Reversibility of humidity effects in pentacene based organic thin-film transistor: Experimental data and electrical modeling

Abstract

P-type organic thin-film transistors (OTFTs), in which the active semiconductor is made of pentacene with silicon dioxide as a gate insulator, were fabricated and characterized. The effects of humidity on the electrical characteristics of pentacene based thin-film transistors (pentacene-TFTs) in the linear and saturation regimes were investigated. We report the variation of the electrical parameters by relative humidity (RH) extracted from the experimental electrical characteristics current-voltage of pentacene-TFT devices. We show that the diffusion of water molecules (H 2 O), the creation of acceptor states due to the presence of oxygen and the formation of clusters in the pentacene active layer considerably affect the stability and the performances of pentacene-TFTs. The degradation of electrical parameters of the pentacene-TFTs under relative humidity (RH) can be recovered with a simple pumping under vacuum (3×10 -5 to 5×10 -5 mbar). We also show that the changes introduced by the effects of humidity are reversible. Moreover the pentacene-TFT presents an intensive response for a high relative humidity (RH=57%), which could be used for a humidity detection device technology.

Temperature dependence of the electrical properties of organic thin-film transistors based on tetraphenyldibenzoperiflanthene deposited at different substrate temperatures: Experiment and modeling

“…The interface quality of the gate insulator/organic layer plays also a critical role in the electrical performance of OTFTs. The interface trap density of the DBP-TFTs was determined by the following formula [24,41]:…”

“…8 (b), the D it values decreased with increasing of temperature for each fabricated device. For the current ratio and turn-on voltage parameters, we adapt the method used in [24] in order to determine the values of these two parameters versus temperature and for substrate temperature and they are shown in fig. 9 (a) and (b).…”

“…More recently, organic thin-film transistor based DBP (DBP-OTFTs) was fabricated in order to characterize the DBP the DBP thin-films [17]. In order to improve the performance of the OTFTs, several studies have focused on the effects induced by intrinsic factors such as humidity, illumination and temperature [16][17][18][19][20][21][22][23][24], as well as the nature of the dielectric layer and source-drain electrodes [25][26]. In order to understand the transport phenomena in the OTFTs, the behavior of the carrier mobility as function various gate voltages/carrier density and temperature has been widely studied [27][28][29][30].…”

Experimental study and analytical modeling of the channel length influence on the electrical characteristics of small-molecule thin-film transistors

“…The contact resistance provides a measure of the injection efficiency of carrier charges into the active layer of the OTFTs and characterizes the S-D electrodes/organic semiconductor interface. Several methods have been proposed to extract the contact resistance in OTFTs [16][17][18][19][20]. In our case the estimation of the contact resistance values was done using the transfer line method (TLM) [17][18].…”

“…and from the SS values we can infer the density of the interface trap in the CuPc-TFTs by using the following expression [16,23]:…”