Organic field effect transistors (OFET) have attracted considerable attention recently as an enabling component for “organic” or “plastic” electronics. Plastic electronics has several advantages over silicon based electronics in terms of the possibility of low cost, roll to roll processing and the development of electronics on flexible substrates. However, considerable challenges in organic semiconductors such as low mobility, irreproducible electrical characteristics and long term stability need to be overcome for OFETs to gain widespread acceptance.

In this paper, we describe results obtained using surface sensitive IR+Visible Sum Frequency Generation (SFG) non-linear optical spectroscopy on interfaces of OFETs during operation. We observe remarkable correlations between trends in the SFG spectra and electrical properties of the transistor, with varying gate voltage (VG). These results suggest that field effects on electronic conduction in thin film organic semiconductor devices are correlated to interfacial non-linear optical characteristics.