|
Organic thin film transistors (OTFTs) have been studied with many interests, due to their key advantage of relatively simple and low temperature processing, low cost and mechanical flexibility. Several different organic semiconductors have been investigated for application of TFTs. Among the various organic semiconductors, pentacene-based TFTs show the best results in terms of the electrical performance. But there is significant manufacturing problem which is not clear whether their cost is sufficiently low for future applications, such as those in flexible displays, RFID tags or other disposable devices. Inkjet printing technique can remove this problem. Source/drain (S/D) electrodes using inkjet printing method is demonstrated. The proposed S/D fabrication method is very promising compared to other methods, such as lithography, thermal evaporation, spin coating and dipping coating. It has the advantages of being fast and simple with high throughput. In this reason, We have fabricated pentacene TFTs in which the conventional gate, S/D metal electrodes are replaced by organic material, Poly (3, 4-ethylenedioxythiophene)-Polystyrene Sulfonate (PEDOT:PSS) by inkjet printing method. PEDOT:PSS is most widely used as an electrode material of semiconductors among other polymer materials. However, PEDOT:PSS in solution form has a low conductivity, hence becomes unsuitable for electrode fabrication. To improve its conductive property, 5 % dimethyl sulfoxide (DMSO) was mixed with the PEDOT:PSS solution. A surfactant, triton X-100, which lowers surface tension and facilitates spreading between surface and PEDOT:PSS was also added. And we used plastic film substrate, and compared conventional Si wafer substrate. The physical and electrical properties of the polymer gate insulator are measured by atomic force microscope (AFM) and I-V measurement. In this work, we fabricated all organic TFTs with PEDOT:PSS S/D electrode and plastic film substrate. And electrical properties are compared with conventional pentacene-based organic TFTs with inorganic electrodes and/or Si wafer substrate |