Stable operation of water-gated organic field-effect transistor depending on channel flatness, electrode metals and surface treatment

Abstract

The main purpose of this study is to clarify the factors for the stable operation of a poly(3-hexylthiophene) (P3HT)-based water gated organic field effect transistor (WG-OFET). To this end, the influence of the surface morphologies and electrode metals on the transistor properties were investigated. The experimental results indicated that a flat surface improved the on/off ratio and switching repeatability. Treating the surface with a lipid membrane was found to reduce hysteresis loops in the transfer curves probably due to the reduced number of carrier traps. The Au gate electrode effectively lowered the threshold voltage. Consequently, stable transistor operation with a low threshold voltage of 35 mV was achieved by employing a gold gate electrode and lipid membrane treatment. These results suggest that WG-OFETs with an ultra-thin lipid membrane have great potential for sensor applications, and in particular for sensing water-soluble analytes.

Novel and Innovative Interface as Potential Active Layer in Chem-FET Sensor Devices for the Specific Sensing of Cs+

“…Nevertheless, prior to its implementation in a real device it is required to graft it efficiently on a suitable surface. In this context, we have recently demonstrated that SLM (Single Lipid Monolayer) [18][19][20][21] can be used as efficient organic dielectrics in Field Effect Transistors devices. Respectively we have implemented a methodology that ensures us to have SLM with unprecedented mechanical and electrical properties.…”

“…Firstly a sample of a free-OH lipid was assembled on an edge-tailored silicon prism to form a self-assembled monolayer (SAM) and then polymerized within the plane of the monolayer by applying a protocol mastered by our group to form 5. [18][19][20][21] The obtained SLM 5 was successfully characterized in situ; prior to grafting the host compound 4, using a homemade Infrared cell placed in an attenuated total reflectance mode Fourier-transform infrared (ATR-FTIR) spectrophotometer (see SI Figure S12). The initiation and propagation of the polymerization in the outer plane was initiated and ensured by the polycondensation of triethoxysilane group with the ester group on the top of the SLM 5 (Scheme 3).…”

Electrolyte-gated-organic field effect transistors functionalized by lipid monolayers with tunable pH sensitivity for sensor applications

“…[5][6][7][8][9] With respect to sensor applications in the aqueous environment, liquid electrolytes have been widely used as electrical gates in these transistors. [10][11][12][13][14][15] Then, metallic gate electrode is immersed into the electrolyte solution. Of importance is that the electrolyte-gated OFETs (EG-OFETs) effectively work at the millivolt range.…”

“…The ultrathin lipid monolayers (LMLs) with the thickness of 2.2 nm 23) were formed on the poly(3-hexylthiophene-2,5-diyl) (P3HT) films, which were employed as semiconductor channels due to its stability in the aqueous environment. 10,15) The first striking point is that the LMLs was proved to protect the transistor channels from direct exposure to the electrolyte solution. That is, LML enabled the stable transistor operation even in aqueous conditions by reducing electrochemical doping into the transistor channels.…”

Affinity driven ion exchange EG-OFET sensor for high selectivity and low limit of detection of cesium in seawater

“…This all-organic transistor consists of a 20 nm thin film of poly(3-hexylthiophene) semiconductor polymer (P3HT) and a 2.2 nm thick lipid monolayer as the gate dielectric. P3HT has a reasonable carrier mobility (10 -4 -10 -1 cm 2 V -1 s -1 ) and has the great advantage to form perfectly flat films with low roughness, hence facilitating the formation of dense and compact lipid monolayers at its interface [29]. It was also shown that the formation of the lipid monolayer on top of P3HT is not affecting strongly (same order of magnitude) its carrier mobility [30].…”