Channel length effect of P3HT:ZnO hybrid blend layer on electrical characteristics of thin-film transistors

In this present work, p-type bottom gate-bottom contact OTFTs based on semiconductor polymer poly(3-hexylthiophene) (P3HT) incorporating zinc oxide nanoparticles (ZnO) (OTFTs-P3HT:ZnO hybrid blend) with various channel lengths (L=2.5 mu m, 5 mu m, 10 mu m and 20 mu m) and constant channel width (W=10 mm) were elaborated using solution-processed P3HT:ZnO thin films, as an active layer, deposited on a Si/SiO2 substrate, without any surface treatment, by spin coating technique, and then were characterized. ZnO nanoparticles are utilized as acceptors and electron extraction materials. The effect of the channel length variation on the electrical parameters of these transistors at room atmosphere in saturation regime, has been investigated in order to better understand the dependency between the electrical performance and the channel length variation effect. As p-channel transistors, the fabricated devices exhibit a considerable variation in electrical parameters such as amount of hysteresis (Delta V-hyst), threshold voltage (V-th), density of trapped charges (N-trap), sub-threshold slope (SS), density of the interface trap (D-it), field-effect saturation mobility (mu(sat)) and current ratio (I-on/I-off) with the increase of the channel length. In this study, we report a significant improvement in the efficiency of our devices in terms of good output characteristics and good electrical parameters such as low threshold voltage, low I-off current, reduction of trap density and better field-effect saturation mobility when the channel length increases. These particularly promising results offer the possibility of using these organic thin-film transistors in several application domains such as low-cost sensing and non-volatile memory devices.