A Model of the V-T Characteristics for an OTFT Temperature Sensor

An analytical model, able to describe the temperature dependence of the electrical characteristics of an organic thin film transistor (OTFT), is derived from the multiple trapping and release (MTR) theory related to an exponential distribution of tail states in the organic semiconductor layer at the insulator interface. The aim is to investigate the origin of the linearity of a temperature sensor based on a diode-connected OTFT, exhibiting a linearity of 99.93% and a sensitivity of about 110 mV/K, exceeding that of silicon-based sensors, when biased with a current of 16 nA. The model shows that the linear behavior is given by the compensation of two non-linear functions of temperature, one depending on the OTFT flat-band voltage, the other, varying with the bias current, on the interface state distribution.