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

Abstract

We describe the cross-linking of poly(4-styrene-sulfonic acid) (PSS) by exposure to ultraviolet (UV) light (λ = 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, yielding a mobility (0.134 ± 0.056 cm²/(V s)) for the TIPS-PEN field-effect transistors fabricated using PSS-wrapped MWNTs as source/drain electrodes that was higher than the mobility of gold-based transistors (0.011 ± 0.004 cm²/(V s)).

Highly crosslinked layer-by-layer polyelectrolyte FO membranes: Understanding effects of salt concentration and deposition time on FO performance

“…This phenomenon is similar to the effect of increasing the degree of crosslinking in the previous session. The results indicate that a higher degree of PSS crosslinking is achieved with a longer UV irradiating time which is in good agreement with the literature [37]. An increase in UV irradiating time from 2 to 4 h results in a substantial decrease in reverse salt flux while only a slightly decrease is observed in water flux when using 0.5 M NaCl as a draw solution.…”

“…Moreover, the crosslinking of PSS is also proven by the decrease in the intensity of the stretching vibration peaks of the -SO 3 group as shown in Fig. 14; [37].…”

“…The existence of crosslinked PSS after UV irradiation can be proven by the decrease in the intensity of the -C-H stretching vibrations of the -CH 2 group at 2860 and 2935 cm À 1 , and the -CH associated with styrene group at 2900 cm À 1 (see Fig. 14); [37,51]. Moreover, the crosslinking of PSS is also proven by the decrease in the intensity of the stretching vibration peaks of the -SO 3 group as shown in Fig.…”

Charge Injection in Solution‐Processed Organic Field‐Effect Transistors: Physics, Models and Characterization Methods

“…In order to circumvent the solubility problems, PSS and other electrolytes have been adopted to make soluble formulations of MWCNT. Electrodes were fabricated based on PSS‐wrapped MWCNST, showing the interesting feature of being photopatternable 148. Their compatibility with solution processed TIPS‐pentacene (TIPS‐p) was demonstrated yielding high‐mobility OFETs.…”

Reversible degradation in ITO-containing organic photovoltaics under concentrated sunlight

“…Nagata et al 48 have clarified the respective effects of UV light irradiation and exposure to ozone gas on the properties of PEDOT:PSS. 48 Hong et al 50 have reported that there are two kinds of bonds in PSS that can be broken under UV exposure: the cleavage of a a-hydrogen bond generates polystyrene radicals, and the second cleavage happens between the sulfonic acid group and the phenyl group. Xing et al 49 describe a simple method to increase the conductivity of the PEDOT:PSS film by exposure to UV light in a vacuum.…”