Fabrication and Characterization of Field Effect Transistors with Phosphonic Acid Functionalized Oligothiophene Monolayers

In this project, we seek to develop substrates with oligothiophene monolayers, functionalized with phosphonic acid, in order to characterize the charge mobility of the monolayers. After the characterizations are complete, we will create field effect transistors (FETs) from the substrates to measure the hole transport properties of the film.

We develop our substrates by using the T-BAG method to deposit a thin film of the oligomer onto a SiO₂/Si plate. We then use atomic force microscopy (AFM) to characterize surface roughness and monolayer coverage. We also measure the contact angles to evaluate the surface energy of our films. 

Afterwards, we will fabricate the FET device by using thermal deposition to evaporate gold electrodes onto the substrates. We then characterize the completed FETs by measuring the current-voltage (IV) characteristics. Our primary goal is to fabricate substrates with dense monolayers of phosphonic acid functionalized oligothiophenes with suitable hole transport properties that can be used as a hole transport layer in organic photovoltaic devices.