Photopatternable Poly(4-styrene sulfonic acid)-Wrapped MWNT Thin-Film Source/Drain Electrodes for Use in Organic Field-Effect Transistors

We describe the cross linking of poly(4-styrene-sulfonic cid) (PSS) by exposure to ultra violet (UV) light (lambda = 255 nm) under a vacuum. Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) showed that the photo-crosslinking of PSS resulted from coupling between radicals that were generated in the polymer chains by UV excitation.The photo-cross-linkable characteristics of PSS Were employed to fabricate solution-processable, Photopatternable, and conductive PSS-wrapped multiwalled carbon nanotube (MWNT) composite thin films by wrapping MWNTs with PSS in water. During photo-cross-linking, the work function of the PSS-wrapped MWNTs decreased from 4.83 to 4.53 eV following cleavage of a significant number of sulfonic acid groups. Despite the decreased work function of the PSS wrapped MWNTs the photopatterned PSS wrapped MWNTs produced good source/drain electrodes for OFETs, yeilding a mobility (0.134 +/- 0.056 cm(2)/(V s)) for the TIPS-PEN field-effect transistors fabricated using PSS-wrapped MWNTs as source/drain electrodes that was higher the mobility of gold-based transistors (0.01,1 +/- 0.004 cm(2)/(V s))