measure the sensor response, here we systematically compare it with the periodic transfer curves measurement method in both linear and saturation regimes for C8‐BTBT OFETs sensitive to NO ₂ . We show that the sensitivity strongly depends on the measurement routine, governed by competition for deep trap sites between the electrically injected holes and NO ₂ ‐induced doping. The transfer curves method reveals that mobility change dominates in the saturation regime, while threshold voltage shift dominates in the linear regime, confirming deep traps role as key sensing receptor sites. Pulsed measurements, especially in the linear regime, yielded the highest sensitivity (218 ± 18%/ppm) by combining low charge density with low duty cycle kinetics to maximize the initial deep trap availability. DFT calculations support preferential hole transfer from NO ₂ to the trap states. Altogether confirming that minimizing trap filling by injected charge (i.e., lower current density operation) enhances OFET sensitivity. This dependence on the measurement routine persists even for OFETs containing metalloporphyrin receptor layers. These findings provide guidelines for optimizing OFET sensor design and operation.