Photolithographic Fabrication of P3HT Based Organic Thin-Film Transistors with High Mobility

Abstract

An original design and photolithographic fabrication process for Poly (3-hexylthiophene-2, 5-diyl) (P3HT) based Organic thin-film transistors (OTFTs) is presented. The structure of the transistors was based on the bottom gate bottom contact OTFT. The fabrication process was efficient, cost-effective, and relatively straightforward to implement. Most of the fabrication steps were performed at room temperature and atmospheric pressure, with the only exceptions being the high temperatures used for annealing the films and the low pressures used for depositing the metal contacts. More than 226 transistors were fabricated on a single wafer. The electrical characteristics and the geometry of the transistors were consistent across the wafer. Current–voltage (I–V) and atomic force microscopy (AFM) measurements were performed to characterize the primary electronic properties of the transistors and morphology of the P3HT, respectively. Two key performance parameters were extracted from these measurements, the threshold voltage and the field-effect mobility of the transistors. The measured mobility of these transistors was significantly higher than most results reported in the literature for other similar bottom gate bottom contact P3HT OTFTs. The higher mobility is explained primarily by the effectiveness of the fabrication process in keeping the interfacial layers free from contamination, as well as the annealing of the P3HT.

Poly(3-hexylthiophene)-Based Organic Thin-Film Transistors with Virgin Graphene Oxide as an Interfacial Layer

“…The structure of both devices was based on the BGBC OTFT structure. The details of the fabrication process are reported in our previous publication [ 32 ].…”

“…As illustrated in the figure, the P3HT was not only limited to the channel area (between the edges of the drain and the source) but has a slight overlap onto the electrodes. The devices were designed in this manner to ensure complete coverage of the channel and the Source/Drain sidewalls and create a larger contact area between the electrode and the organic semiconductor [ 32 ]. Increasing the contact area results in lower contact resistance and a higher injection rate of charge carriers into the channel, which improves device performance [ 8 , 22 ].…”

“…As illustrated in Figure 1 c, the P3HT/GO was not only limited to the channel area but has an overlap onto the electrodes. As explained for the standard devices, these devices were designed this way to increase the contact area between Au and P3HT/GO [ 32 ].…”

All Electrohydrodynamic Printed Flexible Organic Thin Film Transistors

“…Organic thin films transistors (OTFTs) provide a building block for a variety of flexible electronic devices. In OTFTs, organic semiconductors are used as the active layer, including semiconductor polymers [10,11] and small molecules; [3,12] OTFTs are superior to the conventional thin film transistors (TFTs) made from inorganic materials in terms of weight, flexibility, and cost. [13] In addition, organic materials can be processed using solution-based techniques, making the fabrication simpler and feasible at a lower temperature.…”

“…[17,25,26] Semiconductor polymers are widely used in OTFTs due to its advantages of being easy to process, low-cost, and highly flexible, but they typically exhibit lower values of charge carrier mobility. [10,27,28] Small molecular semiconductors have exhibited significantly higher field-effect mobilities compared to polymer semiconductors; however, they are difficult to process from a solution phase and easy to result in non-uniform films and dewetting phenomena. [29] Blending semiconductor polymers and small molecules is a promising strategy to further improve material processability and device performance.…”